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Energy Focus, Inc./DE – ‘10-K’ for 12/31/20 – ‘EX-101.LAB’

On:  Thursday, 3/25/21, at 8:04am ET   ·   For:  12/31/20   ·   Accession #:  924168-21-14   ·   File #:  1-36583

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  As Of               Filer                 Filing    For·On·As Docs:Size

 3/25/21  Energy Focus, Inc./DE             10-K       12/31/20  102:9.9M

Annual Report   —   Form 10-K
Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-K        Annual Report                                       HTML   1.19M 
 2: EX-4.4      Instrument Defining the Rights of Security Holders  HTML     34K 
 3: EX-21.1     Subsidiaries List                                   HTML     25K 
 4: EX-23.1     Consent of Expert or Counsel                        HTML     25K 
 5: EX-31.1     Certification -- §302 - SOA'02                      HTML     31K 
 6: EX-31.2     Certification -- §302 - SOA'02                      HTML     30K 
 7: EX-32.1     Certification -- §906 - SOA'02                      HTML     28K 
14: R1          Cover Page                                          HTML     92K 
15: R2          Consolidated Balance Sheets                         HTML    142K 
16: R3          Consolidated Balance Sheets (Parenthetical)         HTML     47K 
17: R4          Consolidated Statements of Operations               HTML     90K 
18: R5          Consolidated Statements of Comprehensive Loss       HTML     42K 
19: R6          Consolidated Statements of Stockholders' Equity     HTML     95K 
20: R7          Consolidated Statements of Cash Flows               HTML    135K 
21: R8          Nature of Operations                                HTML     37K 
22: R9          Summary of Significant Accounting Policies          HTML     94K 
23: R10         Restructuring                                       HTML     56K 
24: R11         Leases                                              HTML    150K 
25: R12         Inventories                                         HTML     43K 
26: R13         Property and Equipment                              HTML     43K 
27: R14         Prepaid Expenses and Other Current Assets           HTML     36K 
28: R15         Accrued Liabilities                                 HTML     37K 
29: R16         Debt                                                HTML     44K 
30: R17         Commitments and Contingencies                       HTML     28K 
31: R18         Stockholders' Equity                                HTML    126K 
32: R19         Income Taxes                                        HTML     60K 
33: R20         Product and Geographic Information                  HTML     45K 
34: R21         Related Party Transactions                          HTML     33K 
35: R22         Legal Matters                                       HTML     29K 
36: R23         Subsequent Events                                   HTML     29K 
37: R24         Supplementary Financial Information to Item 8.      HTML     69K 
38: R25         Schedule II - Schedule of Valuation and Qualifying  HTML     50K 
                Accounts                                                         
39: R26         Summary of Significant Accounting Policies Summary  HTML    120K 
                of Significant Accounting (Policies)                             
40: R27         Summary of Significant Accounting Policies Summary  HTML     53K 
                of Significant Accounting Policies (Tables)                      
41: R28         Restructuring Restructuring (Tables)                HTML     41K 
42: R29         Leases (Tables)                                     HTML    108K 
43: R30         Inventories Inventories (Tables)                    HTML     43K 
44: R31         Property and Equipment Property and Equipment       HTML     42K 
                (Tables)                                                         
45: R32         Prepaid Expenses and Other Current Assets Prepaid   HTML     37K 
                Expenses and Other Current Assets (Tables)                       
46: R33         Accrued Liabilities Accrued Liabilities (Tables)    HTML     36K 
47: R34         Stockholders' Equity Stockholders' Equity (Tables)  HTML    109K 
48: R35         Income Taxes Income Taxes (Tables)                  HTML     59K 
49: R36         Product and Geographic Information (Tables)         HTML     43K 
50: R37         Supplementary Financial Information to Item 8.      HTML     66K 
                (Tables)                                                         
51: R38         Nature of Operations - Narrative (Details)          HTML     30K 
52: R39         Summary of Significant Accounting Policies - Cash   HTML     32K 
                and Cash Equivalents (Details)                                   
53: R40         Summary of Significant Accounting Policies -        HTML     29K 
                Inventories (Details)                                            
54: R41         Summary of Significant Accounting Policies -        HTML     27K 
                Accounts Receivable (Details)                                    
55: R42         Summary of Significant Accounting Policies -        HTML     37K 
                Income Taxes (Details)                                           
56: R43         Summary of Significant Accounting Policies -        HTML     66K 
                Financial Instruments (Details)                                  
57: R44         Summary of Significant Accounting Policies -        HTML     38K 
                Rollforward (Details)                                            
58: R45         Summary of Significant Accounting Policies -        HTML     31K 
                Long-lived Assets (Details)                                      
59: R46         Summary of Significant Accounting Policies -        HTML     53K 
                Concentration Risk (Details)                                     
60: R47         Summary of Significant Accounting Policies -        HTML     39K 
                Reconciliation of Basic and Diluted Income (Loss)                
                per Share (Details)                                              
61: R48         Summary of Significant Accounting Policies - Net    HTML     36K 
                Loss Per Share (Details)                                         
62: R49         Summary of Significant Accounting Policies -        HTML     27K 
                Advertising Expenses (Details)                                   
63: R50         Summary of Significant Accounting Policies -        HTML     41K 
                Product Warranties (Details)                                     
64: R51         Summary of Significant Accounting Policies -        HTML     35K 
                Schedule of Warranty Activity (Details)                          
65: R52         Summary of Significant Accounting Policies - New    HTML     38K 
                Accounting Pronouncements (Details)                              
66: R53         Restructuring - Narrative (Details)                 HTML     63K 
67: R54         Restructuring - Reconciliation of Restructuring     HTML     44K 
                Liability (Details)                                              
68: R55         Leases - Narrative (Details)                        HTML     46K 
69: R56         Leases - Components of Lease Cost (Details)         HTML     42K 
70: R57         Leases - Schedule of Supplemental Balance Sheet     HTML     44K 
                Information (Details)                                            
71: R58         Leases - Schedule of Future Maturities of Lease     HTML     99K 
                Liabilities (Details)                                            
72: R59         Leases - Schedule of Supplemental Cash Flow         HTML     32K 
                Information (Details)                                            
73: R60         Inventories - Schedule of Inventory (Details)       HTML     38K 
74: R61         Inventories - Reserve Rollforward (Details)         HTML     33K 
75: R62         Property and Equipment (Details)                    HTML     70K 
76: R63         Prepaid Expenses and Other Current Assets           HTML     42K 
                (Details)                                                        
77: R64         Accrued Liabilities (Details)                       HTML     44K 
78: R65         Debt - Credit Facilities (Details)                  HTML     94K 
79: R66         Debt - Convertible Notes (Details)                  HTML     65K 
80: R67         Debt - Iliad Note (Details)                         HTML     64K 
81: R68         Debt - PPP Loan (Details)                           HTML     36K 
82: R69         Commitments and Contingencies - Narrative           HTML     31K 
                (Details)                                                        
83: R70         Stockholders' Equity - Narrative (Details)          HTML    119K 
84: R71         Stockholders' Equity - Impact of Results for        HTML     35K 
                Stock-Based Compensation (Details)                               
85: R72         Stockholders' Equity - Estimates Utilized           HTML     40K 
                (Details)                                                        
86: R73         Stockholders' Equity - Summary of Option Activity   HTML     62K 
                (Details)                                                        
87: R74         Stockholders' Equity - Options Outstanding and      HTML     79K 
                Exercisable (Details)                                            
88: R75         Stockholders' Equity - Summary of Restricted Stock  HTML     51K 
                Activity (Details)                                               
89: R76         Income Taxes - Narrative (Details)                  HTML     44K 
90: R77         Income Taxes - Components (Details)                 HTML     36K 
91: R78         Income Taxes - Reconciliation (Details)             HTML     38K 
92: R79         Income Taxes - Temporary Differences (Details)      HTML     41K 
93: R80         Product and Geographic Information (Details)        HTML     47K 
94: R81         Related Party Transactions (Details)                HTML     51K 
95: R82         Subsequent Events (Details)                         HTML     29K 
96: R83         Supplementary Financial Information to Item 8.      HTML     70K 
                (Details)                                                        
97: R84         Schedule II - Schedule of Valuation and Qualifying  HTML     41K 
                Accounts (Details)                                               
98: R9999       Uncategorized Items - efoi-20201231.htm             HTML     35K 
100: XML         IDEA XML File -- Filing Summary                      XML    182K  
13: XML         XBRL Instance -- efoi-20201231_htm                   XML   2.22M 
99: EXCEL       IDEA Workbook of Financial Reports                  XLSX    133K 
 9: EX-101.CAL  XBRL Calculations -- efoi-20201231_cal               XML    313K 
10: EX-101.DEF  XBRL Definitions -- efoi-20201231_def                XML    764K 
11: EX-101.LAB  XBRL Labels -- efoi-20201231_lab                     XML   2.05M 
12: EX-101.PRE  XBRL Presentations -- efoi-20201231_pre              XML   1.23M 
 8: EX-101.SCH  XBRL Schema -- efoi-20201231                         XSD    211K 
101: JSON        XBRL Instance as JSON Data -- MetaLinks              461±   686K  
102: ZIP         XBRL Zipped Folder -- 0000924168-21-000014-xbrl      Zip    410K

‘EX-101.LAB’   —   XBRL Labels — efoi-20201231_lab

This Exhibit is an XBRL XML File.

                                                                                                                                                                                
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<link:label id="lab_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitments and Contingencies Disclosure [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureTextBlock"/>
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<link:label id="lab_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_ceac62e3-cbdb-4aeb-bc0f-5ac0bbcd5de9_terseLabel_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party [Axis] </link:label>
<link:label id="lab_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_label_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="lab_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AmortizationOfDebtDiscountPremium_339937d3-5d21-454d-987e-8042aab955bf_terseLabel_en-US" xlink:label="lab_us-gaap_AmortizationOfDebtDiscountPremium" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amortization of loan discounts and origination fees </link:label>
<link:label id="lab_us-gaap_AmortizationOfDebtDiscountPremium_label_en-US" xlink:label="lab_us-gaap_AmortizationOfDebtDiscountPremium" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amortization of Debt Discount (Premium) </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfDebtDiscountPremium" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfDebtDiscountPremium"/>
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<link:label id="lab_us-gaap_PayablesAndAccrualsAbstract_ad4dac1d-1146-43be-af93-6d54f8e03558_terseLabel_en-US" xlink:label="lab_us-gaap_PayablesAndAccrualsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payables and Accruals [Abstract] </link:label>
<link:label id="lab_us-gaap_PayablesAndAccrualsAbstract_label_en-US" xlink:label="lab_us-gaap_PayablesAndAccrualsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payables and Accruals [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PayablesAndAccrualsAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PayablesAndAccrualsAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PayablesAndAccrualsAbstract" xlink:to="lab_us-gaap_PayablesAndAccrualsAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ValuationAllowancesAndReservesDomain_65c49bdd-70fc-4cad-a08f-e60a4dc990f3_terseLabel_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] </link:label>
<link:label id="lab_us-gaap_ValuationAllowancesAndReservesDomain_label_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain" xlink:to="lab_us-gaap_ValuationAllowancesAndReservesDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_46d1a90f-4a15-4821-a8f1-20bda7002762_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vested (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ProceedsFromIssuanceOfCommonStockAndWarrants_0eaf205c-2789-491b-83d5-699bc2dc7897_terseLabel_en-US" xlink:label="lab_efoi_ProceedsFromIssuanceOfCommonStockAndWarrants" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from the issuance of common stock and warrants </link:label>
<link:label id="lab_efoi_ProceedsFromIssuanceOfCommonStockAndWarrants_label_en-US" xlink:label="lab_efoi_ProceedsFromIssuanceOfCommonStockAndWarrants" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Issuance of Common Stock and Warrants </link:label>
<link:label id="lab_efoi_ProceedsFromIssuanceOfCommonStockAndWarrants_documentation_en-US" xlink:label="lab_efoi_ProceedsFromIssuanceOfCommonStockAndWarrants" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Issuance of Common Stock and Warrants </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ProceedsFromIssuanceOfCommonStockAndWarrants" xlink:href="efoi-20201231.xsd#efoi_ProceedsFromIssuanceOfCommonStockAndWarrants"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ProceedsFromIssuanceOfCommonStockAndWarrants" xlink:to="lab_efoi_ProceedsFromIssuanceOfCommonStockAndWarrants" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_e6856493-5e35-4ca9-97d3-13613485c82c_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Restructuring and Related Costs [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Restructuring and Related Costs [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:to="lab_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_InventoryWriteDown_d33a3c18-19da-41a0-8f23-910ea52214f6_terseLabel_en-US" xlink:label="lab_us-gaap_InventoryWriteDown" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Provision for slow-moving and obsolete inventories </link:label>
<link:label id="lab_us-gaap_InventoryWriteDown_label_en-US" xlink:label="lab_us-gaap_InventoryWriteDown" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Write-down </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryWriteDown" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryWriteDown"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InventoryWriteDown" xlink:to="lab_us-gaap_InventoryWriteDown" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredOperatingLeaseLiabilityCurrent_21dbc7e5-c113-44d1-8e5e-1553507db3bf_terseLabel_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured lease liabilities </link:label>
<link:label id="lab_efoi_RestructuredOperatingLeaseLiabilityCurrent_label_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Operating Lease, Liability, Current </link:label>
<link:label id="lab_efoi_RestructuredOperatingLeaseLiabilityCurrent_documentation_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Operating Lease, Liability, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredOperatingLeaseLiabilityCurrent" xlink:href="efoi-20201231.xsd#efoi_RestructuredOperatingLeaseLiabilityCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredOperatingLeaseLiabilityCurrent" xlink:to="lab_efoi_RestructuredOperatingLeaseLiabilityCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredFinanceCostsGross_68c76c0b-5f9a-4c98-a4c2-149bf46e7769_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredFinanceCostsGross" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt issuance costs </link:label>
<link:label id="lab_us-gaap_DeferredFinanceCostsGross_label_en-US" xlink:label="lab_us-gaap_DeferredFinanceCostsGross" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Issuance Costs, Gross </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsGross" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredFinanceCostsGross"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredFinanceCostsGross" xlink:to="lab_us-gaap_DeferredFinanceCostsGross" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_NetProceedsFromTheConversionOfConvertibleDebtToPreferredStock_f4561e0d-616f-4d26-bb5d-d6cc83882365_terseLabel_en-US" xlink:label="lab_efoi_NetProceedsFromTheConversionOfConvertibleDebtToPreferredStock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net proceeds from the conversion of convertible debt to preferred stock </link:label>
<link:label id="lab_efoi_NetProceedsFromTheConversionOfConvertibleDebtToPreferredStock_label_en-US" xlink:label="lab_efoi_NetProceedsFromTheConversionOfConvertibleDebtToPreferredStock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net proceeds from the conversion of convertible debt to preferred stock </link:label>
<link:label id="lab_efoi_NetProceedsFromTheConversionOfConvertibleDebtToPreferredStock_documentation_en-US" xlink:label="lab_efoi_NetProceedsFromTheConversionOfConvertibleDebtToPreferredStock" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net proceeds from the conversion of convertible debt to preferred stock </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_NetProceedsFromTheConversionOfConvertibleDebtToPreferredStock" xlink:href="efoi-20201231.xsd#efoi_NetProceedsFromTheConversionOfConvertibleDebtToPreferredStock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_NetProceedsFromTheConversionOfConvertibleDebtToPreferredStock" xlink:to="lab_efoi_NetProceedsFromTheConversionOfConvertibleDebtToPreferredStock" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeaseOperatingLeaseCostNetOfSubleaseIncome_468aa7ce-6f3c-44b5-964b-fcbaf89748a1_totalLabel_en-US" xlink:label="lab_efoi_RestructuredLeaseOperatingLeaseCostNetOfSubleaseIncome" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured lease cost, net </link:label>
<link:label id="lab_efoi_RestructuredLeaseOperatingLeaseCostNetOfSubleaseIncome_label_en-US" xlink:label="lab_efoi_RestructuredLeaseOperatingLeaseCostNetOfSubleaseIncome" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Lease, Operating Lease, Cost, Net Of Sublease Income </link:label>
<link:label id="lab_efoi_RestructuredLeaseOperatingLeaseCostNetOfSubleaseIncome_documentation_en-US" xlink:label="lab_efoi_RestructuredLeaseOperatingLeaseCostNetOfSubleaseIncome" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Lease, Operating Lease, Cost, Net Of Sublease Income </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeaseOperatingLeaseCostNetOfSubleaseIncome" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeaseOperatingLeaseCostNetOfSubleaseIncome"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeaseOperatingLeaseCostNetOfSubleaseIncome" xlink:to="lab_efoi_RestructuredLeaseOperatingLeaseCostNetOfSubleaseIncome" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProceedsFromWarrantExercises_6713fa27-ae52-4897-9e65-9821bfd10dc7_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromWarrantExercises" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from the exercise of warrants </link:label>
<link:label id="lab_us-gaap_ProceedsFromWarrantExercises_label_en-US" xlink:label="lab_us-gaap_ProceedsFromWarrantExercises" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Warrant Exercises </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromWarrantExercises" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromWarrantExercises"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromWarrantExercises" xlink:to="lab_us-gaap_ProceedsFromWarrantExercises" xlink:type="arc" order="1"/>
<link:label id="lab_srt_RangeMember_28d69432-13e7-41b6-a0f6-b1acc7e2d7a6_terseLabel_en-US" xlink:label="lab_srt_RangeMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statistical Measurement [Domain] </link:label>
<link:label id="lab_srt_RangeMember_label_en-US" xlink:label="lab_srt_RangeMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statistical Measurement [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_RangeMember" xlink:to="lab_srt_RangeMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_738da63c-9c74-4348-b3f7-9b23fae15c0f_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award [Line Items] </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringCostAndReserveLineItems_df20d9ec-9119-4ca2-b271-49e857162f8c_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringCostAndReserveLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Cost and Reserve [Line Items] </link:label>
<link:label id="lab_us-gaap_RestructuringCostAndReserveLineItems_label_en-US" xlink:label="lab_us-gaap_RestructuringCostAndReserveLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Cost and Reserve [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems" xlink:to="lab_us-gaap_RestructuringCostAndReserveLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DomesticSupplierMember_310ef741-38df-442a-9dbc-861e12eb8aa6_terseLabel_en-US" xlink:label="lab_efoi_DomesticSupplierMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Domestic Supplier </link:label>
<link:label id="lab_efoi_DomesticSupplierMember_label_en-US" xlink:label="lab_efoi_DomesticSupplierMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Domestic Supplier [Member] </link:label>
<link:label id="lab_efoi_DomesticSupplierMember_documentation_en-US" xlink:label="lab_efoi_DomesticSupplierMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Domestic Supplier </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DomesticSupplierMember" xlink:href="efoi-20201231.xsd#efoi_DomesticSupplierMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DomesticSupplierMember" xlink:to="lab_efoi_DomesticSupplierMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOfDebt_045887a6-73e8-4864-a027-72fe71c99f71_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfDebt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from issuance </link:label>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOfDebt_label_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfDebt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Issuance of Debt </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfDebt" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfDebt"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromIssuanceOfDebt" xlink:to="lab_us-gaap_ProceedsFromIssuanceOfDebt" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PreferredStockMember_080ec835-3c60-49af-b273-de9d7ea176ee_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred Stock </link:label>
<link:label id="lab_us-gaap_PreferredStockMember_label_en-US" xlink:label="lab_us-gaap_PreferredStockMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred Stock [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredStockMember" xlink:to="lab_us-gaap_PreferredStockMember" xlink:type="arc" order="1"/>
<link:label id="lab_dei_SecurityExchangeName_ef02561b-c1ab-4e27-a7a4-2ba3824bad34_terseLabel_en-US" xlink:label="lab_dei_SecurityExchangeName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Security Exchange Name </link:label>
<link:label id="lab_dei_SecurityExchangeName_label_en-US" xlink:label="lab_dei_SecurityExchangeName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Security Exchange Name </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_SecurityExchangeName"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_SecurityExchangeName" xlink:to="lab_dei_SecurityExchangeName" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities_70992c75-8909-49a6-aa7b-d11e4362a682_totalLabel_en-US" xlink:label="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total adjustments </link:label>
<link:label id="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities_label_en-US" xlink:label="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProceedsFromConvertibleDebt_e2e9826a-0102-4525-bca2-2ca10d366de6_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromConvertibleDebt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from convertible notes </link:label>
<link:label id="lab_us-gaap_ProceedsFromConvertibleDebt_label_en-US" xlink:label="lab_us-gaap_ProceedsFromConvertibleDebt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Convertible Debt </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromConvertibleDebt" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromConvertibleDebt"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromConvertibleDebt" xlink:to="lab_us-gaap_ProceedsFromConvertibleDebt" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StandardProductWarrantyAccrualCurrent_13d5780b-f078-4000-87ba-b5eb056cb3ce_terseLabel_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyAccrualCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued warranty reserve </link:label>
<link:label id="lab_us-gaap_StandardProductWarrantyAccrualCurrent_de7fae29-29b8-4774-903b-c526d8ab4256_periodStartLabel_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyAccrualCurrent" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balance at the beginning of the year </link:label>
<link:label id="lab_us-gaap_StandardProductWarrantyAccrualCurrent_79c1addd-4100-4083-9ccc-3fbc734985d0_periodEndLabel_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyAccrualCurrent" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued warranty expense </link:label>
<link:label id="lab_us-gaap_StandardProductWarrantyAccrualCurrent_label_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyAccrualCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Standard Product Warranty Accrual, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrualCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StandardProductWarrantyAccrualCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StandardProductWarrantyAccrualCurrent" xlink:to="lab_us-gaap_StandardProductWarrantyAccrualCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_3a2f8f32-5baa-4fb4-88a6-2c572b336a17_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance lease right-of-use asset </link:label>
<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-of-Use Asset, before Accumulated Amortization </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization" xlink:to="lab_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingIncomeLoss_844427cf-409a-4538-ad78-f3d129b13afc_totalLabel_en-US" xlink:label="lab_us-gaap_OperatingIncomeLoss" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss from operations </link:label>
<link:label id="lab_us-gaap_OperatingIncomeLoss_label_en-US" xlink:label="lab_us-gaap_OperatingIncomeLoss" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Income (Loss) </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingIncomeLoss" xlink:to="lab_us-gaap_OperatingIncomeLoss" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredRevenueCurrent_d6c70214-21ae-4e9e-badf-81d116c26b3b_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredRevenueCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred revenue </link:label>
<link:label id="lab_us-gaap_DeferredRevenueCurrent_label_en-US" xlink:label="lab_us-gaap_DeferredRevenueCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Revenue, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredRevenueCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredRevenueCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredRevenueCurrent" xlink:to="lab_us-gaap_DeferredRevenueCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredOperatingLeaseLiabilityNoncurrent_c350f793-6a24-4839-b85b-f42d622df580_terseLabel_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured lease liabilities, net of current portion </link:label>
<link:label id="lab_efoi_RestructuredOperatingLeaseLiabilityNoncurrent_label_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Operating Lease, Liability, Noncurrent </link:label>
<link:label id="lab_efoi_RestructuredOperatingLeaseLiabilityNoncurrent_documentation_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Operating Lease, Liability, Noncurrent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredOperatingLeaseLiabilityNoncurrent" xlink:href="efoi-20201231.xsd#efoi_RestructuredOperatingLeaseLiabilityNoncurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredOperatingLeaseLiabilityNoncurrent" xlink:to="lab_efoi_RestructuredOperatingLeaseLiabilityNoncurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_afe11a10-d384-4adb-9aca-8f807f0c3228_terseLabel_en-US" xlink:label="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Exercise Price (in dollars per share) </link:label>
<link:label id="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_label_en-US" xlink:label="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Exercise Price </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:to="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncreaseDecreaseInDepositOtherAssets_5cbb1944-c5d0-4d5b-8d9e-6ccd4ecf1591_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInDepositOtherAssets" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Short-term deposits </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInDepositOtherAssets_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInDepositOtherAssets" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Deposit Assets </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDepositOtherAssets" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInDepositOtherAssets"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInDepositOtherAssets" xlink:to="lab_us-gaap_IncreaseDecreaseInDepositOtherAssets" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LiabilitiesCurrent_64b22fb8-3cfd-4845-98cd-f2c609481bf1_totalLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total current liabilities </link:label>
<link:label id="lab_us-gaap_LiabilitiesCurrent_label_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesCurrent" xlink:to="lab_us-gaap_LiabilitiesCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_TradeAndOtherAccountsReceivablePolicy_bbeb1295-60eb-4ba4-8d9f-da3229af5a2f_terseLabel_en-US" xlink:label="lab_us-gaap_TradeAndOtherAccountsReceivablePolicy" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts receivables </link:label>
<link:label id="lab_us-gaap_TradeAndOtherAccountsReceivablePolicy_label_en-US" xlink:label="lab_us-gaap_TradeAndOtherAccountsReceivablePolicy" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeAndOtherAccountsReceivablePolicy" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TradeAndOtherAccountsReceivablePolicy"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TradeAndOtherAccountsReceivablePolicy" xlink:to="lab_us-gaap_TradeAndOtherAccountsReceivablePolicy" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_IncreaseDecreaseInInventoryLevelsGross_95340c2a-68c5-414b-b2ec-43696cc15987_terseLabel_en-US" xlink:label="lab_efoi_IncreaseDecreaseInInventoryLevelsGross" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reduction of gross inventory levels </link:label>
<link:label id="lab_efoi_IncreaseDecreaseInInventoryLevelsGross_label_en-US" xlink:label="lab_efoi_IncreaseDecreaseInInventoryLevelsGross" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) In Inventory Levels, Gross </link:label>
<link:label id="lab_efoi_IncreaseDecreaseInInventoryLevelsGross_documentation_en-US" xlink:label="lab_efoi_IncreaseDecreaseInInventoryLevelsGross" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) In Inventory Levels, Gross </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_IncreaseDecreaseInInventoryLevelsGross" xlink:href="efoi-20201231.xsd#efoi_IncreaseDecreaseInInventoryLevelsGross"/>
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<link:label id="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_c05e7959-1916-42c2-931b-3d7d9a3a6a87_terseLabel_en-US" xlink:label="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid and other current assets </link:label>
<link:label id="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_519f08d0-818e-416d-8285-eaed9bf359b1_totalLabel_en-US" xlink:label="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total prepaid and other current assets </link:label>
<link:label id="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_label_en-US" xlink:label="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid Expense and Other Assets, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_08b79354-f8f6-476f-889c-eb698c94fe91_periodStartLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Outstanding at beginning of period (in dollars per share) </link:label>
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<link:label id="lab_us-gaap_VariableRateDomain_8dec5c8b-529f-4239-8018-3e92c403ccc2_terseLabel_en-US" xlink:label="lab_us-gaap_VariableRateDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Variable Rate [Domain] </link:label>
<link:label id="lab_us-gaap_VariableRateDomain_label_en-US" xlink:label="lab_us-gaap_VariableRateDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Variable Rate [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableRateDomain" xlink:to="lab_us-gaap_VariableRateDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccruedProfessionalFeesCurrent_39fcaaa5-c49d-4fdc-9bf9-0908d5fc00f5_terseLabel_en-US" xlink:label="lab_us-gaap_AccruedProfessionalFeesCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued legal and professional fees </link:label>
<link:label id="lab_us-gaap_AccruedProfessionalFeesCurrent_label_en-US" xlink:label="lab_us-gaap_AccruedProfessionalFeesCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued Professional Fees, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedProfessionalFeesCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedProfessionalFeesCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccruedProfessionalFeesCurrent" xlink:to="lab_us-gaap_AccruedProfessionalFeesCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_VariableRateAxis_cc9809bf-5b94-40e1-b996-5384c2792227_terseLabel_en-US" xlink:label="lab_us-gaap_VariableRateAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Variable Rate [Axis] </link:label>
<link:label id="lab_us-gaap_VariableRateAxis_label_en-US" xlink:label="lab_us-gaap_VariableRateAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Variable Rate [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableRateAxis" xlink:to="lab_us-gaap_VariableRateAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_5cdd1b06-903f-48ed-b34f-5ff532ada6b6_terseLabel_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Valuation allowance </link:label>
<link:label id="lab_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_label_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance"/>
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<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue_5842ccad-a33d-41fd-85bf-43a2d3bef41f_totalLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total future undiscounted lease payments </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Payment, Due </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue"/>
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<link:label id="lab_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_85171f0b-4773-412a-8aae-0b45034f91d6_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock withheld in lieu of income tax withholding from share-based compensation </link:label>
<link:label id="lab_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_label_en-US" xlink:label="lab_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Decrease for Tax Withholding Obligation </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
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<link:label id="lab_us-gaap_AssetsAbstract_1cbf17e0-6231-4ca1-a866-64923ac8bd23_terseLabel_en-US" xlink:label="lab_us-gaap_AssetsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> ASSETS </link:label>
<link:label id="lab_us-gaap_AssetsAbstract_label_en-US" xlink:label="lab_us-gaap_AssetsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="lab_us-gaap_AssetsAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_db866849-042b-4e05-92d3-5f4543a06eba_terseLabel_en-US" xlink:label="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investment, Name [Axis] </link:label>
<link:label id="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_label_en-US" xlink:label="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investment, Name [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
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<link:label id="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_0d5f7c65-3e01-407c-970e-bd19de06c03a_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_d27688c5-b878-4faf-8ddd-9afb9cc2d0f0_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vesting period </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period </link:label>
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<link:label id="lab_us-gaap_AccountingPoliciesAbstract_576cf166-6237-4b63-87c7-5cba2507aef5_terseLabel_en-US" xlink:label="lab_us-gaap_AccountingPoliciesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Policies [Abstract] </link:label>
<link:label id="lab_us-gaap_AccountingPoliciesAbstract_label_en-US" xlink:label="lab_us-gaap_AccountingPoliciesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Policies [Abstract] </link:label>
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<link:label id="lab_us-gaap_FurnitureAndFixturesMember_d53b02d6-a2e1-4fd0-8109-0d69a778de7b_terseLabel_en-US" xlink:label="lab_us-gaap_FurnitureAndFixturesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Furniture and fixtures </link:label>
<link:label id="lab_us-gaap_FurnitureAndFixturesMember_label_en-US" xlink:label="lab_us-gaap_FurnitureAndFixturesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Furniture and Fixtures [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FurnitureAndFixturesMember"/>
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<link:label id="lab_dei_EntityAddressStateOrProvince_4e0a5a40-1d84-435f-8100-12838b1b4ef3_terseLabel_en-US" xlink:label="lab_dei_EntityAddressStateOrProvince" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, State or Province </link:label>
<link:label id="lab_dei_EntityAddressStateOrProvince_label_en-US" xlink:label="lab_dei_EntityAddressStateOrProvince" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, State or Province </link:label>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_25d79a47-f5d8-497d-a27d-0dcbc2485761_negatedLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vested (in shares) </link:label>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_583cbc41-913b-401c-9a25-0e908c8f7e3b_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise price (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Exercise Price </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingLeasePayments_fbe7f67d-12b7-4517-8e00-fc2e5601301d_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasePayments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating cash flows from operating leases </link:label>
<link:label id="lab_us-gaap_OperatingLeasePayments_label_en-US" xlink:label="lab_us-gaap_OperatingLeasePayments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Payments </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeasePayments"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasePayments" xlink:to="lab_us-gaap_OperatingLeasePayments" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeaseOperatingLeaseCost_2ca07ef1-c31b-42c3-8e38-d6fdff83fee1_terseLabel_en-US" xlink:label="lab_efoi_RestructuredLeaseOperatingLeaseCost" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease cost </link:label>
<link:label id="lab_efoi_RestructuredLeaseOperatingLeaseCost_label_en-US" xlink:label="lab_efoi_RestructuredLeaseOperatingLeaseCost" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Lease, Operating Lease, Cost </link:label>
<link:label id="lab_efoi_RestructuredLeaseOperatingLeaseCost_documentation_en-US" xlink:label="lab_efoi_RestructuredLeaseOperatingLeaseCost" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Lease, Operating Lease, Cost </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeaseOperatingLeaseCost" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeaseOperatingLeaseCost"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeaseOperatingLeaseCost" xlink:to="lab_efoi_RestructuredLeaseOperatingLeaseCost" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccountsPayableCurrent_3957b45a-c19b-4481-a73b-6ece49ec3e39_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsPayableCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts payable </link:label>
<link:label id="lab_us-gaap_AccountsPayableCurrent_label_en-US" xlink:label="lab_us-gaap_AccountsPayableCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Payable, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsPayableCurrent" xlink:to="lab_us-gaap_AccountsPayableCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAndExercisableTableTextBlock_7c87bf86-cbb7-4777-8f33-eb40ee43dd4f_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAndExercisableTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Options Outstanding </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAndExercisableTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAndExercisableTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding and Exercisable [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAndExercisableTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAndExercisableTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAndExercisableTableTextBlock" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAndExercisableTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityAvailableAmountBasedOnQualifiedAccounts_f556ce80-e286-4b7b-8459-6f4098dcabe8_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAvailableAmountBasedOnQualifiedAccounts" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amount available based on qualifying accounts </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAvailableAmountBasedOnQualifiedAccounts_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAvailableAmountBasedOnQualifiedAccounts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Available Amount Based On Qualified Accounts </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAvailableAmountBasedOnQualifiedAccounts_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAvailableAmountBasedOnQualifiedAccounts" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Available Amount Based On Qualified Accounts </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityAvailableAmountBasedOnQualifiedAccounts" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityAvailableAmountBasedOnQualifiedAccounts"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityAvailableAmountBasedOnQualifiedAccounts" xlink:to="lab_efoi_LineOfCreditFacilityAvailableAmountBasedOnQualifiedAccounts" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SubleaseIncome_8ed251b5-bff6-4494-9504-8e16c3152f86_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_SubleaseIncome" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Sublease income </link:label>
<link:label id="lab_us-gaap_SubleaseIncome_label_en-US" xlink:label="lab_us-gaap_SubleaseIncome" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Sublease Income </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubleaseIncome" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubleaseIncome"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubleaseIncome" xlink:to="lab_us-gaap_SubleaseIncome" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsExercisableAbstract_5fbf86d4-a4d3-422a-8c02-6d985991a7ef_terseLabel_en-US" xlink:label="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsExercisableAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> OPTIONS EXERCISABLE </link:label>
<link:label id="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsExercisableAbstract_label_en-US" xlink:label="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsExercisableAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Options Exercisable [Abstract] </link:label>
<link:label id="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsExercisableAbstract_documentation_en-US" xlink:label="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsExercisableAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Options Exercisable [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsExercisableAbstract" xlink:href="efoi-20201231.xsd#efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsExercisableAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsExercisableAbstract" xlink:to="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsExercisableAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RetainedEarningsAccumulatedDeficit_ac83eed7-5c72-4d43-a960-eddd4044ffe4_terseLabel_en-US" xlink:label="lab_us-gaap_RetainedEarningsAccumulatedDeficit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated deficit </link:label>
<link:label id="lab_us-gaap_RetainedEarningsAccumulatedDeficit_label_en-US" xlink:label="lab_us-gaap_RetainedEarningsAccumulatedDeficit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retained Earnings (Accumulated Deficit) </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RetainedEarningsAccumulatedDeficit" xlink:to="lab_us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingLeaseRightOfUseAsset_8fb8ebb9-e992-4529-83e9-4cdb2f6fca5b_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease, right-of-use asset </link:label>
<link:label id="lab_us-gaap_OperatingLeaseRightOfUseAsset_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Right-of-Use Asset </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseRightOfUseAsset" xlink:to="lab_us-gaap_OperatingLeaseRightOfUseAsset" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccruedSalesCommissionCurrent_e1385a2d-b64e-42d1-bbf4-6d29453609f7_terseLabel_en-US" xlink:label="lab_us-gaap_AccruedSalesCommissionCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued sales commissions </link:label>
<link:label id="lab_us-gaap_AccruedSalesCommissionCurrent_label_en-US" xlink:label="lab_us-gaap_AccruedSalesCommissionCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued Sales Commission, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedSalesCommissionCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedSalesCommissionCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccruedSalesCommissionCurrent" xlink:to="lab_us-gaap_AccruedSalesCommissionCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_GainsLossesOnExtinguishmentOfDebt_575d5032-1a98-4fe6-aa85-38153ab6a1b4_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss on extinguishment of debt </link:label>
<link:label id="lab_us-gaap_GainsLossesOnExtinguishmentOfDebt_label_en-US" xlink:label="lab_us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gain (Loss) on Extinguishment of Debt </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:to="lab_us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList_485aa5e7-6e50-4648-b925-e7564dac5e64_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List] </link:label>
<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList" xlink:to="lab_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityMonthlyFacilityFeePercent_973f8307-1643-47b6-8eaa-e715c0bf3983_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityMonthlyFacilityFeePercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Monthly service fee </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityMonthlyFacilityFeePercent_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityMonthlyFacilityFeePercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Monthly Facility Fee, Percent </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityMonthlyFacilityFeePercent_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityMonthlyFacilityFeePercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Monthly Facility Fee, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityMonthlyFacilityFeePercent" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityMonthlyFacilityFeePercent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityMonthlyFacilityFeePercent" xlink:to="lab_efoi_LineOfCreditFacilityMonthlyFacilityFeePercent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncomeTaxesPaid_54ee6821-2142-40b5-8289-509294326356_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxesPaid" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash paid in year for income taxes </link:label>
<link:label id="lab_us-gaap_IncomeTaxesPaid_label_en-US" xlink:label="lab_us-gaap_IncomeTaxesPaid" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Taxes Paid </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaid" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxesPaid"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxesPaid" xlink:to="lab_us-gaap_IncomeTaxesPaid" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_acf77222-a166-4ec5-b31e-946c5e79d6ef_periodStartLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Outstanding at beginning of period (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_83441384-7ddf-4364-85e8-4eda95e6e368_periodEndLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Outstanding at end of period (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_CommunalMember_d878992b-234e-4e88-a585-54c7a240c7bc_terseLabel_en-US" xlink:label="lab_efoi_CommunalMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Communal </link:label>
<link:label id="lab_efoi_CommunalMember_label_en-US" xlink:label="lab_efoi_CommunalMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Communal [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_CommunalMember" xlink:href="efoi-20201231.xsd#efoi_CommunalMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_CommunalMember" xlink:to="lab_efoi_CommunalMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_5e5f6c67-bf33-40e7-9661-20ef8d4fcf4d_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unamortized stock compensation expense </link:label>
<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_label_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:to="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LegalMattersAndContingenciesTextBlock_c48595e1-bd1d-42bc-92ef-2e1f8265f2d0_terseLabel_en-US" xlink:label="lab_us-gaap_LegalMattersAndContingenciesTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Legal Matters </link:label>
<link:label id="lab_us-gaap_LegalMattersAndContingenciesTextBlock_label_en-US" xlink:label="lab_us-gaap_LegalMattersAndContingenciesTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Legal Matters and Contingencies [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LegalMattersAndContingenciesTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LegalMattersAndContingenciesTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LegalMattersAndContingenciesTextBlock" xlink:to="lab_us-gaap_LegalMattersAndContingenciesTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_09e4351f-8cd7-4245-9574-50c3e103d5d6_terseLabel_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> New Accounting Pronouncements or Change in Accounting Principle [Line Items] </link:label>
<link:label id="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_label_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> New Accounting Pronouncements or Change in Accounting Principle [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_srt_MajorCustomersAxis_9b3c9a17-464c-4dba-beaa-d07ce3fc90e4_terseLabel_en-US" xlink:label="lab_srt_MajorCustomersAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer [Axis] </link:label>
<link:label id="lab_srt_MajorCustomersAxis_label_en-US" xlink:label="lab_srt_MajorCustomersAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MajorCustomersAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_MajorCustomersAxis" xlink:to="lab_srt_MajorCustomersAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_344826d5-5a02-481d-9a5c-d9028f7d91f2_terseLabel_en-US" xlink:label="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> State </link:label>
<link:label id="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current State and Local Tax Expense (Benefit) </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:to="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SharesOutstanding_05992dfc-c047-40d0-948e-bd5c5890d52f_periodStartLabel_en-US" xlink:label="lab_us-gaap_SharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Beginning balance (in shares) </link:label>
<link:label id="lab_us-gaap_SharesOutstanding_deac6bcd-6c8a-40b4-824b-dcffad1c35a9_periodEndLabel_en-US" xlink:label="lab_us-gaap_SharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ending balance (in shares) </link:label>
<link:label id="lab_us-gaap_SharesOutstanding_label_en-US" xlink:label="lab_us-gaap_SharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Shares, Outstanding </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesOutstanding"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharesOutstanding" xlink:to="lab_us-gaap_SharesOutstanding" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PreferredStockValue_e96ee5f8-9029-44d4-8c07-4c83897019f7_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred stock, par value $0.0001 per share: Authorized: 2,000,000 shares in 2019 and 2018 Issued and outstanding: no shares in 2016 and 2015 </link:label>
<link:label id="lab_us-gaap_PreferredStockValue_label_en-US" xlink:label="lab_us-gaap_PreferredStockValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred Stock, Value, Issued </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockValue"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredStockValue" xlink:to="lab_us-gaap_PreferredStockValue" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_b036b842-9ad0-43df-bdd3-88ffe8564253_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Range of Exercise Prices, lower limit (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:to="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_PaymentsForPlacementAgentCommissions_12698f93-3648-47f7-a05b-1eebec9825bb_terseLabel_en-US" xlink:label="lab_efoi_PaymentsForPlacementAgentCommissions" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amount paid for placement agent commissions </link:label>
<link:label id="lab_efoi_PaymentsForPlacementAgentCommissions_label_en-US" xlink:label="lab_efoi_PaymentsForPlacementAgentCommissions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments For Placement Agent Commissions </link:label>
<link:label id="lab_efoi_PaymentsForPlacementAgentCommissions_documentation_en-US" xlink:label="lab_efoi_PaymentsForPlacementAgentCommissions" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments For Placement Agent Commissions </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_PaymentsForPlacementAgentCommissions" xlink:href="efoi-20201231.xsd#efoi_PaymentsForPlacementAgentCommissions"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_PaymentsForPlacementAgentCommissions" xlink:to="lab_efoi_PaymentsForPlacementAgentCommissions" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncomeTaxPolicyTextBlock_16e9af75-e884-4b4a-b7e8-46becbaec5d0_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income taxes </link:label>
<link:label id="lab_us-gaap_IncomeTaxPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_IncomeTaxPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax, Policy [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPolicyTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxPolicyTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxPolicyTextBlock" xlink:to="lab_us-gaap_IncomeTaxPolicyTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LeaseCost_4925b2ff-5182-4fd3-a859-2438bdc87694_totalLabel_en-US" xlink:label="lab_us-gaap_LeaseCost" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total lease cost, net </link:label>
<link:label id="lab_us-gaap_LeaseCost_label_en-US" xlink:label="lab_us-gaap_LeaseCost" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease, Cost </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCost" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseCost"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeaseCost" xlink:to="lab_us-gaap_LeaseCost" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingExpenses_e17939af-14bc-4313-9754-a922aee37f0a_totalLabel_en-US" xlink:label="lab_us-gaap_OperatingExpenses" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total operating expenses </link:label>
<link:label id="lab_us-gaap_OperatingExpenses_label_en-US" xlink:label="lab_us-gaap_OperatingExpenses" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Expenses </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingExpenses"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingExpenses" xlink:to="lab_us-gaap_OperatingExpenses" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_b8d44b90-71cf-4c6e-957b-247032d67eef_verboseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercisable (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CommonStockParOrStatedValuePerShare_81b03e1e-4f4c-40fe-b642-cd195904e1af_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockParOrStatedValuePerShare" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock, par value (in dollars per share) </link:label>
<link:label id="lab_us-gaap_CommonStockParOrStatedValuePerShare_label_en-US" xlink:label="lab_us-gaap_CommonStockParOrStatedValuePerShare" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Par or Stated Value Per Share </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockParOrStatedValuePerShare" xlink:to="lab_us-gaap_CommonStockParOrStatedValuePerShare" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PaymentsOfDebtExtinguishmentCosts_a00b5c7a-5c8c-4723-842c-ba3f12da656b_terseLabel_en-US" xlink:label="lab_us-gaap_PaymentsOfDebtExtinguishmentCosts" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payment amount </link:label>
<link:label id="lab_us-gaap_PaymentsOfDebtExtinguishmentCosts_label_en-US" xlink:label="lab_us-gaap_PaymentsOfDebtExtinguishmentCosts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payment for Debt Extinguishment or Debt Prepayment Cost </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts" xlink:to="lab_us-gaap_PaymentsOfDebtExtinguishmentCosts" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree_6e76f0e5-be6d-4160-80fa-e39f0bff46f1_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2023 </link:label>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Three </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PaymentsOfFinancingCosts_c5dd22d6-39b9-461a-aa99-59f8a38c1d6e_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_PaymentsOfFinancingCosts" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments for deferred financing costs & termination fees </link:label>
<link:label id="lab_us-gaap_PaymentsOfFinancingCosts_label_en-US" xlink:label="lab_us-gaap_PaymentsOfFinancingCosts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments of Financing Costs </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfFinancingCosts"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsOfFinancingCosts" xlink:to="lab_us-gaap_PaymentsOfFinancingCosts" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OtherLiabilitiesNoncurrent_9e2ee229-0a7b-4d06-a614-614012dee7ef_terseLabel_en-US" xlink:label="lab_us-gaap_OtherLiabilitiesNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other liabilities </link:label>
<link:label id="lab_us-gaap_OtherLiabilitiesNoncurrent_label_en-US" xlink:label="lab_us-gaap_OtherLiabilitiesNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Liabilities, Noncurrent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrent" xlink:to="lab_us-gaap_OtherLiabilitiesNoncurrent" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ExercisePriceRangeOneMember_b9baf267-6c0c-4096-8d9d-703d8e75e392_terseLabel_en-US" xlink:label="lab_efoi_ExercisePriceRangeOneMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise price, range one </link:label>
<link:label id="lab_efoi_ExercisePriceRangeOneMember_label_en-US" xlink:label="lab_efoi_ExercisePriceRangeOneMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise Price Range One [Member] </link:label>
<link:label id="lab_efoi_ExercisePriceRangeOneMember_documentation_en-US" xlink:label="lab_efoi_ExercisePriceRangeOneMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> The first exercise price range. </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ExercisePriceRangeOneMember" xlink:href="efoi-20201231.xsd#efoi_ExercisePriceRangeOneMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ExercisePriceRangeOneMember" xlink:to="lab_efoi_ExercisePriceRangeOneMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_InventoryValuationReservesWriteOffs_12788645-8f91-444d-b707-8bfe9e9abff7_terseLabel_en-US" xlink:label="lab_efoi_InventoryValuationReservesWriteOffs" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Write-off for disposed inventory </link:label>
<link:label id="lab_efoi_InventoryValuationReservesWriteOffs_label_en-US" xlink:label="lab_efoi_InventoryValuationReservesWriteOffs" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Valuation Reserves, Write-Offs </link:label>
<link:label id="lab_efoi_InventoryValuationReservesWriteOffs_documentation_en-US" xlink:label="lab_efoi_InventoryValuationReservesWriteOffs" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Valuation Reserves, Write-Offs </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_InventoryValuationReservesWriteOffs" xlink:href="efoi-20201231.xsd#efoi_InventoryValuationReservesWriteOffs"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_InventoryValuationReservesWriteOffs" xlink:to="lab_efoi_InventoryValuationReservesWriteOffs" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StandardProductWarrantyAccrualPreexistingIncreaseDecrease_8d75bba9-65c2-49ef-8178-adb3e76c0179_terseLabel_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyAccrualPreexistingIncreaseDecrease" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustments to existing warranties </link:label>
<link:label id="lab_us-gaap_StandardProductWarrantyAccrualPreexistingIncreaseDecrease_label_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyAccrualPreexistingIncreaseDecrease" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Standard Product Warranty Accrual, Increase (Decrease) for Preexisting Warranties </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrualPreexistingIncreaseDecrease" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StandardProductWarrantyAccrualPreexistingIncreaseDecrease"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StandardProductWarrantyAccrualPreexistingIncreaseDecrease" xlink:to="lab_us-gaap_StandardProductWarrantyAccrualPreexistingIncreaseDecrease" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DeferredTaxAssetsOperatingLossCarryforwardsPortionAvailableAfterApplicationOfIRCSection382Limitations_d17b7b5c-cfde-40b5-be37-6a652a50e9a5_terseLabel_en-US" xlink:label="lab_efoi_DeferredTaxAssetsOperatingLossCarryforwardsPortionAvailableAfterApplicationOfIRCSection382Limitations" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred tax assets, operating loss carryforwards, portion available after application of IRC Section 382 limitations </link:label>
<link:label id="lab_efoi_DeferredTaxAssetsOperatingLossCarryforwardsPortionAvailableAfterApplicationOfIRCSection382Limitations_label_en-US" xlink:label="lab_efoi_DeferredTaxAssetsOperatingLossCarryforwardsPortionAvailableAfterApplicationOfIRCSection382Limitations" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Operating Loss Carryforwards, Portion Available After Application Of IRC Section 382 Limitations </link:label>
<link:label id="lab_efoi_DeferredTaxAssetsOperatingLossCarryforwardsPortionAvailableAfterApplicationOfIRCSection382Limitations_documentation_en-US" xlink:label="lab_efoi_DeferredTaxAssetsOperatingLossCarryforwardsPortionAvailableAfterApplicationOfIRCSection382Limitations" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Operating Loss Carryforwards, Portion Available After Application Of IRC Section 382 Limitations </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DeferredTaxAssetsOperatingLossCarryforwardsPortionAvailableAfterApplicationOfIRCSection382Limitations" xlink:href="efoi-20201231.xsd#efoi_DeferredTaxAssetsOperatingLossCarryforwardsPortionAvailableAfterApplicationOfIRCSection382Limitations"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DeferredTaxAssetsOperatingLossCarryforwardsPortionAvailableAfterApplicationOfIRCSection382Limitations" xlink:to="lab_efoi_DeferredTaxAssetsOperatingLossCarryforwardsPortionAvailableAfterApplicationOfIRCSection382Limitations" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_InventoryValuationReservesProvisionAccrual_ccb531d6-ac42-4286-962e-9692345143ee_terseLabel_en-US" xlink:label="lab_efoi_InventoryValuationReservesProvisionAccrual" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrual </link:label>
<link:label id="lab_efoi_InventoryValuationReservesProvisionAccrual_label_en-US" xlink:label="lab_efoi_InventoryValuationReservesProvisionAccrual" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Valuation Reserves, Provision (Accrual) </link:label>
<link:label id="lab_efoi_InventoryValuationReservesProvisionAccrual_documentation_en-US" xlink:label="lab_efoi_InventoryValuationReservesProvisionAccrual" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Valuation Reserves, Provision (Accrual) </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_InventoryValuationReservesProvisionAccrual" xlink:href="efoi-20201231.xsd#efoi_InventoryValuationReservesProvisionAccrual"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_InventoryValuationReservesProvisionAccrual" xlink:to="lab_efoi_InventoryValuationReservesProvisionAccrual" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeasePrincipalPayments_515c5ab4-8c8c-4a3f-b082-c61083510586_negatedLabel_en-US" xlink:label="lab_us-gaap_FinanceLeasePrincipalPayments" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Principal payments under finance lease obligations </link:label>
<link:label id="lab_us-gaap_FinanceLeasePrincipalPayments_10815d86-c306-48a3-9d23-f86105837775_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeasePrincipalPayments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Financing cash flows from finance leases </link:label>
<link:label id="lab_us-gaap_FinanceLeasePrincipalPayments_label_en-US" xlink:label="lab_us-gaap_FinanceLeasePrincipalPayments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Principal Payments </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeasePrincipalPayments" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeasePrincipalPayments"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeasePrincipalPayments" xlink:to="lab_us-gaap_FinanceLeasePrincipalPayments" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_214de38c-0d63-4c40-ac56-a13ce724e838_terseLabel_en-US" xlink:label="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock-based compensation </link:label>
<link:label id="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_label_en-US" xlink:label="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> APIC, Share-based Payment Arrangement, Increase for Cost Recognition </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:to="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_080f471f-898f-459d-8188-79543daf8dae_terseLabel_en-US" xlink:label="lab_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Valuation allowance for deferred tax assets </link:label>
<link:label id="lab_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_label_en-US" xlink:label="lab_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" xlink:to="lab_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_eddf6122-b6cc-4b48-b11d-65b2e711638a_terseLabel_en-US" xlink:label="lab_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effect of exchange rate changes on cash </link:label>
<link:label id="lab_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_label_en-US" xlink:label="lab_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:to="lab_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RelatedPartyTransactionAmountsOfTransaction_92e39f9d-3b59-4579-815f-a60cfee6b204_terseLabel_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionAmountsOfTransaction" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amount invested </link:label>
<link:label id="lab_us-gaap_RelatedPartyTransactionAmountsOfTransaction_label_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionAmountsOfTransaction" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party Transaction, Amounts of Transaction </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction" xlink:to="lab_us-gaap_RelatedPartyTransactionAmountsOfTransaction" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ExercisePriceRangeFiveMember_d925b1fb-a9a3-4700-a307-105c1dc8d609_terseLabel_en-US" xlink:label="lab_efoi_ExercisePriceRangeFiveMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise price, range five </link:label>
<link:label id="lab_efoi_ExercisePriceRangeFiveMember_label_en-US" xlink:label="lab_efoi_ExercisePriceRangeFiveMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise Price Range Five [Member] </link:label>
<link:label id="lab_efoi_ExercisePriceRangeFiveMember_documentation_en-US" xlink:label="lab_efoi_ExercisePriceRangeFiveMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise Price Range Five </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ExercisePriceRangeFiveMember" xlink:href="efoi-20201231.xsd#efoi_ExercisePriceRangeFiveMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ExercisePriceRangeFiveMember" xlink:to="lab_efoi_ExercisePriceRangeFiveMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_13bd8799-622f-4979-a9bc-34f7738a06a5_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expired (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_InventoryNet_d411bfe3-5c07-467b-abda-2c05df0cef24_terseLabel_en-US" xlink:label="lab_us-gaap_InventoryNet" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventories, net </link:label>
<link:label id="lab_us-gaap_InventoryNet_d2bfd565-8593-4a83-af81-880b40255f69_totalLabel_en-US" xlink:label="lab_us-gaap_InventoryNet" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventories, net </link:label>
<link:label id="lab_us-gaap_InventoryNet_label_en-US" xlink:label="lab_us-gaap_InventoryNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory, Net </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryNet"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InventoryNet" xlink:to="lab_us-gaap_InventoryNet" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AdvertisingExpense_a56816d2-b660-4317-940b-10ad85e0af63_terseLabel_en-US" xlink:label="lab_us-gaap_AdvertisingExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Advertising expense </link:label>
<link:label id="lab_us-gaap_AdvertisingExpense_label_en-US" xlink:label="lab_us-gaap_AdvertisingExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Advertising Expense </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvertisingExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdvertisingExpense"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdvertisingExpense" xlink:to="lab_us-gaap_AdvertisingExpense" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeasesOperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract_6630b651-000a-48de-9170-f97aa9ad47d8_terseLabel_en-US" xlink:label="lab_efoi_RestructuredLeasesOperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases </link:label>
<link:label id="lab_efoi_RestructuredLeasesOperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract_label_en-US" xlink:label="lab_efoi_RestructuredLeasesOperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Operating Lease Liabilities, Payments, Due, Rolling Maturity [Abstract] </link:label>
<link:label id="lab_efoi_RestructuredLeasesOperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract_documentation_en-US" xlink:label="lab_efoi_RestructuredLeasesOperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Operating Lease Liabilities, Payments, Due, Rolling Maturity [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeasesOperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeasesOperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeasesOperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract" xlink:to="lab_efoi_RestructuredLeasesOperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SharePrice_fd547525-6417-42f6-9549-4b29a2f88d9a_terseLabel_en-US" xlink:label="lab_us-gaap_SharePrice" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock price (in dollars per share) </link:label>
<link:label id="lab_us-gaap_SharePrice_label_en-US" xlink:label="lab_us-gaap_SharePrice" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share Price </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharePrice"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharePrice" xlink:to="lab_us-gaap_SharePrice" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_4a82a549-a5a0-4d9e-8884-5d037b1cdf76_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] </link:label>
<link:label id="lab_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_label_en-US" xlink:label="lab_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:to="lab_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ConcentrationRiskPercentage1_f445ef61-7efc-4fd7-8088-86fd6db4db65_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskPercentage1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration risk </link:label>
<link:label id="lab_us-gaap_ConcentrationRiskPercentage1_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskPercentage1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk, Percentage </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskPercentage1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskPercentage1" xlink:to="lab_us-gaap_ConcentrationRiskPercentage1" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo_6c28fe5b-0e5b-4a28-99ee-65bf66e23981_terseLabel_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2022 </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo_label_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due In Rolling Year Two </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo_documentation_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Two </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:to="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:type="arc" order="1"/>
<link:label id="lab_srt_SegmentGeographicalDomain_d396190a-61bb-4d92-bfdb-726e40569e5b_terseLabel_en-US" xlink:label="lab_srt_SegmentGeographicalDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Geographical [Domain] </link:label>
<link:label id="lab_srt_SegmentGeographicalDomain_label_en-US" xlink:label="lab_srt_SegmentGeographicalDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Geographical [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_SegmentGeographicalDomain" xlink:to="lab_srt_SegmentGeographicalDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_99a2b573-5634-4976-996f-e67e710df726_terseLabel_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vesting periods </link:label>
<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_9ba8e087-2e15-4d15-ae84-0161938b2bd2_verboseLabel_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period </link:label>
<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_label_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:to="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_IncreaseDecreaseInInventoryReserves_df87eee0-c647-45f2-b844-c697a29c1c35_negatedTerseLabel_en-US" xlink:label="lab_efoi_IncreaseDecreaseInInventoryReserves" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Provision for slow-moving and obsolete inventories </link:label>
<link:label id="lab_efoi_IncreaseDecreaseInInventoryReserves_label_en-US" xlink:label="lab_efoi_IncreaseDecreaseInInventoryReserves" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) In Inventory Reserves </link:label>
<link:label id="lab_efoi_IncreaseDecreaseInInventoryReserves_documentation_en-US" xlink:label="lab_efoi_IncreaseDecreaseInInventoryReserves" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) In Inventory Reserves </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_IncreaseDecreaseInInventoryReserves" xlink:href="efoi-20201231.xsd#efoi_IncreaseDecreaseInInventoryReserves"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_IncreaseDecreaseInInventoryReserves" xlink:to="lab_efoi_IncreaseDecreaseInInventoryReserves" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DeferredTaxAssetsLeasingArrangements_6a5bb236-a445-4eac-ace5-015678760a57_terseLabel_en-US" xlink:label="lab_efoi_DeferredTaxAssetsLeasingArrangements" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease liabilities </link:label>
<link:label id="lab_efoi_DeferredTaxAssetsLeasingArrangements_label_en-US" xlink:label="lab_efoi_DeferredTaxAssetsLeasingArrangements" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Leasing Arrangements </link:label>
<link:label id="lab_efoi_DeferredTaxAssetsLeasingArrangements_documentation_en-US" xlink:label="lab_efoi_DeferredTaxAssetsLeasingArrangements" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Leasing Arrangements </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DeferredTaxAssetsLeasingArrangements" xlink:href="efoi-20201231.xsd#efoi_DeferredTaxAssetsLeasingArrangements"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DeferredTaxAssetsLeasingArrangements" xlink:to="lab_efoi_DeferredTaxAssetsLeasingArrangements" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LongTermPurchaseCommitmentAmount_7b30aa7c-e51b-4a09-b5ce-4add70f1dd70_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermPurchaseCommitmentAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Purchase commitment </link:label>
<link:label id="lab_us-gaap_LongTermPurchaseCommitmentAmount_label_en-US" xlink:label="lab_us-gaap_LongTermPurchaseCommitmentAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term Purchase Commitment, Amount </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentAmount" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermPurchaseCommitmentAmount"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentAmount" xlink:to="lab_us-gaap_LongTermPurchaseCommitmentAmount" xlink:type="arc" order="1"/>
<link:label id="lab_srt_ValuationAndQualifyingAccountsDisclosureLineItems_c6a2a6f3-6a8f-4554-9dcd-7f230d066f3d_terseLabel_en-US" xlink:label="lab_srt_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] </link:label>
<link:label id="lab_srt_ValuationAndQualifyingAccountsDisclosureLineItems_label_en-US" xlink:label="lab_srt_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ValuationAndQualifyingAccountsDisclosureLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:to="lab_srt_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StatementLineItems_fffe3e66-5a29-406f-93de-77a7f2119ea2_terseLabel_en-US" xlink:label="lab_us-gaap_StatementLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement [Line Items] </link:label>
<link:label id="lab_us-gaap_StatementLineItems_label_en-US" xlink:label="lab_us-gaap_StatementLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementLineItems" xlink:to="lab_us-gaap_StatementLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_srt_ScenarioForecastMember_3696ac8b-15b5-43df-9aa3-5f3930b0aa2d_terseLabel_en-US" xlink:label="lab_srt_ScenarioForecastMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Scenario, forecast </link:label>
<link:label id="lab_srt_ScenarioForecastMember_label_en-US" xlink:label="lab_srt_ScenarioForecastMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forecast [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioForecastMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ScenarioForecastMember" xlink:to="lab_srt_ScenarioForecastMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ClassOfStockDomain_e956d740-1839-4068-a9f4-bf8cd24fb0bd_terseLabel_en-US" xlink:label="lab_us-gaap_ClassOfStockDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Stock [Domain] </link:label>
<link:label id="lab_us-gaap_ClassOfStockDomain_label_en-US" xlink:label="lab_us-gaap_ClassOfStockDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Stock [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="lab_us-gaap_ClassOfStockDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EarningsPerShareBasicAndDilutedAbstract_0a636f80-f0fa-47f3-ab75-a09a4e784d09_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasicAndDilutedAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Denominator: </link:label>
<link:label id="lab_us-gaap_EarningsPerShareBasicAndDilutedAbstract_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasicAndDilutedAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share, Basic and Diluted [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasicAndDilutedAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract" xlink:to="lab_us-gaap_EarningsPerShareBasicAndDilutedAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityVoluntaryFilers_742c307e-09ff-4ae2-9fff-7def9e9476c7_terseLabel_en-US" xlink:label="lab_dei_EntityVoluntaryFilers" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Voluntary Filers </link:label>
<link:label id="lab_dei_EntityVoluntaryFilers_label_en-US" xlink:label="lab_dei_EntityVoluntaryFilers" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Voluntary Filers </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityVoluntaryFilers" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityVoluntaryFilers"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityVoluntaryFilers" xlink:to="lab_dei_EntityVoluntaryFilers" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StatementTable_8808d506-89f4-4802-bc20-acdd35d245ef_terseLabel_en-US" xlink:label="lab_us-gaap_StatementTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement [Table] </link:label>
<link:label id="lab_us-gaap_StatementTable_label_en-US" xlink:label="lab_us-gaap_StatementTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementTable" xlink:to="lab_us-gaap_StatementTable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredFinanceCostsCurrentNet_22fb8725-c8c6-49c1-98a8-c403d1c279e0_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredFinanceCostsCurrentNet" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other </link:label>
<link:label id="lab_us-gaap_DeferredFinanceCostsCurrentNet_label_en-US" xlink:label="lab_us-gaap_DeferredFinanceCostsCurrentNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Issuance Costs, Current, Net </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsCurrentNet" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredFinanceCostsCurrentNet"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredFinanceCostsCurrentNet" xlink:to="lab_us-gaap_DeferredFinanceCostsCurrentNet" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ImpairmentEffectsOnEarningsPerShareLineItems_1f02b8b8-11d1-487d-9a5e-eea1a63cad84_terseLabel_en-US" xlink:label="lab_us-gaap_ImpairmentEffectsOnEarningsPerShareLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Impairment Effects on Earnings Per Share [Line Items] </link:label>
<link:label id="lab_us-gaap_ImpairmentEffectsOnEarningsPerShareLineItems_label_en-US" xlink:label="lab_us-gaap_ImpairmentEffectsOnEarningsPerShareLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Impairment Effects on Earnings Per Share [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentEffectsOnEarningsPerShareLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ImpairmentEffectsOnEarningsPerShareLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ImpairmentEffectsOnEarningsPerShareLineItems" xlink:to="lab_us-gaap_ImpairmentEffectsOnEarningsPerShareLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StandardProductWarrantyPolicy_083ee4d9-d9f3-42c8-baae-3af509414a54_terseLabel_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyPolicy" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product warranties </link:label>
<link:label id="lab_us-gaap_StandardProductWarrantyPolicy_label_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyPolicy" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Standard Product Warranty, Policy [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyPolicy" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StandardProductWarrantyPolicy"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StandardProductWarrantyPolicy" xlink:to="lab_us-gaap_StandardProductWarrantyPolicy" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_TypeOfRestructuringDomain_bae50ba8-5a47-44a7-b7cc-479669080e70_terseLabel_en-US" xlink:label="lab_us-gaap_TypeOfRestructuringDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Type of Restructuring [Domain] </link:label>
<link:label id="lab_us-gaap_TypeOfRestructuringDomain_label_en-US" xlink:label="lab_us-gaap_TypeOfRestructuringDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Type of Restructuring [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfRestructuringDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TypeOfRestructuringDomain" xlink:to="lab_us-gaap_TypeOfRestructuringDomain" xlink:type="arc" order="1"/>
<link:label id="lab_srt_RangeAxis_8212e834-876f-483a-be1a-0385615473bf_terseLabel_en-US" xlink:label="lab_srt_RangeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statistical Measurement [Axis] </link:label>
<link:label id="lab_srt_RangeAxis_label_en-US" xlink:label="lab_srt_RangeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statistical Measurement [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_RangeAxis" xlink:to="lab_srt_RangeAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CreditFacilityAxis_2e29bbcb-38ea-4310-9aad-5b9183322726_terseLabel_en-US" xlink:label="lab_us-gaap_CreditFacilityAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Facility [Axis] </link:label>
<link:label id="lab_us-gaap_CreditFacilityAxis_label_en-US" xlink:label="lab_us-gaap_CreditFacilityAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Facility [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CreditFacilityAxis" xlink:to="lab_us-gaap_CreditFacilityAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract_df87cc33-7360-4841-a08f-3c767bbc191f_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Leases </link:label>
<link:label id="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, Payment, Due, Rolling Maturity [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract" xlink:to="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueRollingMaturityAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PreferredStockSharesIssued_e72fe425-a5f6-4a3e-8d01-a2c47db0c942_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockSharesIssued" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred stock, shares issued </link:label>
<link:label id="lab_us-gaap_PreferredStockSharesIssued_label_en-US" xlink:label="lab_us-gaap_PreferredStockSharesIssued" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred Stock, Shares Issued </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockSharesIssued"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredStockSharesIssued" xlink:to="lab_us-gaap_PreferredStockSharesIssued" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeasesOperatingLeasePayments_4995c9e4-6df8-43ec-95bb-9bb4da3bc5ef_terseLabel_en-US" xlink:label="lab_efoi_RestructuredLeasesOperatingLeasePayments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating cash flows from restructured leases </link:label>
<link:label id="lab_efoi_RestructuredLeasesOperatingLeasePayments_label_en-US" xlink:label="lab_efoi_RestructuredLeasesOperatingLeasePayments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Operating Lease, Payments </link:label>
<link:label id="lab_efoi_RestructuredLeasesOperatingLeasePayments_documentation_en-US" xlink:label="lab_efoi_RestructuredLeasesOperatingLeasePayments" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Operating Lease, Payments </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeasesOperatingLeasePayments" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeasesOperatingLeasePayments"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeasesOperatingLeasePayments" xlink:to="lab_efoi_RestructuredLeasesOperatingLeasePayments" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceived_1627a1c9-69d9-49c4-bc42-2feb0b08ea98_negatedTotalLabel_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceived" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total future undiscounted lease payments </link:label>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceived_label_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceived" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessor, Operating Lease, Payments to be Received </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceived"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived" xlink:to="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceived" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeasesOperatingLeaseWeightedAverageRemainingLeaseTerm_a4959b33-6e77-477d-925c-16e89782a9c8_terseLabel_en-US" xlink:label="lab_efoi_RestructuredLeasesOperatingLeaseWeightedAverageRemainingLeaseTerm" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured lease, weighted average remaining lease term </link:label>
<link:label id="lab_efoi_RestructuredLeasesOperatingLeaseWeightedAverageRemainingLeaseTerm_label_en-US" xlink:label="lab_efoi_RestructuredLeasesOperatingLeaseWeightedAverageRemainingLeaseTerm" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Operating Lease, Weighted Average Remaining Lease Term </link:label>
<link:label id="lab_efoi_RestructuredLeasesOperatingLeaseWeightedAverageRemainingLeaseTerm_documentation_en-US" xlink:label="lab_efoi_RestructuredLeasesOperatingLeaseWeightedAverageRemainingLeaseTerm" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Operating Lease, Weighted Average Remaining Lease Term </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeasesOperatingLeaseWeightedAverageRemainingLeaseTerm" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeasesOperatingLeaseWeightedAverageRemainingLeaseTerm"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeasesOperatingLeaseWeightedAverageRemainingLeaseTerm" xlink:to="lab_efoi_RestructuredLeasesOperatingLeaseWeightedAverageRemainingLeaseTerm" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProceedsFromLoanOriginations1_b7cc3656-5297-4977-8454-491c6c0b5157_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromLoanOriginations1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from loan origination </link:label>
<link:label id="lab_us-gaap_ProceedsFromLoanOriginations1_label_en-US" xlink:label="lab_us-gaap_ProceedsFromLoanOriginations1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Loan Originations </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLoanOriginations1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromLoanOriginations1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromLoanOriginations1" xlink:to="lab_us-gaap_ProceedsFromLoanOriginations1" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_BrilliantStartEnterpriseInc.Member_05be4f68-266e-466b-9887-65b5403ae092_terseLabel_en-US" xlink:label="lab_efoi_BrilliantStartEnterpriseInc.Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Brilliant Start Enterprise, Inc. </link:label>
<link:label id="lab_efoi_BrilliantStartEnterpriseInc.Member_label_en-US" xlink:label="lab_efoi_BrilliantStartEnterpriseInc.Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Brilliant Start Enterprise, Inc. [Member] </link:label>
<link:label id="lab_efoi_BrilliantStartEnterpriseInc.Member_documentation_en-US" xlink:label="lab_efoi_BrilliantStartEnterpriseInc.Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Brilliant Start Enterprise, Inc. [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_BrilliantStartEnterpriseInc.Member" xlink:href="efoi-20201231.xsd#efoi_BrilliantStartEnterpriseInc.Member"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_BrilliantStartEnterpriseInc.Member" xlink:to="lab_efoi_BrilliantStartEnterpriseInc.Member" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_acf7deb6-f0e4-4218-9aad-44fb852330ea_terseLabel_en-US" xlink:label="lab_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise price of warrants (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_label_en-US" xlink:label="lab_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Warrant or Right, Exercise Price of Warrants or Rights </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:to="lab_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFive_1e2a9aee-a81b-4ae5-966d-11e22248a393_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFive" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2025 </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFive_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Payments, Due in Rolling Year Five </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFive" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFive"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFive" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFive" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringAndRelatedActivitiesAbstract_ca4fa286-fdc4-4bc2-8810-8417a66e097c_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringAndRelatedActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring and Related Activities [Abstract] </link:label>
<link:label id="lab_us-gaap_RestructuringAndRelatedActivitiesAbstract_label_en-US" xlink:label="lab_us-gaap_RestructuringAndRelatedActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring and Related Activities [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedActivitiesAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringAndRelatedActivitiesAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringAndRelatedActivitiesAbstract" xlink:to="lab_us-gaap_RestructuringAndRelatedActivitiesAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_StandardProductWarrantyNumberofYears_b0619f34-feac-49f0-8b6b-5bd6594a4d5d_terseLabel_en-US" xlink:label="lab_efoi_StandardProductWarrantyNumberofYears" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Standard Product Warranty, Number of Years </link:label>
<link:label id="lab_efoi_StandardProductWarrantyNumberofYears_label_en-US" xlink:label="lab_efoi_StandardProductWarrantyNumberofYears" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Standard Product Warranty, Number of Years </link:label>
<link:label id="lab_efoi_StandardProductWarrantyNumberofYears_documentation_en-US" xlink:label="lab_efoi_StandardProductWarrantyNumberofYears" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Standard Product Warranty, Number of Years </link:label>
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<link:label id="lab_us-gaap_EarningsPerShareBasicAndDiluted_ed2f2cf2-9bd2-4cd6-bd0d-0304b465a8f7_verboseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasicAndDiluted" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net loss </link:label>
<link:label id="lab_us-gaap_EarningsPerShareBasicAndDiluted_f801e7c2-f6a9-4585-a4a4-10c1b0a91779_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasicAndDiluted" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net loss per share (basic and diluted) (in dollars per share) </link:label>
<link:label id="lab_us-gaap_EarningsPerShareBasicAndDiluted_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasicAndDiluted" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share, Basic and Diluted </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDiluted" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasicAndDiluted"/>
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<link:label id="lab_dei_EntitySmallBusiness_c47a0334-5e11-4551-ab69-daf6182a9275_terseLabel_en-US" xlink:label="lab_dei_EntitySmallBusiness" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Small Business </link:label>
<link:label id="lab_dei_EntitySmallBusiness_label_en-US" xlink:label="lab_dei_EntitySmallBusiness" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Small Business </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntitySmallBusiness"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntitySmallBusiness" xlink:to="lab_dei_EntitySmallBusiness" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_OperatingLeaseRightofUseAssetIncludingRestructuredLeases_3f9f89f3-483a-4094-b4bb-2ae3d15c23d9_totalLabel_en-US" xlink:label="lab_efoi_OperatingLeaseRightofUseAssetIncludingRestructuredLeases" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease right-of-use assets, total </link:label>
<link:label id="lab_efoi_OperatingLeaseRightofUseAssetIncludingRestructuredLeases_label_en-US" xlink:label="lab_efoi_OperatingLeaseRightofUseAssetIncludingRestructuredLeases" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Right-of-Use Asset, Including Restructured Leases </link:label>
<link:label id="lab_efoi_OperatingLeaseRightofUseAssetIncludingRestructuredLeases_documentation_en-US" xlink:label="lab_efoi_OperatingLeaseRightofUseAssetIncludingRestructuredLeases" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Right-of-Use Asset, Including Restructured Leases </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_OperatingLeaseRightofUseAssetIncludingRestructuredLeases" xlink:href="efoi-20201231.xsd#efoi_OperatingLeaseRightofUseAssetIncludingRestructuredLeases"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_OperatingLeaseRightofUseAssetIncludingRestructuredLeases" xlink:to="lab_efoi_OperatingLeaseRightofUseAssetIncludingRestructuredLeases" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_31988a5e-d1d5-4ef5-9ba2-2d0f08eb79e9_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Stockholders' Equity [Roll Forward] </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Stockholders' Equity [Roll Forward] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="lab_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_UnamortizedDebtIssuanceExpense_f82c3cce-4b94-422a-8e6f-c89ea76aafb1_terseLabel_en-US" xlink:label="lab_us-gaap_UnamortizedDebtIssuanceExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unamortized net issuance costs </link:label>
<link:label id="lab_us-gaap_UnamortizedDebtIssuanceExpense_label_en-US" xlink:label="lab_us-gaap_UnamortizedDebtIssuanceExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unamortized Debt Issuance Expense </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnamortizedDebtIssuanceExpense" xlink:to="lab_us-gaap_UnamortizedDebtIssuanceExpense" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtDisclosureTextBlock_85843cde-9526-4b47-988c-6938dbd276fa_terseLabel_en-US" xlink:label="lab_us-gaap_DebtDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt </link:label>
<link:label id="lab_us-gaap_DebtDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_DebtDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Disclosure [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtDisclosureTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtDisclosureTextBlock" xlink:to="lab_us-gaap_DebtDisclosureTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_6cb9cd91-797e-4c96-9584-4b777789caaa_terseLabel_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Remaining Contractual Life (in years) </link:label>
<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_label_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
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<link:label id="lab_us-gaap_SellingGeneralAndAdministrativeExpensesMember_49f4917b-e6ad-47ec-bbd1-673b6d5d64a2_terseLabel_en-US" xlink:label="lab_us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Selling, general, and administrative </link:label>
<link:label id="lab_us-gaap_SellingGeneralAndAdministrativeExpensesMember_label_en-US" xlink:label="lab_us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Selling, General and Administrative Expenses [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:to="lab_us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:type="arc" order="1"/>
<link:label id="lab_dei_AmendmentFlag_796aa802-dc73-4860-8f73-b595844dcbd9_terseLabel_en-US" xlink:label="lab_dei_AmendmentFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amendment Flag </link:label>
<link:label id="lab_dei_AmendmentFlag_label_en-US" xlink:label="lab_dei_AmendmentFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amendment Flag </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_AmendmentFlag"/>
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<link:label id="lab_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_50d3ebe0-69f0-4d0d-817d-9c5da74ef6f2_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Earnings Per Share, Basic and Diluted </link:label>
<link:label id="lab_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock"/>
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<link:label id="lab_us-gaap_PrepaidRent_379e56f1-3feb-4453-9a9b-23134ba7b3c9_terseLabel_en-US" xlink:label="lab_us-gaap_PrepaidRent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid rent </link:label>
<link:label id="lab_us-gaap_PrepaidRent_label_en-US" xlink:label="lab_us-gaap_PrepaidRent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid Rent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidRent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrepaidRent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PrepaidRent" xlink:to="lab_us-gaap_PrepaidRent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_c4bce043-9dc1-4a01-8d7a-a5dec8fc347c_terseLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued interest and penalties related to uncertain tax positions </link:label>
<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_label_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued"/>
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<link:label id="lab_us-gaap_BusinessAcquisitionContingentConsiderationLineItems_84daf57d-71c6-4c1c-8d3d-daaf050c9c8f_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionContingentConsiderationLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition, Contingent Consideration [Line Items] </link:label>
<link:label id="lab_us-gaap_BusinessAcquisitionContingentConsiderationLineItems_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionContingentConsiderationLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition, Contingent Consideration [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionContingentConsiderationLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionContingentConsiderationLineItems"/>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_d0a873b2-3a40-43fa-84b3-af41ef617389_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of shares authorized (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeFinanceLeasesTextBlock_bdb193b1-1b34-4ac4-b1f5-416fb1cf37d9_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeFinanceLeasesTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leases </link:label>
<link:label id="lab_us-gaap_LesseeFinanceLeasesTextBlock_label_en-US" xlink:label="lab_us-gaap_LesseeFinanceLeasesTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Finance Leases [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeFinanceLeasesTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeFinanceLeasesTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeFinanceLeasesTextBlock" xlink:to="lab_us-gaap_LesseeFinanceLeasesTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ResearchAndDevelopmentExpensePolicy_0eebaf03-c713-4645-bfc2-1841f7fd6c60_terseLabel_en-US" xlink:label="lab_us-gaap_ResearchAndDevelopmentExpensePolicy" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product development </link:label>
<link:label id="lab_us-gaap_ResearchAndDevelopmentExpensePolicy_label_en-US" xlink:label="lab_us-gaap_ResearchAndDevelopmentExpensePolicy" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Research and Development Expense, Policy [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpensePolicy" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentExpensePolicy"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ResearchAndDevelopmentExpensePolicy" xlink:to="lab_us-gaap_ResearchAndDevelopmentExpensePolicy" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityAmountAvailableBasedOnQualifiedAccounts_595e3bda-2274-49bc-b3f6-85b83a979cfc_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAmountAvailableBasedOnQualifiedAccounts" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amount available under facility based on qualified accounts receivable </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAmountAvailableBasedOnQualifiedAccounts_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAmountAvailableBasedOnQualifiedAccounts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Amount Available Based On Qualified Accounts </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAmountAvailableBasedOnQualifiedAccounts_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAmountAvailableBasedOnQualifiedAccounts" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Amount Available Based On Qualified Accounts </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityAmountAvailableBasedOnQualifiedAccounts" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityAmountAvailableBasedOnQualifiedAccounts"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityAmountAvailableBasedOnQualifiedAccounts" xlink:to="lab_efoi_LineOfCreditFacilityAmountAvailableBasedOnQualifiedAccounts" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_InventoryFacilityMember_92fa1df8-f81c-49c0-a59b-284debca9585_terseLabel_en-US" xlink:label="lab_efoi_InventoryFacilityMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Facility </link:label>
<link:label id="lab_efoi_InventoryFacilityMember_label_en-US" xlink:label="lab_efoi_InventoryFacilityMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Facility [Member] </link:label>
<link:label id="lab_efoi_InventoryFacilityMember_documentation_en-US" xlink:label="lab_efoi_InventoryFacilityMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Facility </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_InventoryFacilityMember" xlink:href="efoi-20201231.xsd#efoi_InventoryFacilityMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_InventoryFacilityMember" xlink:to="lab_efoi_InventoryFacilityMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ClassOfWarrantOrRightWarrantsIssuedPricePerShare_e9fcc68b-387b-44cb-8d97-d64a1a172206_terseLabel_en-US" xlink:label="lab_efoi_ClassOfWarrantOrRightWarrantsIssuedPricePerShare" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Purchase price (in dollars per share) </link:label>
<link:label id="lab_efoi_ClassOfWarrantOrRightWarrantsIssuedPricePerShare_label_en-US" xlink:label="lab_efoi_ClassOfWarrantOrRightWarrantsIssuedPricePerShare" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class Of Warrant Or Right, Warrants Issued, Price Per Share </link:label>
<link:label id="lab_efoi_ClassOfWarrantOrRightWarrantsIssuedPricePerShare_documentation_en-US" xlink:label="lab_efoi_ClassOfWarrantOrRightWarrantsIssuedPricePerShare" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class Of Warrant Or Right, Warrants Issued, Price Per Share </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ClassOfWarrantOrRightWarrantsIssuedPricePerShare" xlink:href="efoi-20201231.xsd#efoi_ClassOfWarrantOrRightWarrantsIssuedPricePerShare"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ClassOfWarrantOrRightWarrantsIssuedPricePerShare" xlink:to="lab_efoi_ClassOfWarrantOrRightWarrantsIssuedPricePerShare" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_ac08fada-1973-4989-892b-cf9e0a4403e9_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of shares available for grant (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ConvertibleNotesPayableCurrent_f3393da3-e3f9-42e6-a21b-47237ce4c37a_terseLabel_en-US" xlink:label="lab_us-gaap_ConvertibleNotesPayableCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Convertible notes </link:label>
<link:label id="lab_us-gaap_ConvertibleNotesPayableCurrent_label_en-US" xlink:label="lab_us-gaap_ConvertibleNotesPayableCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Convertible Notes Payable, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleNotesPayableCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConvertibleNotesPayableCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConvertibleNotesPayableCurrent" xlink:to="lab_us-gaap_ConvertibleNotesPayableCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OtherAccruedLiabilitiesCurrent_6f23d03a-59fa-4777-a87d-ff66d9e1c943_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAccruedLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued liabilities </link:label>
<link:label id="lab_us-gaap_OtherAccruedLiabilitiesCurrent_label_en-US" xlink:label="lab_us-gaap_OtherAccruedLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Accrued Liabilities, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAccruedLiabilitiesCurrent" xlink:to="lab_us-gaap_OtherAccruedLiabilitiesCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProductWarrantyLiabilityLineItems_8fd781ec-960b-4195-b72a-5afcba109a87_terseLabel_en-US" xlink:label="lab_us-gaap_ProductWarrantyLiabilityLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product Warranty Liability [Line Items] </link:label>
<link:label id="lab_us-gaap_ProductWarrantyLiabilityLineItems_label_en-US" xlink:label="lab_us-gaap_ProductWarrantyLiabilityLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product Warranty Liability [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductWarrantyLiabilityLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProductWarrantyLiabilityLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProductWarrantyLiabilityLineItems" xlink:to="lab_us-gaap_ProductWarrantyLiabilityLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RepaymentsOfDebt_38232e13-00d3-4518-9a64-7d2b4c4bb6bd_terseLabel_en-US" xlink:label="lab_us-gaap_RepaymentsOfDebt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Repayments of debt </link:label>
<link:label id="lab_us-gaap_RepaymentsOfDebt_label_en-US" xlink:label="lab_us-gaap_RepaymentsOfDebt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Repayments of Debt </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfDebt"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RepaymentsOfDebt" xlink:to="lab_us-gaap_RepaymentsOfDebt" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FairValueMeasurementPolicyPolicyTextBlock_6c662b56-78fd-4c2e-83c4-6b9a2ee2d54d_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueMeasurementPolicyPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Financial Instruments </link:label>
<link:label id="lab_us-gaap_FairValueMeasurementPolicyPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_FairValueMeasurementPolicyPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value Measurement, Policy [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementPolicyPolicyTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementPolicyPolicyTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueMeasurementPolicyPolicyTextBlock" xlink:to="lab_us-gaap_FairValueMeasurementPolicyPolicyTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_cd88f543-02f5-446d-b39c-6dd4dab1e158_totalLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net cash used in operating activities </link:label>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_4eb7bfd6-c93c-4db1-9f04-54717ea09278_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net cash used in operating activities </link:label>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Operating Activities </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityCentralIndexKey_1b4a202d-c20c-4008-819d-81a0d51239b3_terseLabel_en-US" xlink:label="lab_dei_EntityCentralIndexKey" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Central Index Key </link:label>
<link:label id="lab_dei_EntityCentralIndexKey_label_en-US" xlink:label="lab_dei_EntityCentralIndexKey" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Central Index Key </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityCentralIndexKey"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityCentralIndexKey" xlink:to="lab_dei_EntityCentralIndexKey" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RelatedPartyDomain_1dfd0e62-e4c8-4d64-86d9-206435aceadb_terseLabel_en-US" xlink:label="lab_us-gaap_RelatedPartyDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party [Domain] </link:label>
<link:label id="lab_us-gaap_RelatedPartyDomain_label_en-US" xlink:label="lab_us-gaap_RelatedPartyDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RelatedPartyDomain" xlink:to="lab_us-gaap_RelatedPartyDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock_f141d50d-dc3a-469d-a898-696f9d55360a_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring </link:label>
<link:label id="lab_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring and Related Activities Disclosure [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock" xlink:to="lab_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RelatedPartyTransactionLineItems_af9c0756-1171-418e-8c94-405b558e1c23_terseLabel_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party Transaction [Line Items] </link:label>
<link:label id="lab_us-gaap_RelatedPartyTransactionLineItems_label_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party Transaction [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems" xlink:to="lab_us-gaap_RelatedPartyTransactionLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_srt_StatementGeographicalAxis_90b04f3c-10c7-43cc-8afc-9dd8ec7a6ede_terseLabel_en-US" xlink:label="lab_srt_StatementGeographicalAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Geographical [Axis] </link:label>
<link:label id="lab_srt_StatementGeographicalAxis_label_en-US" xlink:label="lab_srt_StatementGeographicalAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Geographical [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementGeographicalAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_StatementGeographicalAxis" xlink:to="lab_srt_StatementGeographicalAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SubsequentEventsTextBlock_84382ba1-5f26-4ab7-b5a5-ec07c891dba1_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventsTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Events </link:label>
<link:label id="lab_us-gaap_SubsequentEventsTextBlock_label_en-US" xlink:label="lab_us-gaap_SubsequentEventsTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Events [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventsTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventsTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventsTextBlock" xlink:to="lab_us-gaap_SubsequentEventsTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_78658ca8-6dcd-44aa-ad85-e152e19cf32e_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Shares issued in the period (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsRollingMaturityAbstract_01a5a0c1-6636-4727-a95c-d26006bd243d_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsRollingMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsRollingMaturityAbstract_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsRollingMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Payment, Due, Rolling Maturity [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsRollingMaturityAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilitiesPaymentsRollingMaturityAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsRollingMaturityAbstract" xlink:to="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsRollingMaturityAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FairValueAdjustmentOfWarrants_32706d5b-f199-47f9-b48b-613bca8151bd_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueAdjustmentOfWarrants" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss from change in fair value of warrants </link:label>
<link:label id="lab_us-gaap_FairValueAdjustmentOfWarrants_937d347a-237f-4036-a7ad-0e44c96fcb69_verboseLabel_en-US" xlink:label="lab_us-gaap_FairValueAdjustmentOfWarrants" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Change in fair value of warrant liabilities </link:label>
<link:label id="lab_us-gaap_FairValueAdjustmentOfWarrants_label_en-US" xlink:label="lab_us-gaap_FairValueAdjustmentOfWarrants" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value Adjustment of Warrants </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAdjustmentOfWarrants" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAdjustmentOfWarrants"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueAdjustmentOfWarrants" xlink:to="lab_us-gaap_FairValueAdjustmentOfWarrants" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StatementOfCashFlowsAbstract_c2c125f2-52d1-43fb-9511-3371658e7368_terseLabel_en-US" xlink:label="lab_us-gaap_StatementOfCashFlowsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Cash Flows [Abstract] </link:label>
<link:label id="lab_us-gaap_StatementOfCashFlowsAbstract_label_en-US" xlink:label="lab_us-gaap_StatementOfCashFlowsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Cash Flows [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfCashFlowsAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementOfCashFlowsAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract" xlink:to="lab_us-gaap_StatementOfCashFlowsAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis_63534425-914b-432a-9db3-cb2c1fc67e22_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment, Type [Axis] </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Lived Tangible Asset [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock_9839c946-f90a-44d3-83e1-7e47f3d5c57d_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary of Restricted Stock Activity </link:label>
<link:label id="lab_us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfSharebasedCompensationRestrictedStockAndRestrictedStockUnitsActivityTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ValuationAllowancesAndReservesBalance_ffc91e12-6124-436a-a3bf-6db447205ee9_periodStartLabel_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesBalance" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Beginning Balance </link:label>
<link:label id="lab_us-gaap_ValuationAllowancesAndReservesBalance_a456509f-7738-49ad-8802-78ce992a70a5_periodEndLabel_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesBalance" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ending Balance </link:label>
<link:label id="lab_us-gaap_ValuationAllowancesAndReservesBalance_label_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesBalance" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesBalance" xlink:to="lab_us-gaap_ValuationAllowancesAndReservesBalance" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock_adba974c-c226-42f1-9dbf-b7a2e1973652_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Breakdown of Product Net Sales </link:label>
<link:label id="lab_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue from External Customers by Products and Services [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock"/>
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<link:label id="lab_us-gaap_IncomeStatementLocationAxis_c86a7328-1e5d-4887-92ce-2cf4e4fa3e3d_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeStatementLocationAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Statement Location [Axis] </link:label>
<link:label id="lab_us-gaap_IncomeStatementLocationAxis_label_en-US" xlink:label="lab_us-gaap_IncomeStatementLocationAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Statement Location [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeStatementLocationAxis" xlink:to="lab_us-gaap_IncomeStatementLocationAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_67b7263d-c9a1-4b5c-95f8-b4f7b7a95fa2_terseLabel_en-US" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trade accounts receivable, allowances </link:label>
<link:label id="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_label_en-US" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, Allowance for Credit Loss, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:to="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DepositsAssetsCurrent_7e944ae3-be57-403c-833b-f481652c65da_terseLabel_en-US" xlink:label="lab_us-gaap_DepositsAssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Short-term deposits </link:label>
<link:label id="lab_us-gaap_DepositsAssetsCurrent_label_en-US" xlink:label="lab_us-gaap_DepositsAssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deposits Assets, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsAssetsCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DepositsAssetsCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DepositsAssetsCurrent" xlink:to="lab_us-gaap_DepositsAssetsCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_dd1e9775-2185-4c5f-830b-6aee4d217f1d_terseLabel_en-US" xlink:label="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Remaining Contractual Life (in years) </link:label>
<link:label id="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_label_en-US" xlink:label="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2"/>
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<link:label id="lab_dei_EntityCommonStockSharesOutstanding_cb298eb3-a90e-494b-97fd-f91653a9194a_terseLabel_en-US" xlink:label="lab_dei_EntityCommonStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Common Stock, Shares Outstanding </link:label>
<link:label id="lab_dei_EntityCommonStockSharesOutstanding_label_en-US" xlink:label="lab_dei_EntityCommonStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Common Stock, Shares Outstanding </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityCommonStockSharesOutstanding"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityCommonStockSharesOutstanding" xlink:to="lab_dei_EntityCommonStockSharesOutstanding" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncomeStatementLocationDomain_21f9ffcf-5f75-483b-bbe1-efe054845e4f_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeStatementLocationDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Statement Location [Domain] </link:label>
<link:label id="lab_us-gaap_IncomeStatementLocationDomain_label_en-US" xlink:label="lab_us-gaap_IncomeStatementLocationDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Statement Location [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeStatementLocationDomain" xlink:to="lab_us-gaap_IncomeStatementLocationDomain" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DSeriesLampsMember_27110193-3ce4-4131-b719-3fcd3e2e44bc_terseLabel_en-US" xlink:label="lab_efoi_DSeriesLampsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> D-Series Lamps </link:label>
<link:label id="lab_efoi_DSeriesLampsMember_label_en-US" xlink:label="lab_efoi_DSeriesLampsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> D-Series Lamps [Member] </link:label>
<link:label id="lab_efoi_DSeriesLampsMember_documentation_en-US" xlink:label="lab_efoi_DSeriesLampsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> D-Series Lamps </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DSeriesLampsMember" xlink:href="efoi-20201231.xsd#efoi_DSeriesLampsMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DSeriesLampsMember" xlink:to="lab_efoi_DSeriesLampsMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StateAndLocalJurisdictionMember_920528ee-56f3-4a11-b48d-3512e91fd8b8_terseLabel_en-US" xlink:label="lab_us-gaap_StateAndLocalJurisdictionMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> State and Local </link:label>
<link:label id="lab_us-gaap_StateAndLocalJurisdictionMember_label_en-US" xlink:label="lab_us-gaap_StateAndLocalJurisdictionMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> State and Local Jurisdiction [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember" xlink:to="lab_us-gaap_StateAndLocalJurisdictionMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_74efe99f-9205-4616-8836-531273d222c1_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash flows from financing activities: </link:label>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Financing Activities [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SellingGeneralAndAdministrativeExpense_8d977dec-6c35-4fc6-a0a2-9d1625edee08_terseLabel_en-US" xlink:label="lab_us-gaap_SellingGeneralAndAdministrativeExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Selling, general, and administrative </link:label>
<link:label id="lab_us-gaap_SellingGeneralAndAdministrativeExpense_label_en-US" xlink:label="lab_us-gaap_SellingGeneralAndAdministrativeExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Selling, General and Administrative Expense </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SellingGeneralAndAdministrativeExpense" xlink:to="lab_us-gaap_SellingGeneralAndAdministrativeExpense" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock_ec9b6b5b-4bad-4f0c-b5ef-76a2628ad08c_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Prepaid and Other Current Assets </link:label>
<link:label id="lab_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock" xlink:to="lab_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockholdersEquityNoteAbstract_64fbb49e-2ea5-4788-b156-7dedc24d03ff_terseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityNoteAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stockholders' Equity Note [Abstract] </link:label>
<link:label id="lab_us-gaap_StockholdersEquityNoteAbstract_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityNoteAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stockholders' Equity Note [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityNoteAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityNoteAbstract" xlink:to="lab_us-gaap_StockholdersEquityNoteAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfRevenueFromExternalCustomersAttributedToForeignCountriesByGeographicAreaTextBlock_296cd756-f2f2-4074-998f-ca743206dc2c_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfRevenueFromExternalCustomersAttributedToForeignCountriesByGeographicAreaTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Geographic Summary of Net Sales </link:label>
<link:label id="lab_us-gaap_ScheduleOfRevenueFromExternalCustomersAttributedToForeignCountriesByGeographicAreaTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfRevenueFromExternalCustomersAttributedToForeignCountriesByGeographicAreaTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenueFromExternalCustomersAttributedToForeignCountriesByGeographicAreaTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfRevenueFromExternalCustomersAttributedToForeignCountriesByGeographicAreaTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfRevenueFromExternalCustomersAttributedToForeignCountriesByGeographicAreaTextBlock" xlink:to="lab_us-gaap_ScheduleOfRevenueFromExternalCustomersAttributedToForeignCountriesByGeographicAreaTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LeaseCostTableTextBlock_6209aabb-a07e-48fe-a14b-4d907146982d_terseLabel_en-US" xlink:label="lab_us-gaap_LeaseCostTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Components of Lease Cost and Supplemental Cash Flow Information </link:label>
<link:label id="lab_us-gaap_LeaseCostTableTextBlock_label_en-US" xlink:label="lab_us-gaap_LeaseCostTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease, Cost [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCostTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseCostTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeaseCostTableTextBlock" xlink:to="lab_us-gaap_LeaseCostTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OtherAssetsNoncurrent_be000a59-73c0-4147-bbe7-edb47c7dd110_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAssetsNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other assets </link:label>
<link:label id="lab_us-gaap_OtherAssetsNoncurrent_label_en-US" xlink:label="lab_us-gaap_OtherAssetsNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Assets, Noncurrent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAssetsNoncurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAssetsNoncurrent" xlink:to="lab_us-gaap_OtherAssetsNoncurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PlanNameAxis_eb6ab433-b9c2-4623-8fb8-3378ec89a236_terseLabel_en-US" xlink:label="lab_us-gaap_PlanNameAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Plan Name [Axis] </link:label>
<link:label id="lab_us-gaap_PlanNameAxis_label_en-US" xlink:label="lab_us-gaap_PlanNameAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Plan Name [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PlanNameAxis" xlink:to="lab_us-gaap_PlanNameAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SegmentReportingDisclosureTextBlock_996b97e2-5039-4faa-a77b-8af13b1c58da_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentReportingDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product and Geographic Information </link:label>
<link:label id="lab_us-gaap_SegmentReportingDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_SegmentReportingDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Reporting Disclosure [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingDisclosureTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentReportingDisclosureTextBlock" xlink:to="lab_us-gaap_SegmentReportingDisclosureTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodValueNewIssues_afe046be-1639-4e6f-a1c4-df12d1682878_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Issuance of common stock and warrants </link:label>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodValueNewIssues_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Issued During Period, Value, New Issues </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:to="lab_us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ConcentrationRiskTable_0e6edb0f-ec55-43a8-8656-ced8b2511af1_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk [Table] </link:label>
<link:label id="lab_us-gaap_ConcentrationRiskTable_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskTable" xlink:to="lab_us-gaap_ConcentrationRiskTable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_Assets_2e3d5eb2-6244-4e9d-8fa2-cb5b6c393724_totalLabel_en-US" xlink:label="lab_us-gaap_Assets" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total assets </link:label>
<link:label id="lab_us-gaap_Assets_label_en-US" xlink:label="lab_us-gaap_Assets" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Assets" xlink:to="lab_us-gaap_Assets" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RelatedPartyTransactionsDisclosureTextBlock_cd3dccb4-deec-41dc-a41b-a1e5e874c88e_terseLabel_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party Transactions </link:label>
<link:label id="lab_us-gaap_RelatedPartyTransactionsDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party Transactions Disclosure [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsDisclosureTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:to="lab_us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_srt_StatementScenarioAxis_b110ae25-25fd-4f0a-a0e2-79e76323d4af_terseLabel_en-US" xlink:label="lab_srt_StatementScenarioAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Scenario [Axis] </link:label>
<link:label id="lab_srt_StatementScenarioAxis_label_en-US" xlink:label="lab_srt_StatementScenarioAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Scenario [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_StatementScenarioAxis" xlink:to="lab_srt_StatementScenarioAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues_3e5e4580-6ad2-4911-b90b-dccf7a7c50ad_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Issuance of warrants, January 2020 </link:label>
<link:label id="lab_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues_label_en-US" xlink:label="lab_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues" xlink:to="lab_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9445101a-c5d6-4b26-9cfc-3efd10217d7b_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise Price Range [Domain] </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise Price Range [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_EmployeeStockPurchasePlan2013Member_39dba3c0-a3b9-4fad-81c7-32fa0c51cb0d_terseLabel_en-US" xlink:label="lab_efoi_EmployeeStockPurchasePlan2013Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2013 Plan </link:label>
<link:label id="lab_efoi_EmployeeStockPurchasePlan2013Member_label_en-US" xlink:label="lab_efoi_EmployeeStockPurchasePlan2013Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employee Stock Purchase Plan 2013 [Member] </link:label>
<link:label id="lab_efoi_EmployeeStockPurchasePlan2013Member_documentation_en-US" xlink:label="lab_efoi_EmployeeStockPurchasePlan2013Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Information related to the employee stock purchase plan approved in 2013. </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_EmployeeStockPurchasePlan2013Member" xlink:href="efoi-20201231.xsd#efoi_EmployeeStockPurchasePlan2013Member"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_EmployeeStockPurchasePlan2013Member" xlink:to="lab_efoi_EmployeeStockPurchasePlan2013Member" xlink:type="arc" order="1"/>
<link:label id="lab_dei_Security12bTitle_00bf2027-8dde-4104-a0f1-fedab4ead9ea_terseLabel_en-US" xlink:label="lab_dei_Security12bTitle" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Title of 12(b) Security </link:label>
<link:label id="lab_dei_Security12bTitle_label_en-US" xlink:label="lab_dei_Security12bTitle" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Title of 12(b) Security </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_Security12bTitle"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_Security12bTitle" xlink:to="lab_dei_Security12bTitle" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock_bf981ba7-98af-406e-b305-fbbcb07df100_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Accrued Current Liabilities </link:label>
<link:label id="lab_us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Accrued Liabilities [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_f3158c1c-0aa2-493d-bd4d-a6481508f25c_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair value of options issued (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_InstitutionalInvestorMember_19aa8e09-1c63-445d-bea7-32c877d8c04c_terseLabel_en-US" xlink:label="lab_efoi_InstitutionalInvestorMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Institutional Investor </link:label>
<link:label id="lab_efoi_InstitutionalInvestorMember_label_en-US" xlink:label="lab_efoi_InstitutionalInvestorMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Institutional Investor [Member] </link:label>
<link:label id="lab_efoi_InstitutionalInvestorMember_documentation_en-US" xlink:label="lab_efoi_InstitutionalInvestorMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Institutional Investor </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_InstitutionalInvestorMember" xlink:href="efoi-20201231.xsd#efoi_InstitutionalInvestorMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_InstitutionalInvestorMember" xlink:to="lab_efoi_InstitutionalInvestorMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SubsequentEventTypeAxis_86c7c5ac-5a1e-4f7a-8849-463a022573fb_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event Type [Axis] </link:label>
<link:label id="lab_us-gaap_SubsequentEventTypeAxis_label_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event Type [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventTypeAxis" xlink:to="lab_us-gaap_SubsequentEventTypeAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CostOfSalesMember_b381453c-7e9e-4399-b5f1-e49f1bc6c7fd_terseLabel_en-US" xlink:label="lab_us-gaap_CostOfSalesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cost of sales </link:label>
<link:label id="lab_us-gaap_CostOfSalesMember_label_en-US" xlink:label="lab_us-gaap_CostOfSalesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cost of Sales [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CostOfSalesMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CostOfSalesMember" xlink:to="lab_us-gaap_CostOfSalesMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ConcentrationRiskCreditRisk_ecec08c1-1720-49ad-b4ba-0a6e93b3db7e_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskCreditRisk" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Certain risks and concentrations </link:label>
<link:label id="lab_us-gaap_ConcentrationRiskCreditRisk_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskCreditRisk" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk, Credit Risk, Policy [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskCreditRisk" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskCreditRisk"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskCreditRisk" xlink:to="lab_us-gaap_ConcentrationRiskCreditRisk" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock_4ec95bd0-85ad-4dfb-bce6-043f41e89b5f_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Future Maturities of Finance Lease Liabilities </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Fiscal Year Maturity [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock" xlink:to="lab_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_InterestExpense_d30ea89c-278a-482e-a3c6-295cae0844ec_terseLabel_en-US" xlink:label="lab_us-gaap_InterestExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest expense </link:label>
<link:label id="lab_us-gaap_InterestExpense_label_en-US" xlink:label="lab_us-gaap_InterestExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest Expense </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestExpense"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestExpense" xlink:to="lab_us-gaap_InterestExpense" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_PoolAndCommercialProductsMember_8b231bfa-a907-4043-802e-e8bb340f0bf6_verboseLabel_en-US" xlink:label="lab_efoi_PoolAndCommercialProductsMember" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commercial products </link:label>
<link:label id="lab_efoi_PoolAndCommercialProductsMember_label_en-US" xlink:label="lab_efoi_PoolAndCommercialProductsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pool And Commercial Products [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_PoolAndCommercialProductsMember" xlink:href="efoi-20201231.xsd#efoi_PoolAndCommercialProductsMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_PoolAndCommercialProductsMember" xlink:to="lab_efoi_PoolAndCommercialProductsMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_72dc3cec-331b-4e50-8e50-6873b6b41f65_terseLabel_en-US" xlink:label="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Exercise Price (in dollars per share) </link:label>
<link:label id="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_label_en-US" xlink:label="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Exercise Price </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:to="lab_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_8634f028-a2ae-4b78-b6ab-2ebc27e49223_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Components of Benefits from Income Taxes </link:label>
<link:label id="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_srt_ProductOrServiceAxis_da421ead-06a5-4e9f-9b9d-29042a7d308f_terseLabel_en-US" xlink:label="lab_srt_ProductOrServiceAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product and Service [Axis] </link:label>
<link:label id="lab_srt_ProductOrServiceAxis_label_en-US" xlink:label="lab_srt_ProductOrServiceAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product and Service [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductOrServiceAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ProductOrServiceAxis" xlink:to="lab_srt_ProductOrServiceAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_Liabilities_c4342065-6b60-42ab-8495-5967e3f85094_totalLabel_en-US" xlink:label="lab_us-gaap_Liabilities" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total liabilities </link:label>
<link:label id="lab_us-gaap_Liabilities_label_en-US" xlink:label="lab_us-gaap_Liabilities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Liabilities"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Liabilities" xlink:to="lab_us-gaap_Liabilities" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_InventoryValuationReservesSalesOfInventory_c7ce929a-6be0-498e-84be-16b5a13277b3_terseLabel_en-US" xlink:label="lab_efoi_InventoryValuationReservesSalesOfInventory" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reduction due to sold inventory </link:label>
<link:label id="lab_efoi_InventoryValuationReservesSalesOfInventory_label_en-US" xlink:label="lab_efoi_InventoryValuationReservesSalesOfInventory" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Valuation Reserves, Sales Of Inventory </link:label>
<link:label id="lab_efoi_InventoryValuationReservesSalesOfInventory_documentation_en-US" xlink:label="lab_efoi_InventoryValuationReservesSalesOfInventory" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Valuation Reserves, Sales Of Inventory </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_InventoryValuationReservesSalesOfInventory" xlink:href="efoi-20201231.xsd#efoi_InventoryValuationReservesSalesOfInventory"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_InventoryValuationReservesSalesOfInventory" xlink:to="lab_efoi_InventoryValuationReservesSalesOfInventory" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_InternationalMember_bc97740a-e724-4609-863d-c9464e49addb_terseLabel_en-US" xlink:label="lab_efoi_InternationalMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> International </link:label>
<link:label id="lab_efoi_InternationalMember_label_en-US" xlink:label="lab_efoi_InternationalMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> International [Member] </link:label>
<link:label id="lab_efoi_InternationalMember_documentation_en-US" xlink:label="lab_efoi_InternationalMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> International </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_InternationalMember" xlink:href="efoi-20201231.xsd#efoi_InternationalMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_InternationalMember" xlink:to="lab_efoi_InternationalMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_9aa05f03-8668-4fcc-83fb-dc10d2468716_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Remaining weighted average life </link:label>
<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_label_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:to="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_28c75203-55ee-4560-83fd-410b397d9900_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expected volatility </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_a25ca24b-e22b-4a5e-9f1e-65ffe24814e7_negatedLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less imputed interest </link:label>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, Undiscounted Excess Amount </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_OperatingLeaseCostNetOfSubleaseIncome_248cca58-f262-46a1-9834-5e6d28c30d8d_totalLabel_en-US" xlink:label="lab_efoi_OperatingLeaseCostNetOfSubleaseIncome" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease cost, net </link:label>
<link:label id="lab_efoi_OperatingLeaseCostNetOfSubleaseIncome_label_en-US" xlink:label="lab_efoi_OperatingLeaseCostNetOfSubleaseIncome" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Cost, Net Of Sublease Income </link:label>
<link:label id="lab_efoi_OperatingLeaseCostNetOfSubleaseIncome_documentation_en-US" xlink:label="lab_efoi_OperatingLeaseCostNetOfSubleaseIncome" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Cost, Net Of Sublease Income </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_OperatingLeaseCostNetOfSubleaseIncome" xlink:href="efoi-20201231.xsd#efoi_OperatingLeaseCostNetOfSubleaseIncome"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_OperatingLeaseCostNetOfSubleaseIncome" xlink:to="lab_efoi_OperatingLeaseCostNetOfSubleaseIncome" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_33799f63-3f76-41ed-820b-355ac896118f_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Related Party Transactions, by Related Party [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Related Party Transactions, by Related Party [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="lab_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_PaycheckProtectionProgramCARESActMember_99e305e0-b920-405e-b849-53a88f1d8632_terseLabel_en-US" xlink:label="lab_efoi_PaycheckProtectionProgramCARESActMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Paycheck Protection Program CARES Act </link:label>
<link:label id="lab_efoi_PaycheckProtectionProgramCARESActMember_label_en-US" xlink:label="lab_efoi_PaycheckProtectionProgramCARESActMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Paycheck Protection Program CARES Act [Member] </link:label>
<link:label id="lab_efoi_PaycheckProtectionProgramCARESActMember_documentation_en-US" xlink:label="lab_efoi_PaycheckProtectionProgramCARESActMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Paycheck Protection Program CARES Act </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_PaycheckProtectionProgramCARESActMember" xlink:href="efoi-20201231.xsd#efoi_PaycheckProtectionProgramCARESActMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_PaycheckProtectionProgramCARESActMember" xlink:to="lab_efoi_PaycheckProtectionProgramCARESActMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LessorOperatingLeaseLiabilityUndiscountedExcessAmount_23049796-8f1f-4cfb-aa6b-5031fce1d123_verboseLabel_en-US" xlink:label="lab_efoi_LessorOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less imputed interest </link:label>
<link:label id="lab_efoi_LessorOperatingLeaseLiabilityUndiscountedExcessAmount_label_en-US" xlink:label="lab_efoi_LessorOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessor, Operating Lease, Liability, Undiscounted Excess Amount </link:label>
<link:label id="lab_efoi_LessorOperatingLeaseLiabilityUndiscountedExcessAmount_documentation_en-US" xlink:label="lab_efoi_LessorOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessor, Operating Lease, Liability, Undiscounted Excess Amount </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LessorOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:href="efoi-20201231.xsd#efoi_LessorOperatingLeaseLiabilityUndiscountedExcessAmount"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LessorOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:to="lab_efoi_LessorOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_d7d6e8b6-e4eb-48c5-bbcf-28c002202134_terseLabel_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitments and Contingencies Disclosure [Abstract] </link:label>
<link:label id="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_label_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitments and Contingencies Disclosure [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:to="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDue_91aecc61-d18e-42ab-9ba5-651ecf9a59b2_totalLabel_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDue" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total future undiscounted lease payments </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDue_label_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDue_documentation_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDue" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDue" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDue"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDue" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncreaseDecreaseInInventories_ca913694-511f-444a-973e-9a335f1d96af_negatedLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInInventories" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventories </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInInventories_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInInventories" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Inventories </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInInventories"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInInventories" xlink:to="lab_us-gaap_IncreaseDecreaseInInventories" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncreaseDecreaseInAccountsPayable_a37efbd7-f0ab-4907-ae6c-5b840185f4d5_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsPayable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts payable </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInAccountsPayable_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsPayable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Accounts Payable </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInAccountsPayable" xlink:to="lab_us-gaap_IncreaseDecreaseInAccountsPayable" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive_b9e9f686-d184-40f9-a3db-ebbff6c0849d_terseLabel_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2025 </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive_label_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due In Rolling Year Five </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive_documentation_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due In Rolling Year Five </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:to="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredOperatingLeaseRightOfUseAsset_2a3f5ba6-000d-4be3-8116-050b2e4c180f_terseLabel_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured lease, right-of-use asset </link:label>
<link:label id="lab_efoi_RestructuredOperatingLeaseRightOfUseAsset_label_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Operating Lease, Right-Of-Use Asset </link:label>
<link:label id="lab_efoi_RestructuredOperatingLeaseRightOfUseAsset_documentation_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Operating Lease, Right-Of-Use Asset </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredOperatingLeaseRightOfUseAsset" xlink:href="efoi-20201231.xsd#efoi_RestructuredOperatingLeaseRightOfUseAsset"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredOperatingLeaseRightOfUseAsset" xlink:to="lab_efoi_RestructuredOperatingLeaseRightOfUseAsset" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtInstrumentAxis_bd041510-a80b-4d87-a373-5b07f18d66f2_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument [Axis] </link:label>
<link:label id="lab_us-gaap_DebtInstrumentAxis_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentAxis" xlink:to="lab_us-gaap_DebtInstrumentAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AdditionalPaidInCapitalMember_6c83ec49-eb56-4ae7-a099-fa5ca797ba89_terseLabel_en-US" xlink:label="lab_us-gaap_AdditionalPaidInCapitalMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additional Paid-in Capital </link:label>
<link:label id="lab_us-gaap_AdditionalPaidInCapitalMember_label_en-US" xlink:label="lab_us-gaap_AdditionalPaidInCapitalMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additional Paid-in Capital [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdditionalPaidInCapitalMember" xlink:to="lab_us-gaap_AdditionalPaidInCapitalMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_A5ElementsEnergyEfficienciesBVILtdMember_9a251828-7f61-4c2f-9fc7-1f3166e39f37_terseLabel_en-US" xlink:label="lab_efoi_A5ElementsEnergyEfficienciesBVILtdMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 5 Elements Energy Efficiencies (BVI) Ltd. </link:label>
<link:label id="lab_efoi_A5ElementsEnergyEfficienciesBVILtdMember_label_en-US" xlink:label="lab_efoi_A5ElementsEnergyEfficienciesBVILtdMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 5 Elements Energy Efficiencies (BVI) Ltd. [Member] </link:label>
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<link:label id="lab_us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock_bdebe870-fe45-4861-9622-294c3084b427_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Quarterly Financial Data </link:label>
<link:label id="lab_us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Quarterly Financial Information [Table Text Block] </link:label>
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<link:label id="lab_us-gaap_ClassOfStockLineItems_050744ba-4030-4f2d-af8f-38ca5640cd28_terseLabel_en-US" xlink:label="lab_us-gaap_ClassOfStockLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Stock [Line Items] </link:label>
<link:label id="lab_us-gaap_ClassOfStockLineItems_label_en-US" xlink:label="lab_us-gaap_ClassOfStockLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Stock [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="lab_us-gaap_ClassOfStockLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncreaseDecreaseInAccruedLiabilities_0ba77167-a4fe-4b6a-a62b-dce8ef2e822d_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued and other liabilities </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInAccruedLiabilities_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Accrued Liabilities </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities"/>
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<link:label id="lab_efoi_LineOfCreditFacilityMonthlyFacilityFee_3bb5ae3a-e064-40d7-9fa3-231de53da36d_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityMonthlyFacilityFee" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Minimum monthly fee </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityMonthlyFacilityFee_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityMonthlyFacilityFee" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Monthly Facility Fee </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityMonthlyFacilityFee_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityMonthlyFacilityFee" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Monthly Facility Fee </link:label>
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<link:label id="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_8694b1a5-7648-4f12-8620-1554d65dba97_terseLabel_en-US" xlink:label="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustments to reconcile net loss to net cash used in operating activities: </link:label>
<link:label id="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_label_en-US" xlink:label="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] </link:label>
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<link:label id="lab_efoi_LEDFLTubularLEDLampsExcludingRedCapsMember_ef4ae58d-ff6a-4e85-a4e0-be6fbd6a0739_terseLabel_en-US" xlink:label="lab_efoi_LEDFLTubularLEDLampsExcludingRedCapsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> LEDFL Tubular LED Lamps (Excluding Red Caps) </link:label>
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<link:label id="lab_efoi_LEDFLTubularLEDLampsExcludingRedCapsMember_documentation_en-US" xlink:label="lab_efoi_LEDFLTubularLEDLampsExcludingRedCapsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> LEDFL Tubular LED Lamps (Excluding Red Caps) [Member] </link:label>
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<link:label id="lab_us-gaap_FinanceLeaseInterestExpense_a426aa80-ca83-4feb-a01f-eadac6eb5eab_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseInterestExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest on lease liabilities </link:label>
<link:label id="lab_us-gaap_FinanceLeaseInterestExpense_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseInterestExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Interest Expense </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseInterestExpense"/>
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<link:label id="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther_b80ef79b-79a4-4210-8228-dd02a0a9642e_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued expenses and other reserves </link:label>
<link:label id="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Other </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther"/>
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<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityUndiscountedExcessAmount_0dd5e5d9-6aca-42bd-8e79-9ed1589428e1_negatedTerseLabel_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less imputed interest </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityUndiscountedExcessAmount_label_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Undiscounted Excess Amount </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityUndiscountedExcessAmount_documentation_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Undiscounted Excess Amount </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
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<link:label id="lab_us-gaap_CommonStockSharesOutstanding_241fe240-4672-4066-b61a-c15fdfaa1f71_verboseLabel_en-US" xlink:label="lab_us-gaap_CommonStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock, number of shares outstanding </link:label>
<link:label id="lab_us-gaap_CommonStockSharesOutstanding_label_en-US" xlink:label="lab_us-gaap_CommonStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Shares, Outstanding </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesOutstanding"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockSharesOutstanding" xlink:to="lab_us-gaap_CommonStockSharesOutstanding" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncomeTaxDisclosureAbstract_d7165c95-dd6d-4860-89b6-1a74b6c9a1d1_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Disclosure [Abstract] </link:label>
<link:label id="lab_us-gaap_IncomeTaxDisclosureAbstract_label_en-US" xlink:label="lab_us-gaap_IncomeTaxDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Disclosure [Abstract] </link:label>
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<link:label id="lab_us-gaap_RevolvingCreditFacilityMember_b07c277f-454d-422f-a210-e470d45df831_terseLabel_en-US" xlink:label="lab_us-gaap_RevolvingCreditFacilityMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revolving Credit Facility </link:label>
<link:label id="lab_us-gaap_RevolvingCreditFacilityMember_label_en-US" xlink:label="lab_us-gaap_RevolvingCreditFacilityMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revolving Credit Facility [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
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<link:label id="lab_us-gaap_OtherCurrentAssetsTextBlock_73592f95-0899-4857-a989-755241ce75ff_terseLabel_en-US" xlink:label="lab_us-gaap_OtherCurrentAssetsTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid and Other Current Assets </link:label>
<link:label id="lab_us-gaap_OtherCurrentAssetsTextBlock_label_en-US" xlink:label="lab_us-gaap_OtherCurrentAssetsTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Current Assets [Text Block] </link:label>
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<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_721a8e16-b416-44d7-8139-cf994ef325a3_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of Shares Exercisable (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Exercise Price Range, Shares Exercisable </link:label>
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<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_b6389ffa-b3bc-4a2d-80c9-507bc6871ddf_totalLabel_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss from operations before income taxes </link:label>
<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_label_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest </link:label>
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<link:label id="lab_us-gaap_ResearchAndDevelopmentExpense_80c545e4-3b64-4026-80d7-5d263506dcf6_terseLabel_en-US" xlink:label="lab_us-gaap_ResearchAndDevelopmentExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product development </link:label>
<link:label id="lab_us-gaap_ResearchAndDevelopmentExpense_label_en-US" xlink:label="lab_us-gaap_ResearchAndDevelopmentExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Research and Development Expense </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ResearchAndDevelopmentExpense" xlink:to="lab_us-gaap_ResearchAndDevelopmentExpense" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants_70b034b8-f854-4acc-996c-f086525c4cb8_terseLabel_en-US" xlink:label="lab_us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Issuance of common stock upon the exercise of warrants </link:label>
<link:label id="lab_us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants_label_en-US" xlink:label="lab_us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants" xlink:to="lab_us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_87fdbec8-2be1-4903-bdaf-f2215153c91b_terseLabel_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other </link:label>
<link:label id="lab_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_label_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Other Adjustments, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SubsequentEventMember_4ad45342-86ed-4cf1-8880-e7474ed3f73e_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event </link:label>
<link:label id="lab_us-gaap_SubsequentEventMember_label_en-US" xlink:label="lab_us-gaap_SubsequentEventMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventMember" xlink:to="lab_us-gaap_SubsequentEventMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_bdc65c21-eae2-4c70-b821-4e50261e48ae_periodStartLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Outstanding at beginning of period (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_e29c2378-04d1-4016-bd4c-b3f3641cfa1a_periodEndLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Outstanding at end of period (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DomesticCountryMember_f647d1d2-0562-45dc-9e41-25214f760e55_terseLabel_en-US" xlink:label="lab_us-gaap_DomesticCountryMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> U.S. Federal </link:label>
<link:label id="lab_us-gaap_DomesticCountryMember_label_en-US" xlink:label="lab_us-gaap_DomesticCountryMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Domestic Tax Authority [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DomesticCountryMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DomesticCountryMember" xlink:to="lab_us-gaap_DomesticCountryMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CommonStockSharesAuthorized_0e39a931-4e19-4ce4-8184-bfc17555d824_verboseLabel_en-US" xlink:label="lab_us-gaap_CommonStockSharesAuthorized" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock, number of shares authorized </link:label>
<link:label id="lab_us-gaap_CommonStockSharesAuthorized_045a4814-8380-48b0-b6f6-93414d0b0f00_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockSharesAuthorized" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Shares Authorized </link:label>
<link:label id="lab_us-gaap_CommonStockSharesAuthorized_label_en-US" xlink:label="lab_us-gaap_CommonStockSharesAuthorized" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Shares Authorized </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesAuthorized"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockSharesAuthorized" xlink:to="lab_us-gaap_CommonStockSharesAuthorized" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ConcentrationRiskByTypeAxis_a14edd66-5e79-4faf-b462-de9df2b24826_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskByTypeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Type [Axis] </link:label>
<link:label id="lab_us-gaap_ConcentrationRiskByTypeAxis_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskByTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Type [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis" xlink:to="lab_us-gaap_ConcentrationRiskByTypeAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentGross_13309c53-258d-4678-bb0b-64c6e21aaa23_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentGross" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment at cost </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentGross_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentGross" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment, Gross </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentGross" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentGross" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProceedsFromStockOptionsExercised_8dd19bbf-edaf-4f5a-b196-238d874fa406_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromStockOptionsExercised" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from exercise of stock options and purchases through employee stock purchase plan </link:label>
<link:label id="lab_us-gaap_ProceedsFromStockOptionsExercised_label_en-US" xlink:label="lab_us-gaap_ProceedsFromStockOptionsExercised" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Stock Options Exercised </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromStockOptionsExercised" xlink:to="lab_us-gaap_ProceedsFromStockOptionsExercised" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_34c2e7e6-a3fb-42b5-8f7c-f73630548387_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> U.S. Federal </link:label>
<link:label id="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Federal Income Tax Expense (Benefit) </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringPlanDomain_28a4424b-6484-4ddd-a9f1-eafbb0ac8f8a_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringPlanDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Plan [Domain] </link:label>
<link:label id="lab_us-gaap_RestructuringPlanDomain_label_en-US" xlink:label="lab_us-gaap_RestructuringPlanDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Plan [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringPlanDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringPlanDomain" xlink:to="lab_us-gaap_RestructuringPlanDomain" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ExercisePriceRangeFourMember_c9af7692-ad67-4648-85d4-bf5edebe1b04_terseLabel_en-US" xlink:label="lab_efoi_ExercisePriceRangeFourMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise price, range four </link:label>
<link:label id="lab_efoi_ExercisePriceRangeFourMember_label_en-US" xlink:label="lab_efoi_ExercisePriceRangeFourMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise Price Range Four [Member] </link:label>
<link:label id="lab_efoi_ExercisePriceRangeFourMember_documentation_en-US" xlink:label="lab_efoi_ExercisePriceRangeFourMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> The third exercise price range. </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ExercisePriceRangeFourMember" xlink:href="efoi-20201231.xsd#efoi_ExercisePriceRangeFourMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ExercisePriceRangeFourMember" xlink:to="lab_efoi_ExercisePriceRangeFourMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ValuationAllowancesAndReservesTypeAxis_719d359b-3b04-42fc-a2b9-2d917c6c0106_terseLabel_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] </link:label>
<link:label id="lab_us-gaap_ValuationAllowancesAndReservesTypeAxis_label_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:to="lab_us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LonglivedAssetsLocatedinUSPercent_f1c37df0-b6d1-4fb9-8667-318846859434_terseLabel_en-US" xlink:label="lab_efoi_LonglivedAssetsLocatedinUSPercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-lived assets located in US, percent </link:label>
<link:label id="lab_efoi_LonglivedAssetsLocatedinUSPercent_label_en-US" xlink:label="lab_efoi_LonglivedAssetsLocatedinUSPercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-lived Assets Located in US, Percent </link:label>
<link:label id="lab_efoi_LonglivedAssetsLocatedinUSPercent_documentation_en-US" xlink:label="lab_efoi_LonglivedAssetsLocatedinUSPercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-lived Assets Located in US, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LonglivedAssetsLocatedinUSPercent" xlink:href="efoi-20201231.xsd#efoi_LonglivedAssetsLocatedinUSPercent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LonglivedAssetsLocatedinUSPercent" xlink:to="lab_efoi_LonglivedAssetsLocatedinUSPercent" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredOperatingLeaseLiability_fc406700-de02-4c69-adf5-3ab2c1065f26_terseLabel_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured lease liabilities </link:label>
<link:label id="lab_efoi_RestructuredOperatingLeaseLiability_8fed63e8-cd7f-4e2f-aefb-ffe831319ad5_verboseLabel_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total lease obligations </link:label>
<link:label id="lab_efoi_RestructuredOperatingLeaseLiability_label_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Operating Lease, Liability </link:label>
<link:label id="lab_efoi_RestructuredOperatingLeaseLiability_documentation_en-US" xlink:label="lab_efoi_RestructuredOperatingLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Operating Lease, Liability </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredOperatingLeaseLiability" xlink:href="efoi-20201231.xsd#efoi_RestructuredOperatingLeaseLiability"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredOperatingLeaseLiability" xlink:to="lab_efoi_RestructuredOperatingLeaseLiability" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncomeStatementAbstract_81e842a3-5c31-4309-8a96-e15ce1e6c2c4_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeStatementAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Statement [Abstract] </link:label>
<link:label id="lab_us-gaap_IncomeStatementAbstract_label_en-US" xlink:label="lab_us-gaap_IncomeStatementAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Statement [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeStatementAbstract" xlink:to="lab_us-gaap_IncomeStatementAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeMember_06e4b403-f215-4e56-a39c-11316dc625f2_terseLabel_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated Other Comprehensive Loss </link:label>
<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeMember_label_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> AOCI Attributable to Parent [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:to="lab_us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingLeaseLiabilityNoncurrent_28038925-7adf-499c-b939-8088d2ef22c4_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease liabilities, net of current portion </link:label>
<link:label id="lab_us-gaap_OperatingLeaseLiabilityNoncurrent_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Liability, Noncurrent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:to="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_9c96835e-aaf0-4e0f-bac6-2f6845fd1980_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid and other assets </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Prepaid Expense and Other Assets </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:to="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StandardProductWarrantyAccrualWarrantiesIssued_9df9afef-7453-48dd-bdec-f144d382aa2b_terseLabel_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyAccrualWarrantiesIssued" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accruals for warranties issued </link:label>
<link:label id="lab_us-gaap_StandardProductWarrantyAccrualWarrantiesIssued_label_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyAccrualWarrantiesIssued" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Standard Product Warranty Accrual, Increase for Warranties Issued </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrualWarrantiesIssued" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StandardProductWarrantyAccrualWarrantiesIssued"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StandardProductWarrantyAccrualWarrantiesIssued" xlink:to="lab_us-gaap_StandardProductWarrantyAccrualWarrantiesIssued" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_GovernmentProductsMember_0ed6b78c-32d1-41fb-a425-4c4cd08388f2_terseLabel_en-US" xlink:label="lab_efoi_GovernmentProductsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> MMM products </link:label>
<link:label id="lab_efoi_GovernmentProductsMember_label_en-US" xlink:label="lab_efoi_GovernmentProductsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Government Products [Member] </link:label>
<link:label id="lab_efoi_GovernmentProductsMember_documentation_en-US" xlink:label="lab_efoi_GovernmentProductsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Government Products segment. </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_GovernmentProductsMember" xlink:href="efoi-20201231.xsd#efoi_GovernmentProductsMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_GovernmentProductsMember" xlink:to="lab_efoi_GovernmentProductsMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_71dfcf8b-f6ea-4971-a212-aef3e44a31a0_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unamortized discount (premium) and issuance costs </link:label>
<link:label id="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:to="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_UseOfEstimates_271c1192-da7e-4cdd-ba11-1b734b465812_terseLabel_en-US" xlink:label="lab_us-gaap_UseOfEstimates" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Use of estimates </link:label>
<link:label id="lab_us-gaap_UseOfEstimates_label_en-US" xlink:label="lab_us-gaap_UseOfEstimates" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Use of Estimates, Policy [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UseOfEstimates" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UseOfEstimates"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UseOfEstimates" xlink:to="lab_us-gaap_UseOfEstimates" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt_7376e784-873f-48d3-aaaf-998dabba4a4f_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from issuance of subordinated convertible promissory notes </link:label>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt_label_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Issuance of Subordinated Long-term Debt </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt" xlink:to="lab_us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AssetsCurrentAbstract_0d47f9ee-a723-410e-8889-033f81275ce1_terseLabel_en-US" xlink:label="lab_us-gaap_AssetsCurrentAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current assets: </link:label>
<link:label id="lab_us-gaap_AssetsCurrentAbstract_label_en-US" xlink:label="lab_us-gaap_AssetsCurrentAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets, Current [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrentAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsCurrentAbstract" xlink:to="lab_us-gaap_AssetsCurrentAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncomeTaxAuthorityDomain_c3bc5c70-2fda-44df-a2e3-758aac4cc347_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Authority [Domain] </link:label>
<link:label id="lab_us-gaap_IncomeTaxAuthorityDomain_label_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Authority [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:to="lab_us-gaap_IncomeTaxAuthorityDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_76a8c12d-974b-4ef5-8cca-8deeb09261bf_terseLabel_en-US" xlink:label="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Computer software </link:label>
<link:label id="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_label_en-US" xlink:label="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Software and Software Development Costs [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:to="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuringReserveAccretion_e68dc821-aa2f-4a88-b276-5ef919bd335e_terseLabel_en-US" xlink:label="lab_efoi_RestructuringReserveAccretion" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accretion of lease obligations </link:label>
<link:label id="lab_efoi_RestructuringReserveAccretion_label_en-US" xlink:label="lab_efoi_RestructuringReserveAccretion" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Reserve, Accretion </link:label>
<link:label id="lab_efoi_RestructuringReserveAccretion_documentation_en-US" xlink:label="lab_efoi_RestructuringReserveAccretion" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Reserve, Accretion </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuringReserveAccretion" xlink:href="efoi-20201231.xsd#efoi_RestructuringReserveAccretion"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuringReserveAccretion" xlink:to="lab_efoi_RestructuringReserveAccretion" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ComprehensiveIncomeNetOfTax_59b7fb2b-c564-46ec-80b3-01b25f0924d5_totalLabel_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomeNetOfTax" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Comprehensive loss </link:label>
<link:label id="lab_us-gaap_ComprehensiveIncomeNetOfTax_label_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomeNetOfTax" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Comprehensive Income (Loss), Net of Tax, Attributable to Parent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax" xlink:to="lab_us-gaap_ComprehensiveIncomeNetOfTax" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_cde94206-fe75-4966-84b7-d148a7077f28_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Dividend yield </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PreferredStockParOrStatedValuePerShare_b2feb165-28f7-443b-af88-a4aff11ac874_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockParOrStatedValuePerShare" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred stock, par value (in dollars per share) </link:label>
<link:label id="lab_us-gaap_PreferredStockParOrStatedValuePerShare_label_en-US" xlink:label="lab_us-gaap_PreferredStockParOrStatedValuePerShare" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred Stock, Par or Stated Value Per Share </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredStockParOrStatedValuePerShare" xlink:to="lab_us-gaap_PreferredStockParOrStatedValuePerShare" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ClassOfWarrantOrRightWarrantsIssued_461373de-9e15-4f3e-a569-f7018a4f617d_terseLabel_en-US" xlink:label="lab_efoi_ClassOfWarrantOrRightWarrantsIssued" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of warrants issued (in shares) </link:label>
<link:label id="lab_efoi_ClassOfWarrantOrRightWarrantsIssued_label_en-US" xlink:label="lab_efoi_ClassOfWarrantOrRightWarrantsIssued" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class Of Warrant Or Right, Warrants Issued </link:label>
<link:label id="lab_efoi_ClassOfWarrantOrRightWarrantsIssued_documentation_en-US" xlink:label="lab_efoi_ClassOfWarrantOrRightWarrantsIssued" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class Of Warrant Or Right, Warrants Issued </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ClassOfWarrantOrRightWarrantsIssued" xlink:href="efoi-20201231.xsd#efoi_ClassOfWarrantOrRightWarrantsIssued"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ClassOfWarrantOrRightWarrantsIssued" xlink:to="lab_efoi_ClassOfWarrantOrRightWarrantsIssued" xlink:type="arc" order="1"/>
<link:label id="lab_dei_DocumentsIncorporatedByReferenceTextBlock_388edfa0-7bbe-4cfc-a4f4-2fceb5b28c7c_terseLabel_en-US" xlink:label="lab_dei_DocumentsIncorporatedByReferenceTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Documents Incorporated by Reference </link:label>
<link:label id="lab_dei_DocumentsIncorporatedByReferenceTextBlock_label_en-US" xlink:label="lab_dei_DocumentsIncorporatedByReferenceTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Documents Incorporated by Reference [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentsIncorporatedByReferenceTextBlock" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentsIncorporatedByReferenceTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentsIncorporatedByReferenceTextBlock" xlink:to="lab_dei_DocumentsIncorporatedByReferenceTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_b6754a90-6d58-4b03-bdf0-152bde524c91_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Effective Income Tax Rate Reconciliation </link:label>
<link:label id="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DebtInstrumentInterestRateStatedPercentageCollateralManagementFee_685ec150-36aa-492c-9b88-2c72907bd1da_terseLabel_en-US" xlink:label="lab_efoi_DebtInstrumentInterestRateStatedPercentageCollateralManagementFee" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stated interest rate on collateral management fee </link:label>
<link:label id="lab_efoi_DebtInstrumentInterestRateStatedPercentageCollateralManagementFee_label_en-US" xlink:label="lab_efoi_DebtInstrumentInterestRateStatedPercentageCollateralManagementFee" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Interest Rate, Stated Percentage, Collateral Management Fee </link:label>
<link:label id="lab_efoi_DebtInstrumentInterestRateStatedPercentageCollateralManagementFee_documentation_en-US" xlink:label="lab_efoi_DebtInstrumentInterestRateStatedPercentageCollateralManagementFee" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Interest Rate, Stated Percentage, Collateral Management Fee </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DebtInstrumentInterestRateStatedPercentageCollateralManagementFee" xlink:href="efoi-20201231.xsd#efoi_DebtInstrumentInterestRateStatedPercentageCollateralManagementFee"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DebtInstrumentInterestRateStatedPercentageCollateralManagementFee" xlink:to="lab_efoi_DebtInstrumentInterestRateStatedPercentageCollateralManagementFee" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringReserveRollForward_e9c92484-cd16-482e-b649-c7eef6e419e6_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringReserveRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Reserve [Roll Forward] </link:label>
<link:label id="lab_us-gaap_RestructuringReserveRollForward_label_en-US" xlink:label="lab_us-gaap_RestructuringReserveRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Reserve [Roll Forward] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveRollForward" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringReserveRollForward"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringReserveRollForward" xlink:to="lab_us-gaap_RestructuringReserveRollForward" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ValuationAllowancesAndReservesDeductions_f126f7d8-b30d-4f95-b5c9-0c6f81477904_terseLabel_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesDeductions" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deductions </link:label>
<link:label id="lab_us-gaap_ValuationAllowancesAndReservesDeductions_label_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesDeductions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDeductions" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDeductions"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDeductions" xlink:to="lab_us-gaap_ValuationAllowancesAndReservesDeductions" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DebtInstrumentPeriodDomain_3d2933d7-2589-463f-89cf-7784ce11cfa7_terseLabel_en-US" xlink:label="lab_efoi_DebtInstrumentPeriodDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Period [Domain] </link:label>
<link:label id="lab_efoi_DebtInstrumentPeriodDomain_label_en-US" xlink:label="lab_efoi_DebtInstrumentPeriodDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Period [Domain] </link:label>
<link:label id="lab_efoi_DebtInstrumentPeriodDomain_documentation_en-US" xlink:label="lab_efoi_DebtInstrumentPeriodDomain" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> [Domain] for Debt Instrument, Period [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DebtInstrumentPeriodDomain" xlink:href="efoi-20201231.xsd#efoi_DebtInstrumentPeriodDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DebtInstrumentPeriodDomain" xlink:to="lab_efoi_DebtInstrumentPeriodDomain" xlink:type="arc" order="1"/>
<link:label id="lab_srt_ScenarioUnspecifiedDomain_4a231a34-bbc2-4816-8ba6-ba0ce44e1829_terseLabel_en-US" xlink:label="lab_srt_ScenarioUnspecifiedDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Scenario [Domain] </link:label>
<link:label id="lab_srt_ScenarioUnspecifiedDomain_label_en-US" xlink:label="lab_srt_ScenarioUnspecifiedDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Scenario [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ScenarioUnspecifiedDomain" xlink:to="lab_srt_ScenarioUnspecifiedDomain" xlink:type="arc" order="1"/>
<link:label id="lab_dei_LegalEntityAxis_f63827af-863c-4870-a5fc-98946d002cca_terseLabel_en-US" xlink:label="lab_dei_LegalEntityAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Legal Entity [Axis] </link:label>
<link:label id="lab_dei_LegalEntityAxis_label_en-US" xlink:label="lab_dei_LegalEntityAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Legal Entity [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_LegalEntityAxis" xlink:to="lab_dei_LegalEntityAxis" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ContractWithCustomerPaymentTerms_318e5a00-48ef-4514-bed5-88aecaf5316b_terseLabel_en-US" xlink:label="lab_efoi_ContractWithCustomerPaymentTerms" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payment terms </link:label>
<link:label id="lab_efoi_ContractWithCustomerPaymentTerms_label_en-US" xlink:label="lab_efoi_ContractWithCustomerPaymentTerms" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Payment Terms </link:label>
<link:label id="lab_efoi_ContractWithCustomerPaymentTerms_documentation_en-US" xlink:label="lab_efoi_ContractWithCustomerPaymentTerms" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Payment Terms </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ContractWithCustomerPaymentTerms" xlink:href="efoi-20201231.xsd#efoi_ContractWithCustomerPaymentTerms"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ContractWithCustomerPaymentTerms" xlink:to="lab_efoi_ContractWithCustomerPaymentTerms" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_3bca075a-445e-4975-9b34-6a8bf170e30c_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions of property and equipment </link:label>
<link:label id="lab_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_label_en-US" xlink:label="lab_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments to Acquire Property, Plant, and Equipment </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:to="lab_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:type="arc" order="1"/>
<link:label id="lab_dei_CityAreaCode_13f9a9a0-0f8b-4d57-a941-83744af68268_terseLabel_en-US" xlink:label="lab_dei_CityAreaCode" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> City Area Code </link:label>
<link:label id="lab_dei_CityAreaCode_label_en-US" xlink:label="lab_dei_CityAreaCode" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> City Area Code </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_CityAreaCode"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_CityAreaCode" xlink:to="lab_dei_CityAreaCode" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths_e900dffc-dbec-48c4-aca5-630e398e074d_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2021 </link:label>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths_label_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessor, Operating Lease, Payments to be Received, Next Rolling Twelve Months </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths" xlink:to="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncomeTaxAuthorityAxis_4449b0b4-e729-4189-ae87-3d59cffaf2e0_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Authority [Axis] </link:label>
<link:label id="lab_us-gaap_IncomeTaxAuthorityAxis_label_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Authority [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:to="lab_us-gaap_IncomeTaxAuthorityAxis" xlink:type="arc" order="1"/>
<link:label id="lab_dei_DocumentPeriodEndDate_4bd109a7-023b-4aa6-99f3-fe104ecf694d_terseLabel_en-US" xlink:label="lab_dei_DocumentPeriodEndDate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Period End Date </link:label>
<link:label id="lab_dei_DocumentPeriodEndDate_label_en-US" xlink:label="lab_dei_DocumentPeriodEndDate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Period End Date </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentPeriodEndDate"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentPeriodEndDate" xlink:to="lab_dei_DocumentPeriodEndDate" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_A5ElementsGlobalAdvisorsMember_6d83f897-b4f7-4f02-92c2-7e8019e06401_terseLabel_en-US" xlink:label="lab_efoi_A5ElementsGlobalAdvisorsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 5 Elements Global Advisors </link:label>
<link:label id="lab_efoi_A5ElementsGlobalAdvisorsMember_label_en-US" xlink:label="lab_efoi_A5ElementsGlobalAdvisorsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 5 Elements Global Advisors [Member] </link:label>
<link:label id="lab_efoi_A5ElementsGlobalAdvisorsMember_documentation_en-US" xlink:label="lab_efoi_A5ElementsGlobalAdvisorsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 5 Elements Global Advisors [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_A5ElementsGlobalAdvisorsMember" xlink:href="efoi-20201231.xsd#efoi_A5ElementsGlobalAdvisorsMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_A5ElementsGlobalAdvisorsMember" xlink:to="lab_efoi_A5ElementsGlobalAdvisorsMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAbstract_9f5b1184-0dfe-4f50-b956-1a8da37eabd8_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Abstract] </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAbstract_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFive_c0ac8f29-083e-4052-b1a1-3cbe3ab6d0f3_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFive" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2025 </link:label>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFive_label_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessor, Operating Lease, Payments to be Received, Rolling Year Five </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFive" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFive"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFive" xlink:to="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFive" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_MovementInStandardProductWarrantyAccrualRollForward_b0a6fc17-d0aa-44b3-8582-439069a3f4da_terseLabel_en-US" xlink:label="lab_us-gaap_MovementInStandardProductWarrantyAccrualRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Movement in Standard Product Warranty Accrual [Roll Forward] </link:label>
<link:label id="lab_us-gaap_MovementInStandardProductWarrantyAccrualRollForward_label_en-US" xlink:label="lab_us-gaap_MovementInStandardProductWarrantyAccrualRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Movement in Standard Product Warranty Accrual [Roll Forward] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MovementInStandardProductWarrantyAccrualRollForward" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MovementInStandardProductWarrantyAccrualRollForward"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MovementInStandardProductWarrantyAccrualRollForward" xlink:to="lab_us-gaap_MovementInStandardProductWarrantyAccrualRollForward" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DebtInstrumentPeriodAxis_d9443635-1107-4921-bebe-ef234fa39517_terseLabel_en-US" xlink:label="lab_efoi_DebtInstrumentPeriodAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Period [Axis] </link:label>
<link:label id="lab_efoi_DebtInstrumentPeriodAxis_label_en-US" xlink:label="lab_efoi_DebtInstrumentPeriodAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Period [Axis] </link:label>
<link:label id="lab_efoi_DebtInstrumentPeriodAxis_documentation_en-US" xlink:label="lab_efoi_DebtInstrumentPeriodAxis" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Period [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DebtInstrumentPeriodAxis" xlink:href="efoi-20201231.xsd#efoi_DebtInstrumentPeriodAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DebtInstrumentPeriodAxis" xlink:to="lab_efoi_DebtInstrumentPeriodAxis" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_A13DGroupMember_be69ae89-1b9f-4b9b-a9d9-c95c766846df_terseLabel_en-US" xlink:label="lab_efoi_A13DGroupMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 13D Group </link:label>
<link:label id="lab_efoi_A13DGroupMember_label_en-US" xlink:label="lab_efoi_A13DGroupMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 13D Group [Member] </link:label>
<link:label id="lab_efoi_A13DGroupMember_documentation_en-US" xlink:label="lab_efoi_A13DGroupMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 13D Group [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_A13DGroupMember" xlink:href="efoi-20201231.xsd#efoi_A13DGroupMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_A13DGroupMember" xlink:to="lab_efoi_A13DGroupMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingLossCarryforwardsTable_282ad3bd-c288-466b-a2e1-a62828c0ead4_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLossCarryforwardsTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Loss Carryforwards [Table] </link:label>
<link:label id="lab_us-gaap_OperatingLossCarryforwardsTable_label_en-US" xlink:label="lab_us-gaap_OperatingLossCarryforwardsTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Loss Carryforwards [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable" xlink:to="lab_us-gaap_OperatingLossCarryforwardsTable" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_FinanceLeaseRightOfUseAssetGross_268be829-7448-4986-ae05-577b00d14bbe_terseLabel_en-US" xlink:label="lab_efoi_FinanceLeaseRightOfUseAssetGross" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment </link:label>
<link:label id="lab_efoi_FinanceLeaseRightOfUseAssetGross_label_en-US" xlink:label="lab_efoi_FinanceLeaseRightOfUseAssetGross" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-Of-Use Asset, Gross </link:label>
<link:label id="lab_efoi_FinanceLeaseRightOfUseAssetGross_documentation_en-US" xlink:label="lab_efoi_FinanceLeaseRightOfUseAssetGross" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-Of-Use Asset, Gross </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_FinanceLeaseRightOfUseAssetGross" xlink:href="efoi-20201231.xsd#efoi_FinanceLeaseRightOfUseAssetGross"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_FinanceLeaseRightOfUseAssetGross" xlink:to="lab_efoi_FinanceLeaseRightOfUseAssetGross" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive_8acf79f0-9a2f-4796-a9d9-0007a55f94a4_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2025 </link:label>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Five </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingLeaseImpairmentLoss_4c2c4e25-8da0-4dea-9228-669e090ac59b_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseImpairmentLoss" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease, impairment loss </link:label>
<link:label id="lab_us-gaap_OperatingLeaseImpairmentLoss_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseImpairmentLoss" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Impairment Loss </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseImpairmentLoss" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseImpairmentLoss"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseImpairmentLoss" xlink:to="lab_us-gaap_OperatingLeaseImpairmentLoss" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_QuarterlyFinancialInformationDisclosureAbstract_cb72f596-04b8-4320-9642-f24de8526713_terseLabel_en-US" xlink:label="lab_us-gaap_QuarterlyFinancialInformationDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Quarterly Financial Information Disclosure [Abstract] </link:label>
<link:label id="lab_us-gaap_QuarterlyFinancialInformationDisclosureAbstract_label_en-US" xlink:label="lab_us-gaap_QuarterlyFinancialInformationDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Quarterly Financial Information Disclosure [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_QuarterlyFinancialInformationDisclosureAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_QuarterlyFinancialInformationDisclosureAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_QuarterlyFinancialInformationDisclosureAbstract" xlink:to="lab_us-gaap_QuarterlyFinancialInformationDisclosureAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfInventoryCurrentTableTextBlock_7b513b56-400e-42bb-b30d-145a7cc2cf73_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Inventory </link:label>
<link:label id="lab_us-gaap_ScheduleOfInventoryCurrentTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Inventory, Current [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfInventoryCurrentTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LongtermDebtTypeDomain_709e7507-9c80-408a-8d78-da5b37eabb60_terseLabel_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term Debt, Type [Domain] </link:label>
<link:label id="lab_us-gaap_LongtermDebtTypeDomain_label_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term Debt, Type [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongtermDebtTypeDomain" xlink:to="lab_us-gaap_LongtermDebtTypeDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensation_76ade08e-f17f-4c76-871d-5dbaa37533d6_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock-based compensation </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensation_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Noncash Expense </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensation"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensation" xlink:to="lab_us-gaap_ShareBasedCompensation" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccountsPayableMember_9dc1351d-a741-48b1-9dd3-811437de3d20_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsPayableMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Payable </link:label>
<link:label id="lab_us-gaap_AccountsPayableMember_label_en-US" xlink:label="lab_us-gaap_AccountsPayableMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Payable [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsPayableMember" xlink:to="lab_us-gaap_AccountsPayableMember" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityDomain_03d98691-537a-42cd-ac6c-702388781793_terseLabel_en-US" xlink:label="lab_dei_EntityDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity [Domain] </link:label>
<link:label id="lab_dei_EntityDomain_label_en-US" xlink:label="lab_dei_EntityDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityDomain" xlink:to="lab_dei_EntityDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringReserveNoncurrent_7c4bf7fd-62be-4035-8cba-4a8af93226ce_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringReserveNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term restructuring liability, included in other liabilities </link:label>
<link:label id="lab_us-gaap_RestructuringReserveNoncurrent_label_en-US" xlink:label="lab_us-gaap_RestructuringReserveNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Reserve, Noncurrent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveNoncurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringReserveNoncurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringReserveNoncurrent" xlink:to="lab_us-gaap_RestructuringReserveNoncurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_0d742a93-9088-4e05-8c69-13cc07924b9c_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock withheld in lieu of income tax withholding on vesting of restricted stock units </link:label>
<link:label id="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_label_en-US" xlink:label="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payment, Tax Withholding, Share-based Payment Arrangement </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:to="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:type="arc" order="1"/>
<link:label id="lab_dei_CoverAbstract_label_en-US" xlink:label="lab_dei_CoverAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cover [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_CoverAbstract" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_CoverAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_CoverAbstract" xlink:to="lab_dei_CoverAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_QuarterlyFinancialInformationTextBlock_f19fa79d-29e0-4006-b9b5-6cb20518cc1d_terseLabel_en-US" xlink:label="lab_us-gaap_QuarterlyFinancialInformationTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Supplementary Financial Information to Item 8. </link:label>
<link:label id="lab_us-gaap_QuarterlyFinancialInformationTextBlock_label_en-US" xlink:label="lab_us-gaap_QuarterlyFinancialInformationTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Quarterly Financial Information [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_QuarterlyFinancialInformationTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_QuarterlyFinancialInformationTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_QuarterlyFinancialInformationTextBlock" xlink:to="lab_us-gaap_QuarterlyFinancialInformationTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_12d69eb1-d681-40b6-91c1-7a3a9f914683_terseLabel_en-US" xlink:label="lab_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] </link:label>
<link:label id="lab_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_label_en-US" xlink:label="lab_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" xlink:to="lab_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringReserveAccrualAdjustment1_91f16b8b-41e8-449b-91d4-bbf19fec4cf8_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringReserveAccrualAdjustment1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustment of lease obligations </link:label>
<link:label id="lab_us-gaap_RestructuringReserveAccrualAdjustment1_1a0e5460-83fc-481e-8036-8774a698f8d6_verboseLabel_en-US" xlink:label="lab_us-gaap_RestructuringReserveAccrualAdjustment1" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reclassification upon adoption of Topic 842 </link:label>
<link:label id="lab_us-gaap_RestructuringReserveAccrualAdjustment1_label_en-US" xlink:label="lab_us-gaap_RestructuringReserveAccrualAdjustment1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Reserve, Accrual Adjustment </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveAccrualAdjustment1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringReserveAccrualAdjustment1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringReserveAccrualAdjustment1" xlink:to="lab_us-gaap_RestructuringReserveAccrualAdjustment1" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ProceedsFromPaycheckProtectionProgram_7bddce11-7637-4245-85d9-8e6bdd5c75b2_terseLabel_en-US" xlink:label="lab_efoi_ProceedsFromPaycheckProtectionProgram" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from PPP loan </link:label>
<link:label id="lab_efoi_ProceedsFromPaycheckProtectionProgram_label_en-US" xlink:label="lab_efoi_ProceedsFromPaycheckProtectionProgram" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds From Paycheck Protection Program </link:label>
<link:label id="lab_efoi_ProceedsFromPaycheckProtectionProgram_documentation_en-US" xlink:label="lab_efoi_ProceedsFromPaycheckProtectionProgram" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds From Paycheck Protection Program </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ProceedsFromPaycheckProtectionProgram" xlink:href="efoi-20201231.xsd#efoi_ProceedsFromPaycheckProtectionProgram"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ProceedsFromPaycheckProtectionProgram" xlink:to="lab_efoi_ProceedsFromPaycheckProtectionProgram" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_5eb5ef08-7cfe-43e1-befa-44a49c916217_verboseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment, useful life </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment, Useful Life </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeLeaseDescriptionLineItems_041a980c-301b-4a47-8d1c-e313c68d5528_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeLeaseDescriptionLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Lease, Description [Line Items] </link:label>
<link:label id="lab_us-gaap_LesseeLeaseDescriptionLineItems_label_en-US" xlink:label="lab_us-gaap_LesseeLeaseDescriptionLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Lease, Description [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="lab_us-gaap_LesseeLeaseDescriptionLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeOperatingLeasesTextBlock_1c087e02-6784-48fc-af34-a361c2beb0af_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeasesTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leases </link:label>
<link:label id="lab_us-gaap_LesseeOperatingLeasesTextBlock_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeasesTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Leases [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeasesTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeasesTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeasesTextBlock" xlink:to="lab_us-gaap_LesseeOperatingLeasesTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearThree_42dd3830-2455-4f03-ac2e-39ebc6f0b134_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearThree" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2023 </link:label>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearThree_label_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearThree" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessor, Operating Lease, Payments to be Received, Rolling Year Three </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearThree" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearThree"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearThree" xlink:to="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearThree" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_PaymentProtectionProgramNoncurrent_aaf3dd2f-7073-4701-836d-a263fcdbe89d_terseLabel_en-US" xlink:label="lab_efoi_PaymentProtectionProgramNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> PPP loan, net of current maturities </link:label>
<link:label id="lab_efoi_PaymentProtectionProgramNoncurrent_label_en-US" xlink:label="lab_efoi_PaymentProtectionProgramNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payment Protection Program, Noncurrent </link:label>
<link:label id="lab_efoi_PaymentProtectionProgramNoncurrent_documentation_en-US" xlink:label="lab_efoi_PaymentProtectionProgramNoncurrent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payment Protection Program, Noncurrent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_PaymentProtectionProgramNoncurrent" xlink:href="efoi-20201231.xsd#efoi_PaymentProtectionProgramNoncurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_PaymentProtectionProgramNoncurrent" xlink:to="lab_efoi_PaymentProtectionProgramNoncurrent" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DebtInstrumentProceedsToBePaidToLenderPercent_0d33eac6-bdab-4344-aebe-9f748d7fb0be_terseLabel_en-US" xlink:label="lab_efoi_DebtInstrumentProceedsToBePaidToLenderPercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percent proceeds to be paid to Lender </link:label>
<link:label id="lab_efoi_DebtInstrumentProceedsToBePaidToLenderPercent_label_en-US" xlink:label="lab_efoi_DebtInstrumentProceedsToBePaidToLenderPercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Proceeds To Be Paid To Lender, Percent </link:label>
<link:label id="lab_efoi_DebtInstrumentProceedsToBePaidToLenderPercent_documentation_en-US" xlink:label="lab_efoi_DebtInstrumentProceedsToBePaidToLenderPercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Proceeds To Be Paid To Lender, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DebtInstrumentProceedsToBePaidToLenderPercent" xlink:href="efoi-20201231.xsd#efoi_DebtInstrumentProceedsToBePaidToLenderPercent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DebtInstrumentProceedsToBePaidToLenderPercent" xlink:to="lab_efoi_DebtInstrumentProceedsToBePaidToLenderPercent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncreaseDecreaseInDeferredRevenue_7dad9e6d-ff30-41bc-b346-cabcaa546aab_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred revenue </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInDeferredRevenue_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Deferred Revenue </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredRevenue"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:to="lab_us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_e5a68cf1-8c88-4aa6-9777-1dcae32ea926_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Exercise Price Range [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Exercise Price Range [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:to="lab_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestrictedCashAndCashEquivalents_23ce3ca2-e67c-4c69-bc74-e7184c84c9b4_verboseLabel_en-US" xlink:label="lab_us-gaap_RestrictedCashAndCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted cash held in other assets </link:label>
<link:label id="lab_us-gaap_RestrictedCashAndCashEquivalents_label_en-US" xlink:label="lab_us-gaap_RestrictedCashAndCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted Cash and Cash Equivalents </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalents" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalents"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalents" xlink:to="lab_us-gaap_RestrictedCashAndCashEquivalents" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_InventoryValuationReserveMember_0e72f478-92aa-4fb4-9034-a90114f7c027_terseLabel_en-US" xlink:label="lab_us-gaap_InventoryValuationReserveMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reserve for excess, obsolete, and slow moving inventories </link:label>
<link:label id="lab_us-gaap_InventoryValuationReserveMember_label_en-US" xlink:label="lab_us-gaap_InventoryValuationReserveMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Reserve, Inventory [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryValuationReserveMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryValuationReserveMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InventoryValuationReserveMember" xlink:to="lab_us-gaap_InventoryValuationReserveMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet_d8f2b5bc-8c7a-4c11-a5ce-07fb8c52671d_totalLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net deferred tax assets </link:label>
<link:label id="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Net </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:to="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ConcentrationRiskByBenchmarkAxis_805e5f18-4e61-4edd-a4dd-8e3ddb1ea177_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Benchmark [Axis] </link:label>
<link:label id="lab_us-gaap_ConcentrationRiskByBenchmarkAxis_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Benchmark [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="lab_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CostOfGoodsAndServicesSold_c752ec37-5ee5-4358-ba67-c3c8543f7aa1_terseLabel_en-US" xlink:label="lab_us-gaap_CostOfGoodsAndServicesSold" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cost of sales </link:label>
<link:label id="lab_us-gaap_CostOfGoodsAndServicesSold_label_en-US" xlink:label="lab_us-gaap_CostOfGoodsAndServicesSold" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cost of Goods and Services Sold </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CostOfGoodsAndServicesSold" xlink:to="lab_us-gaap_CostOfGoodsAndServicesSold" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_d8335c61-23d3-45c0-8905-2673d49ad0e9_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:to="lab_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityAvailableInventoryNetRealizableValue_f205987d-66ce-42ca-89fc-472b4f513078_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAvailableInventoryNetRealizableValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percent of net realizable value of eligible inventory </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAvailableInventoryNetRealizableValue_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAvailableInventoryNetRealizableValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Available Inventory, Net Realizable Value </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAvailableInventoryNetRealizableValue_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAvailableInventoryNetRealizableValue" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Available Inventory, Net Realizable Value </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityAvailableInventoryNetRealizableValue" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityAvailableInventoryNetRealizableValue"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityAvailableInventoryNetRealizableValue" xlink:to="lab_efoi_LineOfCreditFacilityAvailableInventoryNetRealizableValue" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOrSaleOfEquity_a93048bc-a285-413d-9877-3d4caf67ca6c_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gross proceeds from equity issuance </link:label>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOrSaleOfEquity_label_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Issuance or Sale of Equity </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:to="lab_us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StatementEquityComponentsAxis_1c900e4e-c0d9-48c8-8f8a-2b0a9024b120_terseLabel_en-US" xlink:label="lab_us-gaap_StatementEquityComponentsAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Components [Axis] </link:label>
<link:label id="lab_us-gaap_StatementEquityComponentsAxis_label_en-US" xlink:label="lab_us-gaap_StatementEquityComponentsAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Components [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementEquityComponentsAxis" xlink:to="lab_us-gaap_StatementEquityComponentsAxis" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ExercisePriceRangeTwoMember_3f264cd0-b8c1-44a8-bbe7-941cf308a161_terseLabel_en-US" xlink:label="lab_efoi_ExercisePriceRangeTwoMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise price, range two </link:label>
<link:label id="lab_efoi_ExercisePriceRangeTwoMember_label_en-US" xlink:label="lab_efoi_ExercisePriceRangeTwoMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise Price Range Two [Member] </link:label>
<link:label id="lab_efoi_ExercisePriceRangeTwoMember_documentation_en-US" xlink:label="lab_efoi_ExercisePriceRangeTwoMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> The second exercise price range. </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ExercisePriceRangeTwoMember" xlink:href="efoi-20201231.xsd#efoi_ExercisePriceRangeTwoMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ExercisePriceRangeTwoMember" xlink:to="lab_efoi_ExercisePriceRangeTwoMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestrictedStockMember_1ffc6e7f-7dff-40b2-8f86-25a78cbc3486_terseLabel_en-US" xlink:label="lab_us-gaap_RestrictedStockMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted stock </link:label>
<link:label id="lab_us-gaap_RestrictedStockMember_label_en-US" xlink:label="lab_us-gaap_RestrictedStockMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted Stock [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestrictedStockMember" xlink:to="lab_us-gaap_RestrictedStockMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProceedsFromRepaymentsOfLinesOfCredit_340fa5e9-cfa9-4664-b591-5e6d559677d4_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromRepaymentsOfLinesOfCredit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net proceeds from (payment on) credit line borrowings </link:label>
<link:label id="lab_us-gaap_ProceedsFromRepaymentsOfLinesOfCredit_label_en-US" xlink:label="lab_us-gaap_ProceedsFromRepaymentsOfLinesOfCredit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from (Repayments of) Lines of Credit </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromRepaymentsOfLinesOfCredit" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromRepaymentsOfLinesOfCredit"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromRepaymentsOfLinesOfCredit" xlink:to="lab_us-gaap_ProceedsFromRepaymentsOfLinesOfCredit" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtInstrumentNameDomain_539001f9-77ab-4454-b391-2de89dbfbc1c_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentNameDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Name [Domain] </link:label>
<link:label id="lab_us-gaap_DebtInstrumentNameDomain_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentNameDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Name [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentNameDomain" xlink:to="lab_us-gaap_DebtInstrumentNameDomain" xlink:type="arc" order="1"/>
<link:label id="lab_srt_MinimumMember_3f2545d3-1221-42b0-afde-4054452a018d_terseLabel_en-US" xlink:label="lab_srt_MinimumMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Minimum </link:label>
<link:label id="lab_srt_MinimumMember_4a4b2374-61dc-48da-acac-4263ab8e7668_verboseLabel_en-US" xlink:label="lab_srt_MinimumMember" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Minimum [Member] </link:label>
<link:label id="lab_srt_MinimumMember_label_en-US" xlink:label="lab_srt_MinimumMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Minimum [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_MinimumMember" xlink:to="lab_srt_MinimumMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearTwo_f3f1d0d6-1a6a-468c-85d9-343ce0622756_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2022 </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearTwo_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Payments, Due in Rolling Year Two </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearTwo"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_b944b6f3-616a-4f5e-b3ff-8bd9840f2864_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment, net </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_16889c32-b97e-49e1-b926-3b7d0a59f2dc_totalLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment, net </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RepaymentsOfNotesPayable_35079849-5387-4754-93b1-2d15850cd494_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_RepaymentsOfNotesPayable" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments on the Iliad Note </link:label>
<link:label id="lab_us-gaap_RepaymentsOfNotesPayable_345c14e2-bea6-4b91-9a85-5255cd4d7bf7_terseLabel_en-US" xlink:label="lab_us-gaap_RepaymentsOfNotesPayable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments on the Iliad Note </link:label>
<link:label id="lab_us-gaap_RepaymentsOfNotesPayable_label_en-US" xlink:label="lab_us-gaap_RepaymentsOfNotesPayable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Repayments of Notes Payable </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfNotesPayable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfNotesPayable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RepaymentsOfNotesPayable" xlink:to="lab_us-gaap_RepaymentsOfNotesPayable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingLeaseLiabilityCurrent_11880f44-1aae-4b2e-a776-b866a6e09bfb_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease liabilities </link:label>
<link:label id="lab_us-gaap_OperatingLeaseLiabilityCurrent_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Liability, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiabilityCurrent" xlink:to="lab_us-gaap_OperatingLeaseLiabilityCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_90d86ee5-8ae2-4e19-ab85-ad07b09c7626_periodStartLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Beginning balance (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_0c7abccb-2389-4dc1-ac82-4905bb000f98_periodEndLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ending balance (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DebtInstrumentPrepaymentPremiumPercent_5f50e6b0-5463-48bc-b181-ec3f631b6f97_terseLabel_en-US" xlink:label="lab_efoi_DebtInstrumentPrepaymentPremiumPercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepayment premium </link:label>
<link:label id="lab_efoi_DebtInstrumentPrepaymentPremiumPercent_label_en-US" xlink:label="lab_efoi_DebtInstrumentPrepaymentPremiumPercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Prepayment Premium, Percent </link:label>
<link:label id="lab_efoi_DebtInstrumentPrepaymentPremiumPercent_documentation_en-US" xlink:label="lab_efoi_DebtInstrumentPrepaymentPremiumPercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Prepayment Premium, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DebtInstrumentPrepaymentPremiumPercent" xlink:href="efoi-20201231.xsd#efoi_DebtInstrumentPrepaymentPremiumPercent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DebtInstrumentPrepaymentPremiumPercent" xlink:to="lab_efoi_DebtInstrumentPrepaymentPremiumPercent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo_ce778efc-1f56-4d59-96ac-d3e4cf4f451e_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2022 </link:label>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Two </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_472cfc91-b596-4907-a36b-630367e08d92_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Canceled (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_0d6692fb-f9b4-4ddf-ba2c-9d8bfb00e31d_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions </link:label>
<link:label id="lab_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityInteractiveDataCurrent_0872e715-529b-4c9d-b558-8f622271d724_terseLabel_en-US" xlink:label="lab_dei_EntityInteractiveDataCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Interactive Data Current </link:label>
<link:label id="lab_dei_EntityInteractiveDataCurrent_label_en-US" xlink:label="lab_dei_EntityInteractiveDataCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Interactive Data Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityInteractiveDataCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityInteractiveDataCurrent" xlink:to="lab_dei_EntityInteractiveDataCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_country_US_2b86ab23-bc79-4db6-a6b5-0b12195ae672_terseLabel_en-US" xlink:label="lab_country_US" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> United States </link:label>
<link:label id="lab_country_US_label_en-US" xlink:label="lab_country_US" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> UNITED STATES </link:label>
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<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_country_US" xlink:to="lab_country_US" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_1ced4565-5b44-4f6b-ae7b-6e423d46881f_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercised (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_0b7ae69e-dce2-4dd6-b65c-14a96e53bd04_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash flows from operating activities: </link:label>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Operating Activities [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
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<link:label id="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock_897c102c-69fb-446c-9b2f-fb204934c4be_terseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stockholders' Equity </link:label>
<link:label id="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stockholders' Equity Note Disclosure [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityNoteDisclosureTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:to="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EmployeeStockOwnershipPlanESOPPlanDomain_d68e4b4b-d441-4c36-a006-05cee0a49c48_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeStockOwnershipPlanESOPPlanDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employee Stock Ownership Plan (ESOP), Plan [Domain] </link:label>
<link:label id="lab_us-gaap_EmployeeStockOwnershipPlanESOPPlanDomain_label_en-US" xlink:label="lab_us-gaap_EmployeeStockOwnershipPlanESOPPlanDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employee Stock Ownership Plan (ESOP), Plan [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOwnershipPlanESOPPlanDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOwnershipPlanESOPPlanDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeStockOwnershipPlanESOPPlanDomain" xlink:to="lab_us-gaap_EmployeeStockOwnershipPlanESOPPlanDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_440a504c-11bb-43be-8c11-d9b69be45ab6_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary of Option Activity </link:label>
<link:label id="lab_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Activity [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PurchaseObligation_1867238a-5e70-478c-b427-cc666f8e8077_terseLabel_en-US" xlink:label="lab_us-gaap_PurchaseObligation" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Outstanding purchase commitment </link:label>
<link:label id="lab_us-gaap_PurchaseObligation_label_en-US" xlink:label="lab_us-gaap_PurchaseObligation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Purchase Obligation </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PurchaseObligation" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PurchaseObligation"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PurchaseObligation" xlink:to="lab_us-gaap_PurchaseObligation" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccountsReceivableMember_79092fd9-0067-4da8-a1a7-4d4b29bbf22a_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsReceivableMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts receivable </link:label>
<link:label id="lab_us-gaap_AccountsReceivableMember_label_en-US" xlink:label="lab_us-gaap_AccountsReceivableMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsReceivableMember" xlink:to="lab_us-gaap_AccountsReceivableMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_ee2321ab-58b0-4fcd-bfcd-33454273f36b_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] </link:label>
<link:label id="lab_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_label_en-US" xlink:label="lab_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems"/>
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<link:label id="lab_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy_866908f4-3c6e-4b82-a022-321c363c3e50_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock-based compensation </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xlink:to="lab_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_MovementInValuationAllowancesAndReservesRollForward_393fcbce-137c-4389-90cf-a6cc6462e52b_terseLabel_en-US" xlink:label="lab_us-gaap_MovementInValuationAllowancesAndReservesRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] </link:label>
<link:label id="lab_us-gaap_MovementInValuationAllowancesAndReservesRollForward_label_en-US" xlink:label="lab_us-gaap_MovementInValuationAllowancesAndReservesRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MovementInValuationAllowancesAndReservesRollForward"/>
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<link:label id="lab_srt_NameOfMajorCustomerDomain_d792276d-55fb-410a-83c6-1303522a0d43_terseLabel_en-US" xlink:label="lab_srt_NameOfMajorCustomerDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer [Domain] </link:label>
<link:label id="lab_srt_NameOfMajorCustomerDomain_label_en-US" xlink:label="lab_srt_NameOfMajorCustomerDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_NameOfMajorCustomerDomain"/>
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<link:label id="lab_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_2dd07f27-f87a-487a-bbd5-aad33507c5b3_terseLabel_en-US" xlink:label="lab_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cumulative Effect, Period of Adoption, Adjustment </link:label>
<link:label id="lab_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_label_en-US" xlink:label="lab_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cumulative Effect, Period of Adoption, Adjustment [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
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<link:label id="lab_us-gaap_AdditionalPaidInCapitalCommonStock_075d6b1b-4770-4880-9e43-d4c90ca1e5de_terseLabel_en-US" xlink:label="lab_us-gaap_AdditionalPaidInCapitalCommonStock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additional paid-in capital </link:label>
<link:label id="lab_us-gaap_AdditionalPaidInCapitalCommonStock_label_en-US" xlink:label="lab_us-gaap_AdditionalPaidInCapitalCommonStock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additional Paid in Capital, Common Stock </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>
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<link:label id="lab_dei_EntityRegistrantName_0e71d0d7-9a08-4485-bc9b-4ddfa02be3bc_terseLabel_en-US" xlink:label="lab_dei_EntityRegistrantName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Registrant Name </link:label>
<link:label id="lab_dei_EntityRegistrantName_label_en-US" xlink:label="lab_dei_EntityRegistrantName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Registrant Name </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityRegistrantName"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityRegistrantName" xlink:to="lab_dei_EntityRegistrantName" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SubsequentEventTypeDomain_3d82d9ac-a91c-4a5c-81f6-8822aa83d790_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event Type [Domain] </link:label>
<link:label id="lab_us-gaap_SubsequentEventTypeDomain_label_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event Type [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventTypeDomain" xlink:to="lab_us-gaap_SubsequentEventTypeDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StatementOfStockholdersEquityAbstract_8f8c213e-e431-42cd-a9b2-5c4c1591e16f_terseLabel_en-US" xlink:label="lab_us-gaap_StatementOfStockholdersEquityAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Stockholders' Equity [Abstract] </link:label>
<link:label id="lab_us-gaap_StatementOfStockholdersEquityAbstract_label_en-US" xlink:label="lab_us-gaap_StatementOfStockholdersEquityAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Stockholders' Equity [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfStockholdersEquityAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementOfStockholdersEquityAbstract"/>
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<link:label id="lab_us-gaap_ConcentrationRiskLineItems_82cfeeac-1e79-4467-9222-030bfa01d591_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk [Line Items] </link:label>
<link:label id="lab_us-gaap_ConcentrationRiskLineItems_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskLineItems" xlink:to="lab_us-gaap_ConcentrationRiskLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccruedEmployeeBenefitsCurrent_f1f3ee3a-9b01-4afa-b6a4-15d88da812f1_terseLabel_en-US" xlink:label="lab_us-gaap_AccruedEmployeeBenefitsCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued payroll and related benefits </link:label>
<link:label id="lab_us-gaap_AccruedEmployeeBenefitsCurrent_label_en-US" xlink:label="lab_us-gaap_AccruedEmployeeBenefitsCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued Employee Benefits, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedEmployeeBenefitsCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedEmployeeBenefitsCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccruedEmployeeBenefitsCurrent" xlink:to="lab_us-gaap_AccruedEmployeeBenefitsCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtInstrumentFeeAmount_d2bd531b-6e85-4094-99bb-143510f18a60_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentFeeAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fee amount </link:label>
<link:label id="lab_us-gaap_DebtInstrumentFeeAmount_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentFeeAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Fee Amount </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFeeAmount" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFeeAmount"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentFeeAmount" xlink:to="lab_us-gaap_DebtInstrumentFeeAmount" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncomeTaxExaminationLineItems_12a66c6c-1ded-4881-a2ab-4ec32e94c16d_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxExaminationLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Examination [Line Items] </link:label>
<link:label id="lab_us-gaap_IncomeTaxExaminationLineItems_label_en-US" xlink:label="lab_us-gaap_IncomeTaxExaminationLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Examination [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExaminationLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems" xlink:to="lab_us-gaap_IncomeTaxExaminationLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AssetImpairmentCharges_3cb1aa6f-88fc-45c1-b903-135a37e283ea_terseLabel_en-US" xlink:label="lab_us-gaap_AssetImpairmentCharges" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss on impairment </link:label>
<link:label id="lab_us-gaap_AssetImpairmentCharges_label_en-US" xlink:label="lab_us-gaap_AssetImpairmentCharges" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Asset Impairment Charges </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetImpairmentCharges"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetImpairmentCharges" xlink:to="lab_us-gaap_AssetImpairmentCharges" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_FinanceLeaseRightOfUseAssetAccumulatedDepreciation_fa259784-abd6-4a1b-9c7a-37c09511465c_negatedTerseLabel_en-US" xlink:label="lab_efoi_FinanceLeaseRightOfUseAssetAccumulatedDepreciation" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Allowances for depreciation </link:label>
<link:label id="lab_efoi_FinanceLeaseRightOfUseAssetAccumulatedDepreciation_label_en-US" xlink:label="lab_efoi_FinanceLeaseRightOfUseAssetAccumulatedDepreciation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-Of-Use Asset, Accumulated Depreciation </link:label>
<link:label id="lab_efoi_FinanceLeaseRightOfUseAssetAccumulatedDepreciation_documentation_en-US" xlink:label="lab_efoi_FinanceLeaseRightOfUseAssetAccumulatedDepreciation" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-Of-Use Asset, Accumulated Depreciation </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_FinanceLeaseRightOfUseAssetAccumulatedDepreciation" xlink:href="efoi-20201231.xsd#efoi_FinanceLeaseRightOfUseAssetAccumulatedDepreciation"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_FinanceLeaseRightOfUseAssetAccumulatedDepreciation" xlink:to="lab_efoi_FinanceLeaseRightOfUseAssetAccumulatedDepreciation" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AdvertisingCostsPolicyTextBlock_22b74da4-cdbc-443e-bb7e-091a39f17256_terseLabel_en-US" xlink:label="lab_us-gaap_AdvertisingCostsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Advertising expenses </link:label>
<link:label id="lab_us-gaap_AdvertisingCostsPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_AdvertisingCostsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Advertising Cost [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvertisingCostsPolicyTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdvertisingCostsPolicyTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdvertisingCostsPolicyTextBlock" xlink:to="lab_us-gaap_AdvertisingCostsPolicyTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOfWarrants_92510804-013d-47ee-be6c-5c5d090724f8_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfWarrants" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from warrants </link:label>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOfWarrants_label_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfWarrants" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Issuance of Warrants </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfWarrants" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfWarrants"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromIssuanceOfWarrants" xlink:to="lab_us-gaap_ProceedsFromIssuanceOfWarrants" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_a71bc92f-874c-4469-bae3-524a758ad15f_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted Stock Outstanding </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeaseSubleaseIncome_4b5b7983-099e-431d-98ee-32aaf29191a7_negatedTerseLabel_en-US" xlink:label="lab_efoi_RestructuredLeaseSubleaseIncome" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Sublease income </link:label>
<link:label id="lab_efoi_RestructuredLeaseSubleaseIncome_label_en-US" xlink:label="lab_efoi_RestructuredLeaseSubleaseIncome" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Lease, Sublease Income </link:label>
<link:label id="lab_efoi_RestructuredLeaseSubleaseIncome_documentation_en-US" xlink:label="lab_efoi_RestructuredLeaseSubleaseIncome" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Lease, Sublease Income </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeaseSubleaseIncome" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeaseSubleaseIncome"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeaseSubleaseIncome" xlink:to="lab_efoi_RestructuredLeaseSubleaseIncome" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_be88fc19-e1b6-4cdb-9fb5-7d50216df7a9_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Exercise Price Per Share </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
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<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_2cc382b7-1ad8-45fa-b3cf-e6590ea9eafa_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise Price Range [Axis] </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise Price Range [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis"/>
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<link:label id="lab_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_8f741e49-e102-4ba9-af50-e1ebd249c150_negatedLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less imputed interest </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Undiscounted Excess Amount </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:to="lab_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_21c0c24d-7d31-497e-bab1-926d6dc6e84f_terseLabel_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Charges to Revenue/ Expense </link:label>
<link:label id="lab_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_label_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" xlink:to="lab_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_VehiclesMember_66724f85-eacd-4a94-9d77-a91b0ff617d1_terseLabel_en-US" xlink:label="lab_us-gaap_VehiclesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vehicles </link:label>
<link:label id="lab_us-gaap_VehiclesMember_label_en-US" xlink:label="lab_us-gaap_VehiclesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vehicles [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VehiclesMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VehiclesMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VehiclesMember" xlink:to="lab_us-gaap_VehiclesMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ResearchAndDevelopmentExpenseMember_14c59d00-26b2-4502-8e53-865504408295_terseLabel_en-US" xlink:label="lab_us-gaap_ResearchAndDevelopmentExpenseMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product development </link:label>
<link:label id="lab_us-gaap_ResearchAndDevelopmentExpenseMember_label_en-US" xlink:label="lab_us-gaap_ResearchAndDevelopmentExpenseMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Research and Development Expense [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ResearchAndDevelopmentExpenseMember" xlink:to="lab_us-gaap_ResearchAndDevelopmentExpenseMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_9c500c81-a46c-4959-8f75-8ade3549043b_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Conversion of notes to preferred stock </link:label>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Issued During Period, Value, Conversion of Convertible Securities </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:to="lab_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DebtInstrumentPeriodTwoMember_d448cdf0-a24d-4884-a9bd-7cb47b2234cb_terseLabel_en-US" xlink:label="lab_efoi_DebtInstrumentPeriodTwoMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Year Two </link:label>
<link:label id="lab_efoi_DebtInstrumentPeriodTwoMember_label_en-US" xlink:label="lab_efoi_DebtInstrumentPeriodTwoMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Period Two [Member] </link:label>
<link:label id="lab_efoi_DebtInstrumentPeriodTwoMember_documentation_en-US" xlink:label="lab_efoi_DebtInstrumentPeriodTwoMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Period Two [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DebtInstrumentPeriodTwoMember" xlink:href="efoi-20201231.xsd#efoi_DebtInstrumentPeriodTwoMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DebtInstrumentPeriodTwoMember" xlink:to="lab_efoi_DebtInstrumentPeriodTwoMember" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityIncorporationStateCountryCode_88c1e23f-88df-43ed-80e7-cb09129a5605_terseLabel_en-US" xlink:label="lab_dei_EntityIncorporationStateCountryCode" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Incorporation, State or Country Code </link:label>
<link:label id="lab_dei_EntityIncorporationStateCountryCode_label_en-US" xlink:label="lab_dei_EntityIncorporationStateCountryCode" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Incorporation, State or Country Code </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityIncorporationStateCountryCode"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityIncorporationStateCountryCode" xlink:to="lab_dei_EntityIncorporationStateCountryCode" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccountsReceivableNetCurrent_b0570f01-f6d3-4030-8ed5-17cae8db0fb0_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsReceivableNetCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trade accounts receivable, less allowances of $8 and $28, respectively </link:label>
<link:label id="lab_us-gaap_AccountsReceivableNetCurrent_label_en-US" xlink:label="lab_us-gaap_AccountsReceivableNetCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, after Allowance for Credit Loss, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableNetCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsReceivableNetCurrent" xlink:to="lab_us-gaap_AccountsReceivableNetCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_InventoryFinishedGoods_b825bb51-78d5-4e52-a2f4-b103b469eb40_terseLabel_en-US" xlink:label="lab_us-gaap_InventoryFinishedGoods" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finished goods </link:label>
<link:label id="lab_us-gaap_InventoryFinishedGoods_label_en-US" xlink:label="lab_us-gaap_InventoryFinishedGoods" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory, Finished Goods, Gross </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryFinishedGoods" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryFinishedGoods"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InventoryFinishedGoods" xlink:to="lab_us-gaap_InventoryFinishedGoods" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_fdb654f9-56f0-4f2e-8de9-1af16b79da0c_totalLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total future undiscounted lease payments </link:label>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, to be Paid </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProceedsFromSalesOfAssetsInvestingActivities_0736ab6b-fcd1-4fa6-b5ff-45d5bc32b81e_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromSalesOfAssetsInvestingActivities" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from the sale of property and equipment </link:label>
<link:label id="lab_us-gaap_ProceedsFromSalesOfAssetsInvestingActivities_label_en-US" xlink:label="lab_us-gaap_ProceedsFromSalesOfAssetsInvestingActivities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Sales of Assets, Investing Activities </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSalesOfAssetsInvestingActivities" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromSalesOfAssetsInvestingActivities"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromSalesOfAssetsInvestingActivities" xlink:to="lab_us-gaap_ProceedsFromSalesOfAssetsInvestingActivities" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringReserve_0edbc0c6-9cfe-47a6-8625-54d5c2fa2883_periodStartLabel_en-US" xlink:label="lab_us-gaap_RestructuringReserve" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Beginning balance </link:label>
<link:label id="lab_us-gaap_RestructuringReserve_70868de2-3d9c-42eb-8173-d1b59717c2f8_periodEndLabel_en-US" xlink:label="lab_us-gaap_RestructuringReserve" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ending balance </link:label>
<link:label id="lab_us-gaap_RestructuringReserve_label_en-US" xlink:label="lab_us-gaap_RestructuringReserve" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Reserve </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringReserve"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringReserve" xlink:to="lab_us-gaap_RestructuringReserve" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_872b7786-2021-4648-8ce9-830d704efb1c_terseLabel_en-US" xlink:label="lab_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustments for New Accounting Pronouncements [Axis] </link:label>
<link:label id="lab_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_label_en-US" xlink:label="lab_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Standards Update [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="lab_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock_33a2064e-0420-4733-b4ad-adbd7a98b908_terseLabel_en-US" xlink:label="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign currency translation </link:label>
<link:label id="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Currency Transactions and Translations Policy [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock" xlink:to="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingLossCarryforwardsLineItems_ca3b1527-8fbe-4c0c-bf48-ba415d70b285_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLossCarryforwardsLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Loss Carryforwards [Line Items] </link:label>
<link:label id="lab_us-gaap_OperatingLossCarryforwardsLineItems_label_en-US" xlink:label="lab_us-gaap_OperatingLossCarryforwardsLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Loss Carryforwards [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="lab_us-gaap_OperatingLossCarryforwardsLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccountingStandardsUpdate201602Member_4ec794b1-2241-4d1b-94dd-44a207d453b1_terseLabel_en-US" xlink:label="lab_us-gaap_AccountingStandardsUpdate201602Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Standards Update 2016-02 </link:label>
<link:label id="lab_us-gaap_AccountingStandardsUpdate201602Member_label_en-US" xlink:label="lab_us-gaap_AccountingStandardsUpdate201602Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Standards Update 2016-02 [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdate201602Member" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountingStandardsUpdate201602Member" xlink:to="lab_us-gaap_AccountingStandardsUpdate201602Member" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SubsidiarySaleOfStockAxis_265a697a-8ca2-4bcc-9586-ad4aa408f850_terseLabel_en-US" xlink:label="lab_us-gaap_SubsidiarySaleOfStockAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Sale of Stock [Axis] </link:label>
<link:label id="lab_us-gaap_SubsidiarySaleOfStockAxis_label_en-US" xlink:label="lab_us-gaap_SubsidiarySaleOfStockAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Sale of Stock [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis" xlink:to="lab_us-gaap_SubsidiarySaleOfStockAxis" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityAddressPostalZipCode_7920ce9f-4885-4cf5-885c-fb0cc50ef214_terseLabel_en-US" xlink:label="lab_dei_EntityAddressPostalZipCode" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, Postal Zip Code </link:label>
<link:label id="lab_dei_EntityAddressPostalZipCode_label_en-US" xlink:label="lab_dei_EntityAddressPostalZipCode" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, Postal Zip Code </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressPostalZipCode"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityAddressPostalZipCode" xlink:to="lab_dei_EntityAddressPostalZipCode" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OtherDeferredCompensationArrangementsLiabilityCurrent_145c7a41-73fa-4d86-bf47-59944f69e29d_periodStartLabel_en-US" xlink:label="lab_us-gaap_OtherDeferredCompensationArrangementsLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balance January 1, 2020 </link:label>
<link:label id="lab_us-gaap_OtherDeferredCompensationArrangementsLiabilityCurrent_845a5abd-86b3-4dbe-b4e1-6e68a5a4c14b_periodEndLabel_en-US" xlink:label="lab_us-gaap_OtherDeferredCompensationArrangementsLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balance September 30, 2020 </link:label>
<link:label id="lab_us-gaap_OtherDeferredCompensationArrangementsLiabilityCurrent_label_en-US" xlink:label="lab_us-gaap_OtherDeferredCompensationArrangementsLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Deferred Compensation Arrangements, Liability, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDeferredCompensationArrangementsLiabilityCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherDeferredCompensationArrangementsLiabilityCurrent"/>
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<link:label id="lab_us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted_37b0ec60-101f-49c9-97aa-e20dc096cd31_terseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Basic and diluted (in shares) </link:label>
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<link:label id="lab_us-gaap_RestructuringCosts_632a0912-cf74-4334-9070-969d36554dc3_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringCosts" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring </link:label>
<link:label id="lab_us-gaap_RestructuringCosts_label_en-US" xlink:label="lab_us-gaap_RestructuringCosts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Costs </link:label>
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<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsRollingMaturityAbstract_2a521214-ed63-4480-9582-b8e5daaf5796_terseLabel_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsRollingMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases Sublease Payments </link:label>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsRollingMaturityAbstract_label_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsRollingMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessor, Operating Lease, Payments, Rolling Maturity [Abstract] </link:label>
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<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_2615cd18-1931-43bd-a918-81c47bb494d7_terseLabel_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Purchase price of common stock, percent </link:label>
<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_label_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent </link:label>
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<link:label id="lab_us-gaap_CustomerDepositsCurrent_27969eab-07be-46a1-90a4-c92f91f97427_terseLabel_en-US" xlink:label="lab_us-gaap_CustomerDepositsCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Short-term deposits </link:label>
<link:label id="lab_us-gaap_CustomerDepositsCurrent_label_en-US" xlink:label="lab_us-gaap_CustomerDepositsCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer Deposits, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerDepositsCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerDepositsCurrent"/>
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<link:label id="lab_us-gaap_OtherPrepaidExpenseCurrent_5930fe15-662a-4a76-b9e5-46e67a2f4874_terseLabel_en-US" xlink:label="lab_us-gaap_OtherPrepaidExpenseCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid expenses </link:label>
<link:label id="lab_us-gaap_OtherPrepaidExpenseCurrent_label_en-US" xlink:label="lab_us-gaap_OtherPrepaidExpenseCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Prepaid Expense, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPrepaidExpenseCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherPrepaidExpenseCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherPrepaidExpenseCurrent" xlink:to="lab_us-gaap_OtherPrepaidExpenseCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringCostAndReserveAxis_8e0054ea-9b48-4f43-898f-b3179f1e59ba_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringCostAndReserveAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Type [Axis] </link:label>
<link:label id="lab_us-gaap_RestructuringCostAndReserveAxis_label_en-US" xlink:label="lab_us-gaap_RestructuringCostAndReserveAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Type [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
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<link:label id="lab_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_1cd670a7-2116-4a93-b727-b84493b90139_verboseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign currency translation adjustments </link:label>
<link:label id="lab_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_14e384a1-d5d9-4279-89ac-021e70312e03_terseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign currency translation adjustment </link:label>
<link:label id="lab_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_label_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent"/>
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<link:label id="lab_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_fa793967-320d-49f6-8f22-2e869686446a_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued Liabilities </link:label>
<link:label id="lab_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_label_en-US" xlink:label="lab_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock"/>
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<link:label id="lab_us-gaap_PaymentsForRestructuring_0810767f-cc59-434f-a116-abf4119a7272_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_PaymentsForRestructuring" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments </link:label>
<link:label id="lab_us-gaap_PaymentsForRestructuring_label_en-US" xlink:label="lab_us-gaap_PaymentsForRestructuring" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments for Restructuring </link:label>
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<link:label id="lab_dei_DocumentTransitionReport_e6b5bc3a-8cc4-430c-97a1-0185fda847a6_terseLabel_en-US" xlink:label="lab_dei_DocumentTransitionReport" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Transition Report </link:label>
<link:label id="lab_dei_DocumentTransitionReport_label_en-US" xlink:label="lab_dei_DocumentTransitionReport" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Transition Report </link:label>
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<link:label id="lab_efoi_JamesTuThroughFusionParkLLCMember_2a7434df-6c8a-4a5a-9676-fc39ed822bbd_terseLabel_en-US" xlink:label="lab_efoi_JamesTuThroughFusionParkLLCMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> James Tu Through Fusion Park LLC </link:label>
<link:label id="lab_efoi_JamesTuThroughFusionParkLLCMember_label_en-US" xlink:label="lab_efoi_JamesTuThroughFusionParkLLCMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> James Tu Through Fusion Park LLC [Member] </link:label>
<link:label id="lab_efoi_JamesTuThroughFusionParkLLCMember_documentation_en-US" xlink:label="lab_efoi_JamesTuThroughFusionParkLLCMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> James Tu Through Fusion Park LLC [Member] </link:label>
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<link:label id="lab_us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract_ccc0e8e2-6aa0-4989-beec-1fdef7bd11c1_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred: </link:label>
<link:label id="lab_us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract_label_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] </link:label>
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<link:label id="lab_us-gaap_IncomeTaxExaminationTable_f0423ce5-2561-41f4-8fd6-10532bf9d18f_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxExaminationTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Examination [Table] </link:label>
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<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_f6a58829-d5c5-4e28-bc86-b0afed6a2eff_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] </link:label>
<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_label_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] </link:label>
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<link:label id="lab_us-gaap_WarrantMember_fae44aa4-085b-4915-ac4f-dc3ffa00fc6d_terseLabel_en-US" xlink:label="lab_us-gaap_WarrantMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Warrant </link:label>
<link:label id="lab_us-gaap_WarrantMember_label_en-US" xlink:label="lab_us-gaap_WarrantMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Warrant [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WarrantMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WarrantMember" xlink:to="lab_us-gaap_WarrantMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_IncreaseDecreaseInProvisionForWarranties_b179ca43-d904-474e-af13-6b00bb8aefcd_terseLabel_en-US" xlink:label="lab_efoi_IncreaseDecreaseInProvisionForWarranties" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Provision for warranties </link:label>
<link:label id="lab_efoi_IncreaseDecreaseInProvisionForWarranties_label_en-US" xlink:label="lab_efoi_IncreaseDecreaseInProvisionForWarranties" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) In Provision For Warranties </link:label>
<link:label id="lab_efoi_IncreaseDecreaseInProvisionForWarranties_documentation_en-US" xlink:label="lab_efoi_IncreaseDecreaseInProvisionForWarranties" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) In Provision For Warranties </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_IncreaseDecreaseInProvisionForWarranties" xlink:href="efoi-20201231.xsd#efoi_IncreaseDecreaseInProvisionForWarranties"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_IncreaseDecreaseInProvisionForWarranties" xlink:to="lab_efoi_IncreaseDecreaseInProvisionForWarranties" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_3b08acae-558b-43a6-9592-2e04911b1096_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net operating loss </link:label>
<link:label id="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_89588e04-a9ec-49b6-8288-c9bab47baf1f_verboseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred tax assets, operating loss carry-forwards </link:label>
<link:label id="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Operating Loss Carryforwards </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:to="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_NonoperatingIncomeExpenseAbstract_7734c1c1-45a9-4a76-9e0a-b6e732f17537_terseLabel_en-US" xlink:label="lab_us-gaap_NonoperatingIncomeExpenseAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other expenses: </link:label>
<link:label id="lab_us-gaap_NonoperatingIncomeExpenseAbstract_label_en-US" xlink:label="lab_us-gaap_NonoperatingIncomeExpenseAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Nonoperating Income (Expense) [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpenseAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NonoperatingIncomeExpenseAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract" xlink:to="lab_us-gaap_NonoperatingIncomeExpenseAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RevenuePercentChange_220c0301-7351-41ff-b145-b9e31ee00659_terseLabel_en-US" xlink:label="lab_efoi_RevenuePercentChange" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Change in revenue, percent </link:label>
<link:label id="lab_efoi_RevenuePercentChange_label_en-US" xlink:label="lab_efoi_RevenuePercentChange" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue, Percent Change </link:label>
<link:label id="lab_efoi_RevenuePercentChange_documentation_en-US" xlink:label="lab_efoi_RevenuePercentChange" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue, Percent Change </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RevenuePercentChange" xlink:href="efoi-20201231.xsd#efoi_RevenuePercentChange"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RevenuePercentChange" xlink:to="lab_efoi_RevenuePercentChange" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtInstrumentFaceAmount_3cdc2220-56dd-459a-afc9-c4ae48b4465c_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentFaceAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Principal amount </link:label>
<link:label id="lab_us-gaap_DebtInstrumentFaceAmount_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentFaceAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Face Amount </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentFaceAmount" xlink:to="lab_us-gaap_DebtInstrumentFaceAmount" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_PercentageOfSeriesAPreferredStockEligibleToVote_cc6254f4-bcf3-48e0-8f0d-91754e2df8e7_terseLabel_en-US" xlink:label="lab_efoi_PercentageOfSeriesAPreferredStockEligibleToVote" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percentage of number of votes that each share of preferred stock holders are entitled to </link:label>
<link:label id="lab_efoi_PercentageOfSeriesAPreferredStockEligibleToVote_label_en-US" xlink:label="lab_efoi_PercentageOfSeriesAPreferredStockEligibleToVote" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percentage of Series A Preferred Stock Eligible to Vote </link:label>
<link:label id="lab_efoi_PercentageOfSeriesAPreferredStockEligibleToVote_documentation_en-US" xlink:label="lab_efoi_PercentageOfSeriesAPreferredStockEligibleToVote" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percentage of Series A Preferred Stock Eligible to Vote </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_PercentageOfSeriesAPreferredStockEligibleToVote" xlink:href="efoi-20201231.xsd#efoi_PercentageOfSeriesAPreferredStockEligibleToVote"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_PercentageOfSeriesAPreferredStockEligibleToVote" xlink:to="lab_efoi_PercentageOfSeriesAPreferredStockEligibleToVote" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract_747a8695-01f9-41f6-9d72-e93165e3ec9f_terseLabel_en-US" xlink:label="lab_us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current: </link:label>
<link:label id="lab_us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract_label_en-US" xlink:label="lab_us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current Income Tax Expense (Benefit), Continuing Operations [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:to="lab_us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_7c7acfac-3ffc-4b96-83ec-8ffb2ea24632_negatedLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Canceled (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ImpairmentEffectsOnEarningsPerShareTable_93e6780b-a633-41f3-92cb-098ee36de524_terseLabel_en-US" xlink:label="lab_us-gaap_ImpairmentEffectsOnEarningsPerShareTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Impairment Effects on Earnings Per Share [Table] </link:label>
<link:label id="lab_us-gaap_ImpairmentEffectsOnEarningsPerShareTable_label_en-US" xlink:label="lab_us-gaap_ImpairmentEffectsOnEarningsPerShareTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Impairment Effects on Earnings Per Share [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentEffectsOnEarningsPerShareTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ImpairmentEffectsOnEarningsPerShareTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ImpairmentEffectsOnEarningsPerShareTable" xlink:to="lab_us-gaap_ImpairmentEffectsOnEarningsPerShareTable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts_1678c787-797f-4508-9858-f38e74c7b93e_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Offering costs on issuance of common stock and warrants </link:label>
<link:label id="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts_label_en-US" xlink:label="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts" xlink:to="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_InventoryReserveRollForward_8ef49bbb-e56a-4235-befc-be8f178964d8_terseLabel_en-US" xlink:label="lab_efoi_InventoryReserveRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory, Reserve [Roll Forward] </link:label>
<link:label id="lab_efoi_InventoryReserveRollForward_label_en-US" xlink:label="lab_efoi_InventoryReserveRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory, Reserve [Roll Forward] </link:label>
<link:label id="lab_efoi_InventoryReserveRollForward_documentation_en-US" xlink:label="lab_efoi_InventoryReserveRollForward" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory, Reserve </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_InventoryReserveRollForward" xlink:href="efoi-20201231.xsd#efoi_InventoryReserveRollForward"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_InventoryReserveRollForward" xlink:to="lab_efoi_InventoryReserveRollForward" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SubsequentEventLineItems_f54d1801-19f2-4aaf-9598-fc1a0548a802_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event [Line Items] </link:label>
<link:label id="lab_us-gaap_SubsequentEventLineItems_label_en-US" xlink:label="lab_us-gaap_SubsequentEventLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventLineItems" xlink:to="lab_us-gaap_SubsequentEventLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccountingStandardsUpdateExtensibleList_0e0c9137-d116-4704-82ee-3fe7a980c641_terseLabel_en-US" xlink:label="lab_us-gaap_AccountingStandardsUpdateExtensibleList" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Standards Update [Extensible List] </link:label>
<link:label id="lab_us-gaap_AccountingStandardsUpdateExtensibleList_label_en-US" xlink:label="lab_us-gaap_AccountingStandardsUpdateExtensibleList" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Standards Update [Extensible List] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdateExtensibleList" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountingStandardsUpdateExtensibleList"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountingStandardsUpdateExtensibleList" xlink:to="lab_us-gaap_AccountingStandardsUpdateExtensibleList" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_110f37c7-3bc1-4d0c-84c0-0ec75321d6af_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Granted (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityOverdraftFeePercent_1ce1eb36-ca72-46e6-9d23-6825fe43d920_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityOverdraftFeePercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Overdraft fee </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityOverdraftFeePercent_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityOverdraftFeePercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Overdraft Fee, Percent </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityOverdraftFeePercent_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityOverdraftFeePercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Overdraft Fee, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityOverdraftFeePercent" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityOverdraftFeePercent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityOverdraftFeePercent" xlink:to="lab_efoi_LineOfCreditFacilityOverdraftFeePercent" xlink:type="arc" order="1"/>
<link:label id="lab_srt_CumulativeEffectPeriodOfAdoptionAxis_f717bcfa-cb46-4d94-879f-cc4c28c11501_terseLabel_en-US" xlink:label="lab_srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cumulative Effect, Period of Adoption [Axis] </link:label>
<link:label id="lab_srt_CumulativeEffectPeriodOfAdoptionAxis_label_en-US" xlink:label="lab_srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cumulative Effect, Period of Adoption [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:to="lab_srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CustomerConcentrationRiskMember_ea636cab-ade1-4c84-bfbd-47cd556f4a78_terseLabel_en-US" xlink:label="lab_us-gaap_CustomerConcentrationRiskMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer concentration risk </link:label>
<link:label id="lab_us-gaap_CustomerConcentrationRiskMember_label_en-US" xlink:label="lab_us-gaap_CustomerConcentrationRiskMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer Concentration Risk [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerConcentrationRiskMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CustomerConcentrationRiskMember" xlink:to="lab_us-gaap_CustomerConcentrationRiskMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_b837cb72-a493-43cf-b8fc-d9521a953702_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vested and expected to vest (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CreditFacilityDomain_0398834f-4d59-45a3-a363-69ddfa866222_terseLabel_en-US" xlink:label="lab_us-gaap_CreditFacilityDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Facility [Domain] </link:label>
<link:label id="lab_us-gaap_CreditFacilityDomain_label_en-US" xlink:label="lab_us-gaap_CreditFacilityDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Facility [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CreditFacilityDomain" xlink:to="lab_us-gaap_CreditFacilityDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_e3e3cdaf-fd70-4dec-af7e-30726d67d96d_terseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Diluted (in shares) </link:label>
<link:label id="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_label_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Number of Shares Outstanding, Diluted </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtInstrumentConvertibleConversionPrice1_5ec82b0c-5df5-4a91-a5a4-ec99b6ac9ae0_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Conversion price (in dollars per share) </link:label>
<link:label id="lab_us-gaap_DebtInstrumentConvertibleConversionPrice1_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Convertible, Conversion Price </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:to="lab_us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EarningsPerShareBasic_fa15b490-e5e6-40ee-ab21-7aadd83626de_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasic" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net loss per share, basic (in dollars per share) </link:label>
<link:label id="lab_us-gaap_EarningsPerShareBasic_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasic" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share, Basic </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasic"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareBasic" xlink:to="lab_us-gaap_EarningsPerShareBasic" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_23d74b23-3f54-4489-8b1b-1f35a1f48fa9_terseLabel_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expected life of option (in years) </link:label>
<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_label_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:to="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityFileNumber_f443d7d8-d5af-4dbc-bafe-56a39a238ed2_terseLabel_en-US" xlink:label="lab_dei_EntityFileNumber" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity File Number </link:label>
<link:label id="lab_dei_EntityFileNumber_label_en-US" xlink:label="lab_dei_EntityFileNumber" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity File Number </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityFileNumber"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityFileNumber" xlink:to="lab_dei_EntityFileNumber" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_113b6188-e77c-4a8a-a11b-9053087b1296_negatedLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Canceled (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtDisclosureAbstract_94b48e3d-9a84-4b55-a69c-18ecabfed0d4_terseLabel_en-US" xlink:label="lab_us-gaap_DebtDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Disclosure [Abstract] </link:label>
<link:label id="lab_us-gaap_DebtDisclosureAbstract_label_en-US" xlink:label="lab_us-gaap_DebtDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Disclosure [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtDisclosureAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtDisclosureAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtDisclosureAbstract" xlink:to="lab_us-gaap_DebtDisclosureAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_302d986f-9c54-4e4f-b3dc-84c965874c92_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease, weighted average remaining lease term </link:label>
<link:label id="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Weighted Average Remaining Lease Term </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:to="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringPlanAxis_335cc8f6-f959-40b2-9894-ae1590b47863_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringPlanAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Plan [Axis] </link:label>
<link:label id="lab_us-gaap_RestructuringPlanAxis_label_en-US" xlink:label="lab_us-gaap_RestructuringPlanAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Plan [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringPlanAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringPlanAxis" xlink:to="lab_us-gaap_RestructuringPlanAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_956b8729-4964-4e74-9ef7-67c4ddc70767_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_OperatingLeaseLiabilityIncludingRestructuredLeases_34fd1bd6-af65-4a6c-9924-c49dc728aa11_totalLabel_en-US" xlink:label="lab_efoi_OperatingLeaseLiabilityIncludingRestructuredLeases" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease liabilities, total </link:label>
<link:label id="lab_efoi_OperatingLeaseLiabilityIncludingRestructuredLeases_label_en-US" xlink:label="lab_efoi_OperatingLeaseLiabilityIncludingRestructuredLeases" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Liability, Including Restructured Leases </link:label>
<link:label id="lab_efoi_OperatingLeaseLiabilityIncludingRestructuredLeases_documentation_en-US" xlink:label="lab_efoi_OperatingLeaseLiabilityIncludingRestructuredLeases" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Liability, Including Restructured Leases </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_OperatingLeaseLiabilityIncludingRestructuredLeases" xlink:href="efoi-20201231.xsd#efoi_OperatingLeaseLiabilityIncludingRestructuredLeases"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_OperatingLeaseLiabilityIncludingRestructuredLeases" xlink:to="lab_efoi_OperatingLeaseLiabilityIncludingRestructuredLeases" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities_b72c04c1-e26a-4178-8b6d-a412ea77bdef_totalLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net cash provided by financing activities </link:label>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Financing Activities </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths_705a67fb-d417-413e-89c7-5a883f813816_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2021 </link:label>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, Payments, Due Next Rolling Twelve Months </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued_dd025b3e-1307-4c82-a7b5-cf05d450b638_terseLabel_en-US" xlink:label="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Warrant liability - issuance </link:label>
<link:label id="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued_label_en-US" xlink:label="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustments to Additional Paid in Capital, Warrant Issued </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued" xlink:to="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_InventoryValuationReserves_33f1e5b0-1144-4d69-b2b3-098843f42842_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_InventoryValuationReserves" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reserve for excess, obsolete, and slow-moving inventories </link:label>
<link:label id="lab_us-gaap_InventoryValuationReserves_label_en-US" xlink:label="lab_us-gaap_InventoryValuationReserves" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Valuation Reserves </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryValuationReserves" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryValuationReserves"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InventoryValuationReserves" xlink:to="lab_us-gaap_InventoryValuationReserves" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AllocatedShareBasedCompensationExpense_9af94232-c93b-4f85-9f4a-282802e73871_terseLabel_en-US" xlink:label="lab_us-gaap_AllocatedShareBasedCompensationExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total stock-based compensation </link:label>
<link:label id="lab_us-gaap_AllocatedShareBasedCompensationExpense_label_en-US" xlink:label="lab_us-gaap_AllocatedShareBasedCompensationExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Expense </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AllocatedShareBasedCompensationExpense" xlink:to="lab_us-gaap_AllocatedShareBasedCompensationExpense" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityAvailableInventory_04d79782-87b8-42e4-bf10-2f15a26c4994_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAvailableInventory" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Eligible inventory </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAvailableInventory_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAvailableInventory" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Available Inventory </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAvailableInventory_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAvailableInventory" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Available Inventory </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityAvailableInventory" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityAvailableInventory"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityAvailableInventory" xlink:to="lab_efoi_LineOfCreditFacilityAvailableInventory" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_0abe9725-a1dd-4018-8a89-3d43e7c4b422_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Issuance of common stock under employee stock option and stock purchase plans </link:label>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Issued During Period, Value, Employee Stock Purchase Plan </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan" xlink:to="lab_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract_c0c8c920-6f89-4c08-b3e1-f281365db583_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted average shares of common shares outstanding: </link:label>
<link:label id="lab_us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract" xlink:to="lab_us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CommonStockValue_7f4df4c2-7b97-49f5-9ce1-6ae3d35f70e5_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock, par value $0.0001 per share: Authorized: 30,000,000 shares in 2019 and 2018 Issued and outstanding: 11,710,549 at December 31, 2016 and 11.648,978 at December 31, 2015 </link:label>
<link:label id="lab_us-gaap_CommonStockValue_label_en-US" xlink:label="lab_us-gaap_CommonStockValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Value, Issued </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockValue"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockValue" xlink:to="lab_us-gaap_CommonStockValue" xlink:type="arc" order="1"/>
<link:label id="lab_dei_DocumentFiscalYearFocus_4a6f0a8c-5268-44ee-acd6-2163ad9a6c93_terseLabel_en-US" xlink:label="lab_dei_DocumentFiscalYearFocus" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Fiscal Year Focus </link:label>
<link:label id="lab_dei_DocumentFiscalYearFocus_label_en-US" xlink:label="lab_dei_DocumentFiscalYearFocus" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Fiscal Year Focus </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentFiscalYearFocus"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentFiscalYearFocus" xlink:to="lab_dei_DocumentFiscalYearFocus" xlink:type="arc" order="1"/>
<link:label id="lab_dei_DocumentAnnualReport_5123951f-c7fc-406c-a5c5-6892985ce6d3_terseLabel_en-US" xlink:label="lab_dei_DocumentAnnualReport" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Annual Report </link:label>
<link:label id="lab_dei_DocumentAnnualReport_label_en-US" xlink:label="lab_dei_DocumentAnnualReport" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Annual Report </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentAnnualReport" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentAnnualReport"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentAnnualReport" xlink:to="lab_dei_DocumentAnnualReport" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_ebe74f51-d46e-43ec-b13e-eb5094b4a62f_terseLabel_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Intrinsic value of options exercisable </link:label>
<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_label_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:to="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:type="arc" order="1"/>
<link:label id="lab_srt_ValuationAndQualifyingAccountsAbstract_acb42eb6-f310-425a-84de-23af83025d4d_terseLabel_en-US" xlink:label="lab_srt_ValuationAndQualifyingAccountsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] </link:label>
<link:label id="lab_srt_ValuationAndQualifyingAccountsAbstract_label_en-US" xlink:label="lab_srt_ValuationAndQualifyingAccountsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsAbstract" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ValuationAndQualifyingAccountsAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ValuationAndQualifyingAccountsAbstract" xlink:to="lab_srt_ValuationAndQualifyingAccountsAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree_1d848912-0d23-4467-a3b6-c82166d2f86a_terseLabel_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2023 </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree_label_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due In Rolling Year Three </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree_documentation_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due In Rolling Year Three </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree" xlink:to="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityCurrentReportingStatus_0dd01428-8fab-46ff-9cba-52be03f8726b_terseLabel_en-US" xlink:label="lab_dei_EntityCurrentReportingStatus" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Current Reporting Status </link:label>
<link:label id="lab_dei_EntityCurrentReportingStatus_label_en-US" xlink:label="lab_dei_EntityCurrentReportingStatus" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Current Reporting Status </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityCurrentReportingStatus"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityCurrentReportingStatus" xlink:to="lab_dei_EntityCurrentReportingStatus" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified_75bb7302-79bb-4d12-af2d-01f51118a5a5_terseLabel_en-US" xlink:label="lab_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Warrant liability - modification </link:label>
<link:label id="lab_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified_138abcce-3ea6-4975-bc47-b10a4cdc4059_verboseLabel_en-US" xlink:label="lab_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Warrant liability reclassified into equity </link:label>
<link:label id="lab_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified_d3ad92f5-a924-4ccd-b15c-95b0bab5b948_negatedTerseLabel_en-US" xlink:label="lab_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Warrant liability - modification </link:label>
<link:label id="lab_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified_label_en-US" xlink:label="lab_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustments to Additional Paid in Capital, Warrant Reclassified </link:label>
<link:label id="lab_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified_documentation_en-US" xlink:label="lab_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustments to Additional Paid in Capital, Warrant Reclassified </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified" xlink:href="efoi-20201231.xsd#efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified" xlink:to="lab_efoi_AdjustmentsToAdditionalPaidInCapitalWarrantReclassified" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFour_d3d32840-eec2-42b4-9897-b88b791f8bb5_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFour" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2024 </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFour_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFour" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Payments, Due in Rolling Year Four </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFour" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFour"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFour" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearFour" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProceedsFromOtherDebt_739f294d-e3a2-4912-ae99-6517101b315b_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromOtherDebt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from the Iliad Note </link:label>
<link:label id="lab_us-gaap_ProceedsFromOtherDebt_label_en-US" xlink:label="lab_us-gaap_ProceedsFromOtherDebt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Other Debt </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromOtherDebt" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromOtherDebt"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromOtherDebt" xlink:to="lab_us-gaap_ProceedsFromOtherDebt" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsOutstandingAbstract_b2ce2080-1c8b-411f-9714-6c69f6f37768_terseLabel_en-US" xlink:label="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsOutstandingAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> OPTIONS OUTSTANDING </link:label>
<link:label id="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsOutstandingAbstract_label_en-US" xlink:label="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsOutstandingAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Options Outstanding [Abstract] </link:label>
<link:label id="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsOutstandingAbstract_documentation_en-US" xlink:label="lab_efoi_SharebasedCompensationSharesAuthorizedunderStockOptionPlansExercisePriceRangeOptionsOutstandingAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Options Outstanding [Abstract] </link:label>
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<link:label id="lab_us-gaap_MediumtermNotesCurrent_05c2bc53-751c-4d0e-87c3-f559f4fbcfd1_terseLabel_en-US" xlink:label="lab_us-gaap_MediumtermNotesCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Iliad note, net of discount and loan origination fees </link:label>
<link:label id="lab_us-gaap_MediumtermNotesCurrent_label_en-US" xlink:label="lab_us-gaap_MediumtermNotesCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Medium-term Notes, Current </link:label>
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<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MediumtermNotesCurrent" xlink:to="lab_us-gaap_MediumtermNotesCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SubsequentEventTable_b1e91671-26e8-451f-88d8-5e077e4fdb89_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event [Table] </link:label>
<link:label id="lab_us-gaap_SubsequentEventTable_label_en-US" xlink:label="lab_us-gaap_SubsequentEventTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventTable" xlink:to="lab_us-gaap_SubsequentEventTable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EarningsPerSharePolicyTextBlock_d7060a0f-5ba4-4305-9bfa-3786a9e5ea30_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerSharePolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net income (loss) per share </link:label>
<link:label id="lab_us-gaap_EarningsPerSharePolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_EarningsPerSharePolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share, Policy [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerSharePolicyTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerSharePolicyTextBlock"/>
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<link:label id="lab_us-gaap_DebtInstrumentTable_df3f8af3-46f6-4983-a4cd-622e062bfb09_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Long-term Debt Instruments [Table] </link:label>
<link:label id="lab_us-gaap_DebtInstrumentTable_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Long-term Debt Instruments [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentTable" xlink:to="lab_us-gaap_DebtInstrumentTable" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityBorrowingCapacityValueOfAccountsReceivablePercent_ebc3faa7-abcc-4920-aa56-562dc29d192a_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityBorrowingCapacityValueOfAccountsReceivablePercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Face value of accounts receivable </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityBorrowingCapacityValueOfAccountsReceivablePercent_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityBorrowingCapacityValueOfAccountsReceivablePercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Borrowing Capacity, Value Of Accounts Receivable, Percent </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityBorrowingCapacityValueOfAccountsReceivablePercent_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityBorrowingCapacityValueOfAccountsReceivablePercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Borrowing Capacity, Value Of Accounts Receivable, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityBorrowingCapacityValueOfAccountsReceivablePercent" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityBorrowingCapacityValueOfAccountsReceivablePercent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityBorrowingCapacityValueOfAccountsReceivablePercent" xlink:to="lab_efoi_LineOfCreditFacilityBorrowingCapacityValueOfAccountsReceivablePercent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_c7fffeb7-f819-424e-8800-c6b72a02575c_verboseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Granted (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
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<link:label id="lab_us-gaap_InventoryDisclosureAbstract_4681ddf1-f55a-41f3-8a19-6634430af380_terseLabel_en-US" xlink:label="lab_us-gaap_InventoryDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Disclosure [Abstract] </link:label>
<link:label id="lab_us-gaap_InventoryDisclosureAbstract_label_en-US" xlink:label="lab_us-gaap_InventoryDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Disclosure [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryDisclosureAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryDisclosureAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InventoryDisclosureAbstract" xlink:to="lab_us-gaap_InventoryDisclosureAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_81bf761d-d279-418d-9cd9-162ae40a7a3c_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash flows from investing activities: </link:label>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Investing Activities [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
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<link:label id="lab_us-gaap_CommonStockSharesIssued_169f63c4-6f45-4053-ad43-e93106ed8be2_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockSharesIssued" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock, number of shares issued </link:label>
<link:label id="lab_us-gaap_CommonStockSharesIssued_label_en-US" xlink:label="lab_us-gaap_CommonStockSharesIssued" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Shares, Issued </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockSharesIssued" xlink:to="lab_us-gaap_CommonStockSharesIssued" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_bf876592-74f4-4982-a071-a77483e431f0_verboseLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash </link:label>
<link:label id="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_label_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents, at Carrying Value </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
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<link:label id="lab_efoi_PaymentsRelatedToExpensesForRegisteredDirectOfferingAndConcurrentPrivatePlacement_ed47b4c2-c758-4ff9-b43f-e28bd0e7b2f9_terseLabel_en-US" xlink:label="lab_efoi_PaymentsRelatedToExpensesForRegisteredDirectOfferingAndConcurrentPrivatePlacement" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amount paid related to expenses for registered direct offering and concurrent private placement </link:label>
<link:label id="lab_efoi_PaymentsRelatedToExpensesForRegisteredDirectOfferingAndConcurrentPrivatePlacement_label_en-US" xlink:label="lab_efoi_PaymentsRelatedToExpensesForRegisteredDirectOfferingAndConcurrentPrivatePlacement" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments Related To Expenses For Registered Direct Offering And Concurrent Private Placement </link:label>
<link:label id="lab_efoi_PaymentsRelatedToExpensesForRegisteredDirectOfferingAndConcurrentPrivatePlacement_documentation_en-US" xlink:label="lab_efoi_PaymentsRelatedToExpensesForRegisteredDirectOfferingAndConcurrentPrivatePlacement" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments Related To Expenses For Registered Direct Offering And Concurrent Private Placement </link:label>
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<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_d9becd45-3240-490e-955f-762451435950_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of Shares Outstanding (in shares) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions"/>
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<link:label id="lab_us-gaap_OperatingLeaseLiability_fb68fb6b-004c-4925-93f3-93a62cc5587c_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease liabilities </link:label>
<link:label id="lab_us-gaap_OperatingLeaseLiability_d5b4975d-3d91-46ad-a0a5-169ee91d95c4_verboseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total lease obligations </link:label>
<link:label id="lab_us-gaap_OperatingLeaseLiability_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Liability </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiability" xlink:to="lab_us-gaap_OperatingLeaseLiability" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredTaxLiabilities_83c8d15f-a260-4b84-b5bb-b11ebc7ffe60_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilities" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net deferred tax liabilities </link:label>
<link:label id="lab_us-gaap_DeferredTaxLiabilities_label_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Liabilities, Net </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilities" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilities"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilities" xlink:to="lab_us-gaap_DeferredTaxLiabilities" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo_7759ca29-6bbd-47fb-8c33-d760f716ffa3_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2022 </link:label>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo_label_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessor, Operating Lease, Payments to be Received, Rolling Year Two </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo" xlink:to="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SegmentReportingAbstract_b8957f78-be65-44a5-8e3d-11e845565abc_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentReportingAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Reporting [Abstract] </link:label>
<link:label id="lab_us-gaap_SegmentReportingAbstract_label_en-US" xlink:label="lab_us-gaap_SegmentReportingAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Reporting [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentReportingAbstract" xlink:to="lab_us-gaap_SegmentReportingAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_76a128d2-34ec-4d1f-aabe-8f71353d184e_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts receivable </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Accounts Receivable </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:to="lab_us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtInstrumentLineItems_3dc781de-9658-4939-8f16-79735ebf5ab6_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument [Line Items] </link:label>
<link:label id="lab_us-gaap_DebtInstrumentLineItems_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="lab_us-gaap_DebtInstrumentLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract_61db7976-4c07-40ee-a1ef-8039b25cc043_terseLabel_en-US" xlink:label="lab_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Comprehensive Income [Abstract] </link:label>
<link:label id="lab_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract_label_en-US" xlink:label="lab_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Comprehensive Income [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:to="lab_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockholdersEquity_5821f95d-1b20-46bd-8a74-a39d38705b2e_totalLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquity" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total stockholders' equity </link:label>
<link:label id="lab_us-gaap_StockholdersEquity_6819ca45-2e1e-426f-a643-1fc4b10ff21d_periodStartLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquity" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Beginning balance </link:label>
<link:label id="lab_us-gaap_StockholdersEquity_c37814c1-661d-464f-9611-959c513e6bb0_periodEndLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquity" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ending balance </link:label>
<link:label id="lab_us-gaap_StockholdersEquity_59bcab3d-8502-4b81-9f43-f9fdd7d41a74_verboseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquity" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stockholders' equity </link:label>
<link:label id="lab_us-gaap_StockholdersEquity_label_en-US" xlink:label="lab_us-gaap_StockholdersEquity" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stockholders' Equity Attributable to Parent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquity" xlink:to="lab_us-gaap_StockholdersEquity" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ToolingMember_d2078955-44ef-49ba-bb5f-54431dcf42c3_terseLabel_en-US" xlink:label="lab_efoi_ToolingMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tooling </link:label>
<link:label id="lab_efoi_ToolingMember_label_en-US" xlink:label="lab_efoi_ToolingMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tooling [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ToolingMember" xlink:href="efoi-20201231.xsd#efoi_ToolingMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ToolingMember" xlink:to="lab_efoi_ToolingMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_NatureOfOperations_5f130145-1409-49c8-94f9-e251a494b855_terseLabel_en-US" xlink:label="lab_us-gaap_NatureOfOperations" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Nature of Operations </link:label>
<link:label id="lab_us-gaap_NatureOfOperations_label_en-US" xlink:label="lab_us-gaap_NatureOfOperations" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Nature of Operations [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NatureOfOperations" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NatureOfOperations"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NatureOfOperations" xlink:to="lab_us-gaap_NatureOfOperations" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PaymentsOfStockIssuanceCosts_8a7ed2f2-6dcf-4800-9d45-5ec342e13f5f_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_PaymentsOfStockIssuanceCosts" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Offering costs paid on the issuance of common stock and warrants </link:label>
<link:label id="lab_us-gaap_PaymentsOfStockIssuanceCosts_label_en-US" xlink:label="lab_us-gaap_PaymentsOfStockIssuanceCosts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments of Stock Issuance Costs </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfStockIssuanceCosts"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsOfStockIssuanceCosts" xlink:to="lab_us-gaap_PaymentsOfStockIssuanceCosts" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ConcentrationRiskTypeDomain_eeb8abf3-3f5b-4ed9-92c6-aea9ef782ec8_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskTypeDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Type [Domain] </link:label>
<link:label id="lab_us-gaap_ConcentrationRiskTypeDomain_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskTypeDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Type [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain" xlink:to="lab_us-gaap_ConcentrationRiskTypeDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_b20e6493-0e82-4516-b288-29b96f3d9e41_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of positions eliminated </link:label>
<link:label id="lab_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_label_en-US" xlink:label="lab_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring and Related Cost, Number of Positions Eliminated </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated" xlink:to="lab_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_CommunalInternationalLtdMember_9d0910ef-078c-462e-b2b6-b96a42bc3c5f_terseLabel_en-US" xlink:label="lab_efoi_CommunalInternationalLtdMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Communal International Ltd. </link:label>
<link:label id="lab_efoi_CommunalInternationalLtdMember_label_en-US" xlink:label="lab_efoi_CommunalInternationalLtdMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Communal International Ltd. [Member] </link:label>
<link:label id="lab_efoi_CommunalInternationalLtdMember_documentation_en-US" xlink:label="lab_efoi_CommunalInternationalLtdMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Communal International Ltd. </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_CommunalInternationalLtdMember" xlink:href="efoi-20201231.xsd#efoi_CommunalInternationalLtdMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_CommunalInternationalLtdMember" xlink:to="lab_efoi_CommunalInternationalLtdMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquity_d8917d7a-3587-4f3e-9164-727bf8ff42fa_totalLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquity" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total liabilities and stockholders' equity </link:label>
<link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquity_label_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquity" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities and Equity </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="lab_us-gaap_LiabilitiesAndStockholdersEquity" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_edc9d2be-aa38-4a17-b8d2-487de204fee4_terseLabel_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated other comprehensive loss </link:label>
<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_label_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated Other Comprehensive Income (Loss), Net of Tax </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:to="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncomeTaxDisclosureTextBlock_b2ffa566-cb34-43e5-90d7-8a8d567af174_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Taxes </link:label>
<link:label id="lab_us-gaap_IncomeTaxDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_IncomeTaxDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Disclosure [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxDisclosureTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxDisclosureTextBlock" xlink:to="lab_us-gaap_IncomeTaxDisclosureTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_InventoryRawMaterials_1365063e-10b4-42b8-a459-e4c1c1f8d455_terseLabel_en-US" xlink:label="lab_us-gaap_InventoryRawMaterials" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Raw materials </link:label>
<link:label id="lab_us-gaap_InventoryRawMaterials_label_en-US" xlink:label="lab_us-gaap_InventoryRawMaterials" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory, Raw Materials, Gross </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryRawMaterials" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryRawMaterials"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InventoryRawMaterials" xlink:to="lab_us-gaap_InventoryRawMaterials" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityAddressCityOrTown_57820866-f850-4544-aad4-40b5bc91d8eb_terseLabel_en-US" xlink:label="lab_dei_EntityAddressCityOrTown" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, City or Town </link:label>
<link:label id="lab_dei_EntityAddressCityOrTown_label_en-US" xlink:label="lab_dei_EntityAddressCityOrTown" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, City or Town </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressCityOrTown"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityAddressCityOrTown" xlink:to="lab_dei_EntityAddressCityOrTown" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestrictedStockUnitsRSUMember_f96aee99-f12f-498a-a7a8-34e9fa5e404f_terseLabel_en-US" xlink:label="lab_us-gaap_RestrictedStockUnitsRSUMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted Stock Units (RSUs) </link:label>
<link:label id="lab_us-gaap_RestrictedStockUnitsRSUMember_label_en-US" xlink:label="lab_us-gaap_RestrictedStockUnitsRSUMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted Stock Units (RSUs) [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:to="lab_us-gaap_RestrictedStockUnitsRSUMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingLeaseCost_da467d59-90c8-4ce4-bed5-78236699e0a9_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseCost" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease cost </link:label>
<link:label id="lab_us-gaap_OperatingLeaseCost_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseCost" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Cost </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseCost"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseCost" xlink:to="lab_us-gaap_OperatingLeaseCost" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour_2fbf8e7a-6d15-4395-99ce-422955912b00_terseLabel_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2024 </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour_label_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due In Rolling Year Four </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour_documentation_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due In Rolling Year Four </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:to="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths_203e349e-2e70-4ae1-a0d5-ab1ddc3b4091_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2021 </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Payments, Due in Next Rolling Twelve Months </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInNextRollingTwelveMonths" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_TypeOfAdoptionMember_966ac198-f537-4dde-985e-4e66f9716fca_terseLabel_en-US" xlink:label="lab_us-gaap_TypeOfAdoptionMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Type of Adoption [Domain] </link:label>
<link:label id="lab_us-gaap_TypeOfAdoptionMember_label_en-US" xlink:label="lab_us-gaap_TypeOfAdoptionMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Standards Update [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfAdoptionMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TypeOfAdoptionMember" xlink:to="lab_us-gaap_TypeOfAdoptionMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable_1410642e-5fee-45ba-ba0a-e06f22a318be_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Business Acquisitions by Acquisition, Contingent Consideration [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Business Acquisitions by Acquisition, Contingent Consideration [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable" xlink:to="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ShipbuilderForUSNavyMember_dd8634b5-6e55-4d62-a65e-2e89adffd91d_terseLabel_en-US" xlink:label="lab_efoi_ShipbuilderForUSNavyMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Shipbuilder For U.S. Navy </link:label>
<link:label id="lab_efoi_ShipbuilderForUSNavyMember_label_en-US" xlink:label="lab_efoi_ShipbuilderForUSNavyMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Shipbuilder For U.S. Navy [Member] </link:label>
<link:label id="lab_efoi_ShipbuilderForUSNavyMember_documentation_en-US" xlink:label="lab_efoi_ShipbuilderForUSNavyMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Shipbuilder For U.S. Navy </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ShipbuilderForUSNavyMember" xlink:href="efoi-20201231.xsd#efoi_ShipbuilderForUSNavyMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ShipbuilderForUSNavyMember" xlink:to="lab_efoi_ShipbuilderForUSNavyMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_3ddcbfa9-044b-41d9-ac35-efb8c0904029_terseLabel_en-US" xlink:label="lab_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Antidilutive securities excluded from computation of earnings per share (number of shares) </link:label>
<link:label id="lab_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_label_en-US" xlink:label="lab_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:to="lab_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_529c6d25-58dd-4c79-8f3e-7ea6e55576cf_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance lease, weighted average remaining lease term </link:label>
<link:label id="lab_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Weighted Average Remaining Lease Term </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:to="lab_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityAnnualFeePercent_bfbb8b3c-6de5-48ef-9126-668532ed864b_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAnnualFeePercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Annual fee </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAnnualFeePercent_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAnnualFeePercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Annual Fee, Percent </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAnnualFeePercent_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAnnualFeePercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Annual Fee, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityAnnualFeePercent" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityAnnualFeePercent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityAnnualFeePercent" xlink:to="lab_efoi_LineOfCreditFacilityAnnualFeePercent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_5bdc80fc-749e-4076-a409-5e6c7bad6e35_negatedLabel_en-US" xlink:label="lab_us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss on dispositions of property and equipment </link:label>
<link:label id="lab_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_label_en-US" xlink:label="lab_us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gain (Loss) on Disposition of Property Plant Equipment </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:to="lab_us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EquityComponentDomain_fe7fd190-df13-4215-9a12-d6e01ec4ee1b_terseLabel_en-US" xlink:label="lab_us-gaap_EquityComponentDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Component [Domain] </link:label>
<link:label id="lab_us-gaap_EquityComponentDomain_label_en-US" xlink:label="lab_us-gaap_EquityComponentDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Component [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityComponentDomain" xlink:to="lab_us-gaap_EquityComponentDomain" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityCollateralManagementFeePercent_8caf1f18-64d3-49b2-afbe-1f06b989024c_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityCollateralManagementFeePercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Collateral management fee </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityCollateralManagementFeePercent_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityCollateralManagementFeePercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Collateral Management Fee, Percent </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityCollateralManagementFeePercent_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityCollateralManagementFeePercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Collateral Management Fee, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityCollateralManagementFeePercent" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityCollateralManagementFeePercent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityCollateralManagementFeePercent" xlink:to="lab_efoi_LineOfCreditFacilityCollateralManagementFeePercent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_MediumtermNotesNoncurrent_06180138-bf06-4672-ae15-63ae4e918bd5_terseLabel_en-US" xlink:label="lab_us-gaap_MediumtermNotesNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Iliad note, net of current maturities </link:label>
<link:label id="lab_us-gaap_MediumtermNotesNoncurrent_label_en-US" xlink:label="lab_us-gaap_MediumtermNotesNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Medium-term Notes, Noncurrent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MediumtermNotesNoncurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MediumtermNotesNoncurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MediumtermNotesNoncurrent" xlink:to="lab_us-gaap_MediumtermNotesNoncurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredTaxAssetsValuationAllowance_f453a5ce-00b9-42ce-b723-19b635d4c009_negatedLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Valuation allowance </link:label>
<link:label id="lab_us-gaap_DeferredTaxAssetsValuationAllowance_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Valuation Allowance </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:to="lab_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredTaxLiabilitiesLeasingArrangements_0d38fa06-e862-4aee-b900-a3c0a7cb39d9_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesLeasingArrangements" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Right-of-use-asset </link:label>
<link:label id="lab_us-gaap_DeferredTaxLiabilitiesLeasingArrangements_label_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesLeasingArrangements" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Liabilities, Leasing Arrangements </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesLeasingArrangements" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilitiesLeasingArrangements"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesLeasingArrangements" xlink:to="lab_us-gaap_DeferredTaxLiabilitiesLeasingArrangements" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_OperatingLeaseReceivable_98bbeb28-5d6d-4cb1-99ba-cc1a5d58ece1_negatedTerseLabel_en-US" xlink:label="lab_efoi_OperatingLeaseReceivable" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total lease obligations </link:label>
<link:label id="lab_efoi_OperatingLeaseReceivable_label_en-US" xlink:label="lab_efoi_OperatingLeaseReceivable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Receivable </link:label>
<link:label id="lab_efoi_OperatingLeaseReceivable_documentation_en-US" xlink:label="lab_efoi_OperatingLeaseReceivable" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Receivable </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_OperatingLeaseReceivable" xlink:href="efoi-20201231.xsd#efoi_OperatingLeaseReceivable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_OperatingLeaseReceivable" xlink:to="lab_efoi_OperatingLeaseReceivable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LiabilitiesAbstract_48110ac5-45ae-4b89-a21a-8729899e323b_terseLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> LIABILITIES </link:label>
<link:label id="lab_us-gaap_LiabilitiesAbstract_label_en-US" xlink:label="lab_us-gaap_LiabilitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesAbstract" xlink:to="lab_us-gaap_LiabilitiesAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_GrossProfit_c7ab0e4a-4e00-4350-974d-0785b5f5c0b6_totalLabel_en-US" xlink:label="lab_us-gaap_GrossProfit" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gross profit </link:label>
<link:label id="lab_us-gaap_GrossProfit_f439ddb4-a576-4ee8-a6a6-ddaf4108d4e4_terseLabel_en-US" xlink:label="lab_us-gaap_GrossProfit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gross profit </link:label>
<link:label id="lab_us-gaap_GrossProfit_label_en-US" xlink:label="lab_us-gaap_GrossProfit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gross Profit </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GrossProfit"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GrossProfit" xlink:to="lab_us-gaap_GrossProfit" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ConstructionInProgressMember_cf055e57-1d04-46ad-980a-2fc5193118be_terseLabel_en-US" xlink:label="lab_us-gaap_ConstructionInProgressMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction in progress </link:label>
<link:label id="lab_us-gaap_ConstructionInProgressMember_label_en-US" xlink:label="lab_us-gaap_ConstructionInProgressMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction in Progress [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConstructionInProgressMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConstructionInProgressMember" xlink:to="lab_us-gaap_ConstructionInProgressMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_A2017RestructuringPlanMember_5b7ec076-e819-4848-8dc4-2fcd0296c160_terseLabel_en-US" xlink:label="lab_efoi_A2017RestructuringPlanMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2017 Restructuring Plan </link:label>
<link:label id="lab_efoi_A2017RestructuringPlanMember_label_en-US" xlink:label="lab_efoi_A2017RestructuringPlanMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2017 Restructuring Plan [Member] </link:label>
<link:label id="lab_efoi_A2017RestructuringPlanMember_documentation_en-US" xlink:label="lab_efoi_A2017RestructuringPlanMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2017 Restructuring Plan [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_A2017RestructuringPlanMember" xlink:href="efoi-20201231.xsd#efoi_A2017RestructuringPlanMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_A2017RestructuringPlanMember" xlink:to="lab_efoi_A2017RestructuringPlanMember" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityTaxIdentificationNumber_82ec7034-e1ff-4d75-aac7-c1b853241d3a_terseLabel_en-US" xlink:label="lab_dei_EntityTaxIdentificationNumber" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Tax Identification Number </link:label>
<link:label id="lab_dei_EntityTaxIdentificationNumber_label_en-US" xlink:label="lab_dei_EntityTaxIdentificationNumber" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Tax Identification Number </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityTaxIdentificationNumber"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityTaxIdentificationNumber" xlink:to="lab_dei_EntityTaxIdentificationNumber" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PrepaidInsurance_2b6d0867-c609-4ea8-aef1-f075b927c04d_terseLabel_en-US" xlink:label="lab_us-gaap_PrepaidInsurance" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid insurance </link:label>
<link:label id="lab_us-gaap_PrepaidInsurance_label_en-US" xlink:label="lab_us-gaap_PrepaidInsurance" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid Insurance </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidInsurance" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrepaidInsurance"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PrepaidInsurance" xlink:to="lab_us-gaap_PrepaidInsurance" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock_7cefc055-f72d-4d22-8cf4-156a67dc362e_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue recognition </link:label>
<link:label id="lab_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue from Contract with Customer [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerPolicyTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:to="lab_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeLeaseDescriptionTable_18293a9a-c3ff-4c3f-93ba-858828b20d54_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeLeaseDescriptionTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Lease, Description [Table] </link:label>
<link:label id="lab_us-gaap_LesseeLeaseDescriptionTable_label_en-US" xlink:label="lab_us-gaap_LesseeLeaseDescriptionTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Lease, Description [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable" xlink:to="lab_us-gaap_LesseeLeaseDescriptionTable" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ReceivablesFacilityMember_1c741f4b-77ad-4d1a-aa1b-982d1a81b3d8_terseLabel_en-US" xlink:label="lab_efoi_ReceivablesFacilityMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Receivables Facility </link:label>
<link:label id="lab_efoi_ReceivablesFacilityMember_label_en-US" xlink:label="lab_efoi_ReceivablesFacilityMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Receivables Facility [Member] </link:label>
<link:label id="lab_efoi_ReceivablesFacilityMember_documentation_en-US" xlink:label="lab_efoi_ReceivablesFacilityMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Receivables Facility </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ReceivablesFacilityMember" xlink:href="efoi-20201231.xsd#efoi_ReceivablesFacilityMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_ReceivablesFacilityMember" xlink:to="lab_efoi_ReceivablesFacilityMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_NetIncomeLoss_889d8979-4e2e-4370-9a65-8ab5df7e556c_totalLabel_en-US" xlink:label="lab_us-gaap_NetIncomeLoss" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net loss </link:label>
<link:label id="lab_us-gaap_NetIncomeLoss_b7645bd0-bd51-4c73-9a78-da9e2e6715da_terseLabel_en-US" xlink:label="lab_us-gaap_NetIncomeLoss" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net loss </link:label>
<link:label id="lab_us-gaap_NetIncomeLoss_label_en-US" xlink:label="lab_us-gaap_NetIncomeLoss" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Income (Loss) Attributable to Parent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetIncomeLoss" xlink:to="lab_us-gaap_NetIncomeLoss" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityNoncurrent_6f3501b2-3f52-4ab7-a191-c4c0c08267d0_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance lease liabilities, net of current portion </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityNoncurrent_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Noncurrent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:to="lab_us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_c9d1d732-e88c-4254-84c4-8faea6aa5618_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Change in operating assets and liabilities: </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Operating Capital [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_srt_EquityMethodInvesteeNameDomain_b7ad0695-ecb9-490f-85ba-fc2317803de7_terseLabel_en-US" xlink:label="lab_srt_EquityMethodInvesteeNameDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investment, Name [Domain] </link:label>
<link:label id="lab_srt_EquityMethodInvesteeNameDomain_label_en-US" xlink:label="lab_srt_EquityMethodInvesteeNameDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investment, Name [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_EquityMethodInvesteeNameDomain" xlink:to="lab_srt_EquityMethodInvesteeNameDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LondonInterbankOfferedRateLIBORMember_ce9c988f-d30e-4cef-acf2-74a5c93d9bf1_terseLabel_en-US" xlink:label="lab_us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> London Interbank Offered Rate (LIBOR) </link:label>
<link:label id="lab_us-gaap_LondonInterbankOfferedRateLIBORMember_label_en-US" xlink:label="lab_us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> London Interbank Offered Rate (LIBOR) [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:to="lab_us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_InventoryDisclosureTextBlock_1087ec56-ffac-4173-9d29-94a7ff50db7f_terseLabel_en-US" xlink:label="lab_us-gaap_InventoryDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventories </link:label>
<link:label id="lab_us-gaap_InventoryDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_InventoryDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Disclosure [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryDisclosureTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InventoryDisclosureTextBlock" xlink:to="lab_us-gaap_InventoryDisclosureTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtInstrumentUnamortizedPremium_3dada42f-9185-40bc-8af3-e71b03004234_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentUnamortizedPremium" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Original issue discount </link:label>
<link:label id="lab_us-gaap_DebtInstrumentUnamortizedPremium_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentUnamortizedPremium" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Unamortized Premium </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedPremium" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentUnamortizedPremium"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedPremium" xlink:to="lab_us-gaap_DebtInstrumentUnamortizedPremium" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_InventoryValuationReservesRawMaterials_7efa9845-82d0-459a-b467-67da1aba9acc_negatedPeriodStartLabel_en-US" xlink:label="lab_efoi_InventoryValuationReservesRawMaterials" xlink:role="http://www.xbrl.org/2009/role/negatedPeriodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Beginning balance </link:label>
<link:label id="lab_efoi_InventoryValuationReservesRawMaterials_3c4eae9b-e172-42c8-abac-215935006820_negatedPeriodEndLabel_en-US" xlink:label="lab_efoi_InventoryValuationReservesRawMaterials" xlink:role="http://www.xbrl.org/2009/role/negatedPeriodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reserves for excess, obsolete, and slow-moving inventories </link:label>
<link:label id="lab_efoi_InventoryValuationReservesRawMaterials_label_en-US" xlink:label="lab_efoi_InventoryValuationReservesRawMaterials" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Valuation Reserves, Raw Materials </link:label>
<link:label id="lab_efoi_InventoryValuationReservesRawMaterials_documentation_en-US" xlink:label="lab_efoi_InventoryValuationReservesRawMaterials" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory Valuation Reserves, Raw Materials </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_InventoryValuationReservesRawMaterials" xlink:href="efoi-20201231.xsd#efoi_InventoryValuationReservesRawMaterials"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_InventoryValuationReservesRawMaterials" xlink:to="lab_efoi_InventoryValuationReservesRawMaterials" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LeasesAbstract_9ca59550-3d98-4db4-926a-7395b3446b57_terseLabel_en-US" xlink:label="lab_us-gaap_LeasesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leases [Abstract] </link:label>
<link:label id="lab_us-gaap_LeasesAbstract_label_en-US" xlink:label="lab_us-gaap_LeasesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leases [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeasesAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeasesAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeasesAbstract" xlink:to="lab_us-gaap_LeasesAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LongtermDebtTypeAxis_9d5f518b-ff14-4b19-b85b-d66f79132fa4_terseLabel_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term Debt, Type [Axis] </link:label>
<link:label id="lab_us-gaap_LongtermDebtTypeAxis_label_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term Debt, Type [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongtermDebtTypeAxis" xlink:to="lab_us-gaap_LongtermDebtTypeAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AssetsCurrent_eae54859-7617-4788-a1d1-8125026c87b8_totalLabel_en-US" xlink:label="lab_us-gaap_AssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total current assets </link:label>
<link:label id="lab_us-gaap_AssetsCurrent_label_en-US" xlink:label="lab_us-gaap_AssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsCurrent" xlink:to="lab_us-gaap_AssetsCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_dei_CurrentFiscalYearEndDate_274ac798-e6cd-4821-a532-a04e812d2392_terseLabel_en-US" xlink:label="lab_dei_CurrentFiscalYearEndDate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current Fiscal Year End Date </link:label>
<link:label id="lab_dei_CurrentFiscalYearEndDate_label_en-US" xlink:label="lab_dei_CurrentFiscalYearEndDate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current Fiscal Year End Date </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_CurrentFiscalYearEndDate"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_CurrentFiscalYearEndDate" xlink:to="lab_dei_CurrentFiscalYearEndDate" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingExpensesAbstract_cbe45a34-acd8-4ff7-844c-c40a5f7ac7b7_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingExpensesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating expenses: </link:label>
<link:label id="lab_us-gaap_OperatingExpensesAbstract_label_en-US" xlink:label="lab_us-gaap_OperatingExpensesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Expenses [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingExpensesAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingExpensesAbstract" xlink:to="lab_us-gaap_OperatingExpensesAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EarningsPerShareAbstract_d2c1b06e-deed-42f0-976d-b5c16466f959_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Numerator: </link:label>
<link:label id="lab_us-gaap_EarningsPerShareAbstract_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareAbstract" xlink:to="lab_us-gaap_EarningsPerShareAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OperatingLossCarryforwards_b7eceb3d-8388-4a0d-af37-4b0d16b99127_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLossCarryforwards" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating loss carry-forwards </link:label>
<link:label id="lab_us-gaap_OperatingLossCarryforwards_label_en-US" xlink:label="lab_us-gaap_OperatingLossCarryforwards" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Loss Carryforwards </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLossCarryforwards"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLossCarryforwards" xlink:to="lab_us-gaap_OperatingLossCarryforwards" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_8dda8861-afd2-431d-978e-48f2f5837375_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Deferred Tax Assets </link:label>
<link:label id="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Deferred Tax Assets and Liabilities [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseLiability_f5c36edd-4154-433d-ad4d-884e9916e54e_verboseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance lease liabilities </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiability_084b1212-6a17-4b6a-941d-59a01b5bd126_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total lease obligations </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiability_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiability"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiability" xlink:to="lab_us-gaap_FinanceLeaseLiability" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_74d9c161-538d-4e71-a75b-909db3127091_totalLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment at cost </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_eae7eeb1-b7f8-4d9d-950c-c9ae54316efb_terseLabel_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> State taxes (net of federal tax benefit) </link:label>
<link:label id="lab_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_label_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockholdersEquityAbstract_4150eeae-7b01-4fb4-922a-7777684227a8_terseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> STOCKHOLDERS’ EQUITY </link:label>
<link:label id="lab_us-gaap_StockholdersEquityAbstract_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stockholders' Equity Attributable to Parent [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityAbstract" xlink:to="lab_us-gaap_StockholdersEquityAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RegionalCommercialLightingRetrofitCompanyMember_f64b7427-e445-4d2d-94da-522c5115217b_terseLabel_en-US" xlink:label="lab_efoi_RegionalCommercialLightingRetrofitCompanyMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Regional Commercial Lighting Retrofit Company </link:label>
<link:label id="lab_efoi_RegionalCommercialLightingRetrofitCompanyMember_label_en-US" xlink:label="lab_efoi_RegionalCommercialLightingRetrofitCompanyMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Regional Commercial Lighting Retrofit Company [Member] </link:label>
<link:label id="lab_efoi_RegionalCommercialLightingRetrofitCompanyMember_documentation_en-US" xlink:label="lab_efoi_RegionalCommercialLightingRetrofitCompanyMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Regional Commercial Lighting Retrofit Company </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RegionalCommercialLightingRetrofitCompanyMember" xlink:href="efoi-20201231.xsd#efoi_RegionalCommercialLightingRetrofitCompanyMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RegionalCommercialLightingRetrofitCompanyMember" xlink:to="lab_efoi_RegionalCommercialLightingRetrofitCompanyMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CashAndCashEquivalentsAbstract_49277c5f-f5f8-4fa4-9cf1-405c5b3efcdc_terseLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Classification of cash and restricted cash: </link:label>
<link:label id="lab_us-gaap_CashAndCashEquivalentsAbstract_label_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsAbstract" xlink:to="lab_us-gaap_CashAndCashEquivalentsAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_AustinCreditFacilityMember_c36f693c-5517-433e-a1f4-caf448eebc9e_terseLabel_en-US" xlink:label="lab_efoi_AustinCreditFacilityMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Austin Credit Facility </link:label>
<link:label id="lab_efoi_AustinCreditFacilityMember_label_en-US" xlink:label="lab_efoi_AustinCreditFacilityMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Austin Credit Facility [Member] </link:label>
<link:label id="lab_efoi_AustinCreditFacilityMember_documentation_en-US" xlink:label="lab_efoi_AustinCreditFacilityMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Austin Credit Facility </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_AustinCreditFacilityMember" xlink:href="efoi-20201231.xsd#efoi_AustinCreditFacilityMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_AustinCreditFacilityMember" xlink:to="lab_efoi_AustinCreditFacilityMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_bda89f55-bd7d-4c61-a5ca-74db9d8cbe71_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of Options </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:type="arc" order="1"/>
<link:label id="lab_dei_DocumentFiscalPeriodFocus_f8f76678-c1ea-4a3f-9aa5-e2e97e3fa37c_terseLabel_en-US" xlink:label="lab_dei_DocumentFiscalPeriodFocus" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Fiscal Period Focus </link:label>
<link:label id="lab_dei_DocumentFiscalPeriodFocus_label_en-US" xlink:label="lab_dei_DocumentFiscalPeriodFocus" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Fiscal Period Focus </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentFiscalPeriodFocus"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentFiscalPeriodFocus" xlink:to="lab_dei_DocumentFiscalPeriodFocus" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_OtherLEDProductsMember_1bf72ce3-146d-472f-af4a-e3c3c6de1e8a_terseLabel_en-US" xlink:label="lab_efoi_OtherLEDProductsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other LED Products </link:label>
<link:label id="lab_efoi_OtherLEDProductsMember_label_en-US" xlink:label="lab_efoi_OtherLEDProductsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other LED Products [Member] </link:label>
<link:label id="lab_efoi_OtherLEDProductsMember_documentation_en-US" xlink:label="lab_efoi_OtherLEDProductsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other LED Products [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_OtherLEDProductsMember" xlink:href="efoi-20201231.xsd#efoi_OtherLEDProductsMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_OtherLEDProductsMember" xlink:to="lab_efoi_OtherLEDProductsMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_PaymentsForClearingFees_83874674-288e-4ee4-8751-3795178914a3_terseLabel_en-US" xlink:label="lab_efoi_PaymentsForClearingFees" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amount paid for clearing fees </link:label>
<link:label id="lab_efoi_PaymentsForClearingFees_label_en-US" xlink:label="lab_efoi_PaymentsForClearingFees" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments For Clearing Fees </link:label>
<link:label id="lab_efoi_PaymentsForClearingFees_documentation_en-US" xlink:label="lab_efoi_PaymentsForClearingFees" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments For Clearing Fees </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_PaymentsForClearingFees" xlink:href="efoi-20201231.xsd#efoi_PaymentsForClearingFees"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_PaymentsForClearingFees" xlink:to="lab_efoi_PaymentsForClearingFees" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_AccumulatedInterestOnSubordinatedDebt_642f4366-bbcf-4ff0-ae77-d81cb8004c30_terseLabel_en-US" xlink:label="lab_efoi_AccumulatedInterestOnSubordinatedDebt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated interest </link:label>
<link:label id="lab_efoi_AccumulatedInterestOnSubordinatedDebt_label_en-US" xlink:label="lab_efoi_AccumulatedInterestOnSubordinatedDebt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated Interest on Subordinated Debt </link:label>
<link:label id="lab_efoi_AccumulatedInterestOnSubordinatedDebt_documentation_en-US" xlink:label="lab_efoi_AccumulatedInterestOnSubordinatedDebt" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated Interest on Subordinated Debt </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_AccumulatedInterestOnSubordinatedDebt" xlink:href="efoi-20201231.xsd#efoi_AccumulatedInterestOnSubordinatedDebt"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_AccumulatedInterestOnSubordinatedDebt" xlink:to="lab_efoi_AccumulatedInterestOnSubordinatedDebt" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtConversionOriginalDebtInterestRateOfDebt_24a05d47-1514-4de2-9863-53057025d9d3_terseLabel_en-US" xlink:label="lab_us-gaap_DebtConversionOriginalDebtInterestRateOfDebt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest rate on convertible notes </link:label>
<link:label id="lab_us-gaap_DebtConversionOriginalDebtInterestRateOfDebt_label_en-US" xlink:label="lab_us-gaap_DebtConversionOriginalDebtInterestRateOfDebt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Conversion, Original Debt, Interest Rate of Debt </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionOriginalDebtInterestRateOfDebt" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtConversionOriginalDebtInterestRateOfDebt"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtConversionOriginalDebtInterestRateOfDebt" xlink:to="lab_us-gaap_DebtConversionOriginalDebtInterestRateOfDebt" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DistributorToUSNavyCombinedWithSalesToShipbuildersMember_55288fa6-e96d-49dc-b69a-c7558ae3336b_terseLabel_en-US" xlink:label="lab_efoi_DistributorToUSNavyCombinedWithSalesToShipbuildersMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Distributor To U.S. Navy Combined With Sales To Shipbuilders </link:label>
<link:label id="lab_efoi_DistributorToUSNavyCombinedWithSalesToShipbuildersMember_label_en-US" xlink:label="lab_efoi_DistributorToUSNavyCombinedWithSalesToShipbuildersMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Distributor To U.S. Navy Combined With Sales To Shipbuilders [Member] </link:label>
<link:label id="lab_efoi_DistributorToUSNavyCombinedWithSalesToShipbuildersMember_documentation_en-US" xlink:label="lab_efoi_DistributorToUSNavyCombinedWithSalesToShipbuildersMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Distributor To U.S. Navy Combined With Sales To Shipbuilders </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DistributorToUSNavyCombinedWithSalesToShipbuildersMember" xlink:href="efoi-20201231.xsd#efoi_DistributorToUSNavyCombinedWithSalesToShipbuildersMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DistributorToUSNavyCombinedWithSalesToShipbuildersMember" xlink:to="lab_efoi_DistributorToUSNavyCombinedWithSalesToShipbuildersMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_59b83565-13a2-43fd-b6ce-620256a1a0d4_negatedLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less: accumulated depreciation </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearThree_d78fac34-f043-4141-bebe-4bfd678a7553_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearThree" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2023 </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearThree_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearThree" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Payments, Due in Rolling Year Three </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearThree" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearThree"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearThree" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueInRollingYearThree" xlink:type="arc" order="1"/>
<link:label id="lab_srt_ValuationAndQualifyingAccountsDisclosureTable_82afcc97-8cfd-4251-a794-4e7277d332ac_terseLabel_en-US" xlink:label="lab_srt_ValuationAndQualifyingAccountsDisclosureTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] </link:label>
<link:label id="lab_srt_ValuationAndQualifyingAccountsDisclosureTable_label_en-US" xlink:label="lab_srt_ValuationAndQualifyingAccountsDisclosureTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureTable" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ValuationAndQualifyingAccountsDisclosureTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureTable" xlink:to="lab_srt_ValuationAndQualifyingAccountsDisclosureTable" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LongLivedAssetsPolicyPolicyTextBlock_43c6b1b3-95e4-4d2a-a757-da48adb646b5_terseLabel_en-US" xlink:label="lab_efoi_LongLivedAssetsPolicyPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-lived assets </link:label>
<link:label id="lab_efoi_LongLivedAssetsPolicyPolicyTextBlock_label_en-US" xlink:label="lab_efoi_LongLivedAssetsPolicyPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long Lived Assets Policy [Policy Text Block] </link:label>
<link:label id="lab_efoi_LongLivedAssetsPolicyPolicyTextBlock_documentation_en-US" xlink:label="lab_efoi_LongLivedAssetsPolicyPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Disclosure of accounting policy for property, plant and equipment as well as goodwill and intangible assets, which may include the basis of such assets, depreciation methods used and estimated useful lives, the entity's capitalization policy, including its accounting treatment for costs incurred for repairs and maintenance activities, whether such asset balances include capitalized interest and the method by which such is calculated, how disposals of such assets are accounted for and how impairment of such assets is assessed and recognized. </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LongLivedAssetsPolicyPolicyTextBlock" xlink:href="efoi-20201231.xsd#efoi_LongLivedAssetsPolicyPolicyTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LongLivedAssetsPolicyPolicyTextBlock" xlink:to="lab_efoi_LongLivedAssetsPolicyPolicyTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths_938df7c5-aeeb-49c4-8193-8f96bea6f7b8_terseLabel_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2021 </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths_label_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due Next Rolling Twelve Months </link:label>
<link:label id="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths_documentation_en-US" xlink:label="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructured Leases, Lessee, Operating Lease, Liability, Payments, Due Next Rolling Twelve Months </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:href="efoi-20201231.xsd#efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:to="lab_efoi_RestructuredLeasesLesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SupplementalCashFlowInformationAbstract_3965370c-d3a2-4d7c-96d9-9c5f1fad4dfa_terseLabel_en-US" xlink:label="lab_us-gaap_SupplementalCashFlowInformationAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Supplemental information: </link:label>
<link:label id="lab_us-gaap_SupplementalCashFlowInformationAbstract_label_en-US" xlink:label="lab_us-gaap_SupplementalCashFlowInformationAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Supplemental Cash Flow Information [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract" xlink:to="lab_us-gaap_SupplementalCashFlowInformationAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest_feab84fa-1f64-4048-9d55-460e12387f80_terseLabel_en-US" xlink:label="lab_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ownership interest </link:label>
<link:label id="lab_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest_label_en-US" xlink:label="lab_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest" xlink:to="lab_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_PaymentProtectionProgramCurrent_17db4553-9125-4390-8b16-078984d6daa8_terseLabel_en-US" xlink:label="lab_efoi_PaymentProtectionProgramCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> PPP loan </link:label>
<link:label id="lab_efoi_PaymentProtectionProgramCurrent_label_en-US" xlink:label="lab_efoi_PaymentProtectionProgramCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payment Protection Program, Current </link:label>
<link:label id="lab_efoi_PaymentProtectionProgramCurrent_documentation_en-US" xlink:label="lab_efoi_PaymentProtectionProgramCurrent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payment Protection Program, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_PaymentProtectionProgramCurrent" xlink:href="efoi-20201231.xsd#efoi_PaymentProtectionProgramCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_PaymentProtectionProgramCurrent" xlink:to="lab_efoi_PaymentProtectionProgramCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_b6b48678-0806-400c-939e-495b516a25b3_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Issuance of common stock under employee stock option and stock purchase plans (in shares) </link:label>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Issued During Period, Shares, Employee Stock Purchase Plans </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityFilerCategory_74a18d28-1b12-41ed-84aa-9768a899a3e1_terseLabel_en-US" xlink:label="lab_dei_EntityFilerCategory" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Filer Category </link:label>
<link:label id="lab_dei_EntityFilerCategory_label_en-US" xlink:label="lab_dei_EntityFilerCategory" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Filer Category </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityFilerCategory"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityFilerCategory" xlink:to="lab_dei_EntityFilerCategory" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock_a5b9db3e-ff8f-4ea3-9fdc-3cb9b38ce179_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary of Impact of Results of Stock-Based Compensation </link:label>
<link:label id="lab_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:to="lab_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CommonStockMember_7ee064aa-8966-4c2c-aa0b-8f4ea485f0b3_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock </link:label>
<link:label id="lab_us-gaap_CommonStockMember_label_en-US" xlink:label="lab_us-gaap_CommonStockMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockMember" xlink:to="lab_us-gaap_CommonStockMember" xlink:type="arc" order="1"/>
<link:label id="lab_srt_ProductsAndServicesDomain_868c9be7-5fa4-440b-b974-5c6401e09d87_terseLabel_en-US" xlink:label="lab_srt_ProductsAndServicesDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product and Service [Domain] </link:label>
<link:label id="lab_srt_ProductsAndServicesDomain_label_en-US" xlink:label="lab_srt_ProductsAndServicesDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product and Service [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ProductsAndServicesDomain" xlink:to="lab_srt_ProductsAndServicesDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentLineItems_1c92dd94-39fc-490b-9261-2bff8e917e07_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Line Items] </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentLineItems_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Line Items] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain_3d064f8b-a8e9-46d6-9a6e-b3b67e297776_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment, Type [Domain] </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Lived Tangible Asset [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeOperatingLeaseDiscountRate_c8dd0ab3-cd4f-45bc-818e-4ab0c1c0d1bb_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseDiscountRate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease, discount rate </link:label>
<link:label id="lab_us-gaap_LesseeOperatingLeaseDiscountRate_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseDiscountRate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Discount Rate </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseDiscountRate" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseDiscountRate"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseDiscountRate" xlink:to="lab_us-gaap_LesseeOperatingLeaseDiscountRate" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ConcentrationRiskBenchmarkDomain_7b592148-f6be-4963-8112-ac193eadfda8_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Benchmark [Domain] </link:label>
<link:label id="lab_us-gaap_ConcentrationRiskBenchmarkDomain_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Benchmark [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="lab_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AllowanceForCreditLossMember_b51a832a-5f94-4cac-94d5-377aa9313478_terseLabel_en-US" xlink:label="lab_us-gaap_AllowanceForCreditLossMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Allowance for doubtful accounts and returns </link:label>
<link:label id="lab_us-gaap_AllowanceForCreditLossMember_label_en-US" xlink:label="lab_us-gaap_AllowanceForCreditLossMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Allowance, Credit Loss [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForCreditLossMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllowanceForCreditLossMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AllowanceForCreditLossMember" xlink:to="lab_us-gaap_AllowanceForCreditLossMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFour_66ca2b91-01f4-4b08-bb49-62a10ad559a3_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFour" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2024 </link:label>
<link:label id="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFour_label_en-US" xlink:label="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFour" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessor, Operating Lease, Payments to be Received, Rolling Year Four </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFour" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFour"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFour" xlink:to="lab_us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearFour" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ConvertibleDebtMember_a12bbe8d-6854-480e-8676-5756ff074497_terseLabel_en-US" xlink:label="lab_us-gaap_ConvertibleDebtMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Convertible Debt </link:label>
<link:label id="lab_us-gaap_ConvertibleDebtMember_label_en-US" xlink:label="lab_us-gaap_ConvertibleDebtMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Convertible Debt [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConvertibleDebtMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConvertibleDebtMember" xlink:to="lab_us-gaap_ConvertibleDebtMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentTextBlock_0254a580-3375-4916-8647-082eed8e8b63_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Property and Equipment </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentTextBlock_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesNewIssues_808459e1-544d-4ff7-9edf-55b5b629eddb_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Shares issued (in shares) </link:label>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesNewIssues_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Issued During Period, Shares, New Issues </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityMinimumRequirement_26d12f0e-f97f-42ad-ae8a-883c723019e2_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityMinimumRequirement" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Minimum borrowing requirement </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityMinimumRequirement_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityMinimumRequirement" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Minimum Requirement </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityMinimumRequirement_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityMinimumRequirement" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Minimum Requirement </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityMinimumRequirement" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityMinimumRequirement"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityMinimumRequirement" xlink:to="lab_efoi_LineOfCreditFacilityMinimumRequirement" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LeaseholdImprovementsMember_b2f37e88-27f7-4fdf-b21b-d293aa299db9_terseLabel_en-US" xlink:label="lab_us-gaap_LeaseholdImprovementsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leasehold improvements </link:label>
<link:label id="lab_us-gaap_LeaseholdImprovementsMember_label_en-US" xlink:label="lab_us-gaap_LeaseholdImprovementsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leasehold Improvements [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseholdImprovementsMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeaseholdImprovementsMember" xlink:to="lab_us-gaap_LeaseholdImprovementsMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SalesRevenueNetMember_b2a31afb-5fe4-415b-849e-e4c29e96cad3_terseLabel_en-US" xlink:label="lab_us-gaap_SalesRevenueNetMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net sales </link:label>
<link:label id="lab_us-gaap_SalesRevenueNetMember_label_en-US" xlink:label="lab_us-gaap_SalesRevenueNetMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue Benchmark [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SalesRevenueNetMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SalesRevenueNetMember" xlink:to="lab_us-gaap_SalesRevenueNetMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_OffshoreSupplierMember_5d0fb5a7-c4a6-4b81-aecd-d03bc070a66f_terseLabel_en-US" xlink:label="lab_efoi_OffshoreSupplierMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Offshore Supplier </link:label>
<link:label id="lab_efoi_OffshoreSupplierMember_label_en-US" xlink:label="lab_efoi_OffshoreSupplierMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Offshore Supplier [Member] </link:label>
<link:label id="lab_efoi_OffshoreSupplierMember_documentation_en-US" xlink:label="lab_efoi_OffshoreSupplierMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Offshore Supplier </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_OffshoreSupplierMember" xlink:href="efoi-20201231.xsd#efoi_OffshoreSupplierMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_OffshoreSupplierMember" xlink:to="lab_efoi_OffshoreSupplierMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_230ea4bc-ce3d-477a-b15f-9546e1ce98e0_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stated interest rate </link:label>
<link:label id="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Interest Rate, Stated Percentage </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:to="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_9fce2d5b-328b-464a-b095-9c1bcc1b99e8_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Conversion of convertible securities </link:label>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Issued During Period, Shares, Conversion of Convertible Securities </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour_54b9703a-356c-4a7f-b6f3-7b4630683a0c_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2024 </link:label>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Four </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProvisionForDoubtfulAccounts_8026f393-507b-4104-816f-416f713a51aa_terseLabel_en-US" xlink:label="lab_us-gaap_ProvisionForDoubtfulAccounts" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Provision for doubtful accounts receivable </link:label>
<link:label id="lab_us-gaap_ProvisionForDoubtfulAccounts_label_en-US" xlink:label="lab_us-gaap_ProvisionForDoubtfulAccounts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, Credit Loss Expense (Reversal) </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProvisionForDoubtfulAccounts" xlink:to="lab_us-gaap_ProvisionForDoubtfulAccounts" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_WriteOffOfDeferredDebtIssuanceCost_fdf17043-083f-4b31-9d5a-4d9a0fc7b28a_terseLabel_en-US" xlink:label="lab_us-gaap_WriteOffOfDeferredDebtIssuanceCost" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Write off of remaining related debt and acquisition cost </link:label>
<link:label id="lab_us-gaap_WriteOffOfDeferredDebtIssuanceCost_label_en-US" xlink:label="lab_us-gaap_WriteOffOfDeferredDebtIssuanceCost" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Write off of Deferred Debt Issuance Cost </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WriteOffOfDeferredDebtIssuanceCost"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost" xlink:to="lab_us-gaap_WriteOffOfDeferredDebtIssuanceCost" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ProductWarrantyLiabilityTable_1aa76862-4a5c-4804-96eb-f8b0c2ab4983_terseLabel_en-US" xlink:label="lab_us-gaap_ProductWarrantyLiabilityTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product Warranty Liability [Table] </link:label>
<link:label id="lab_us-gaap_ProductWarrantyLiabilityTable_label_en-US" xlink:label="lab_us-gaap_ProductWarrantyLiabilityTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product Warranty Liability [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductWarrantyLiabilityTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProductWarrantyLiabilityTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProductWarrantyLiabilityTable" xlink:to="lab_us-gaap_ProductWarrantyLiabilityTable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_7ff2a25b-ac77-493d-b25b-78961e64146a_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercised (in shares) </link:label>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_050a39d2-e45f-4616-822a-5ac3c9723299_negatedLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercised (in shares) </link:label>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock_f8ce1c5e-67b9-4da8-b38b-a94c142119b0_terseLabel_en-US" xlink:label="lab_efoi_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Supplemental Cash Flow Information Related To Leases </link:label>
<link:label id="lab_efoi_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock_label_en-US" xlink:label="lab_efoi_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Supplemental Cash Flow Information Related To Leases [Table Text Block] </link:label>
<link:label id="lab_efoi_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock_documentation_en-US" xlink:label="lab_efoi_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> [Table Text Block] for Supplemental Cash Flow Information Related To Leases [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock" xlink:href="efoi-20201231.xsd#efoi_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock" xlink:to="lab_efoi_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RelatedPartyTransactionsAbstract_58322f5e-8de5-4740-be14-182769e3e806_terseLabel_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party Transactions [Abstract] </link:label>
<link:label id="lab_us-gaap_RelatedPartyTransactionsAbstract_label_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party Transactions [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RelatedPartyTransactionsAbstract" xlink:to="lab_us-gaap_RelatedPartyTransactionsAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_f0605e96-2bfb-4d2d-ab54-ce2e4b605f8e_totalLabel_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net increase (decrease) in cash and restricted cash </link:label>
<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_label_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAsset_e56947f3-736e-4c46-9d5a-21141150b4b3_totalLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance lease assets, net </link:label>
<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAsset_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-of-Use Asset, after Accumulated Amortization </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAsset" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAsset"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseRightOfUseAsset" xlink:to="lab_us-gaap_FinanceLeaseRightOfUseAsset" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_c5a3ae30-f6c2-4e9c-9b17-19e14270a28a_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Future Maturities of Operating Lease Liabilities </link:label>
<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, Maturity [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EmployeeStockOptionMember_f7b8cd36-f985-4bd8-a2ca-a13377de10ac_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeStockOptionMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employee stock option </link:label>
<link:label id="lab_us-gaap_EmployeeStockOptionMember_label_en-US" xlink:label="lab_us-gaap_EmployeeStockOptionMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeStockOptionMember" xlink:to="lab_us-gaap_EmployeeStockOptionMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_BasisOfAccountingPolicyPolicyTextBlock_ba30d188-d443-4df9-b93b-bc026c716ffd_terseLabel_en-US" xlink:label="lab_us-gaap_BasisOfAccountingPolicyPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Basis of presentation </link:label>
<link:label id="lab_us-gaap_BasisOfAccountingPolicyPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_BasisOfAccountingPolicyPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Basis of Accounting, Policy [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BasisOfAccountingPolicyPolicyTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BasisOfAccountingPolicyPolicyTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BasisOfAccountingPolicyPolicyTextBlock" xlink:to="lab_us-gaap_BasisOfAccountingPolicyPolicyTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityAnnualFacilityFeePeriod_f2bc333a-afaf-463a-bc4f-8b54760af866_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAnnualFacilityFeePeriod" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Annual facility period </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAnnualFacilityFeePeriod_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAnnualFacilityFeePeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Annual Facility Fee, Period </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityAnnualFacilityFeePeriod_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityAnnualFacilityFeePeriod" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Annual Facility Fee, Period </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityAnnualFacilityFeePeriod" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityAnnualFacilityFeePeriod"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityAnnualFacilityFeePeriod" xlink:to="lab_efoi_LineOfCreditFacilityAnnualFacilityFeePeriod" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_cb46bb4f-fde7-4669-9778-d61c4eb3e710_terseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Basic (in shares) </link:label>
<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_label_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Number of Shares Outstanding, Basic </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:to="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_Plan2020Member_26d012f5-84aa-44f6-b807-4ab5d00e56ec_terseLabel_en-US" xlink:label="lab_efoi_Plan2020Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2020 Plan </link:label>
<link:label id="lab_efoi_Plan2020Member_label_en-US" xlink:label="lab_efoi_Plan2020Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Plan 2020 [Member] </link:label>
<link:label id="lab_efoi_Plan2020Member_documentation_en-US" xlink:label="lab_efoi_Plan2020Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Plan 2020 </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_Plan2020Member" xlink:href="efoi-20201231.xsd#efoi_Plan2020Member"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_Plan2020Member" xlink:to="lab_efoi_Plan2020Member" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_0389dd89-8273-4efe-86d9-c9798bc0a663_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Risk-free interest rate </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SubsequentEventsAbstract_2e5491b0-5105-436c-9357-c239e0e21e79_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Events [Abstract] </link:label>
<link:label id="lab_us-gaap_SubsequentEventsAbstract_label_en-US" xlink:label="lab_us-gaap_SubsequentEventsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Events [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventsAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventsAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventsAbstract" xlink:to="lab_us-gaap_SubsequentEventsAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_srt_OwnershipAxis_9ec7c599-f210-46d5-ad49-fb331060520b_terseLabel_en-US" xlink:label="lab_srt_OwnershipAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ownership [Axis] </link:label>
<link:label id="lab_srt_OwnershipAxis_label_en-US" xlink:label="lab_srt_OwnershipAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ownership [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OwnershipAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_OwnershipAxis" xlink:to="lab_srt_OwnershipAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_849a514e-d05d-42b5-8310-f9d6dc6d80d8_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Canceled (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RestructuringReserveCurrent_be48b8d9-3f84-40ce-8615-bc6dcb36d7d5_terseLabel_en-US" xlink:label="lab_us-gaap_RestructuringReserveCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued restructuring </link:label>
<link:label id="lab_us-gaap_RestructuringReserveCurrent_9a7aed19-c5f5-4e65-bef8-0d0f718757ba_verboseLabel_en-US" xlink:label="lab_us-gaap_RestructuringReserveCurrent" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less, short-term restructuring liability </link:label>
<link:label id="lab_us-gaap_RestructuringReserveCurrent_label_en-US" xlink:label="lab_us-gaap_RestructuringReserveCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Reserve, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestructuringReserveCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringReserveCurrent" xlink:to="lab_us-gaap_RestructuringReserveCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_NotePurchaseAgreementMember_d7b3197f-2763-4cc2-8e24-d368ea24ede9_terseLabel_en-US" xlink:label="lab_efoi_NotePurchaseAgreementMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Note Purchase Agreement </link:label>
<link:label id="lab_efoi_NotePurchaseAgreementMember_label_en-US" xlink:label="lab_efoi_NotePurchaseAgreementMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Note Purchase Agreement [Member] </link:label>
<link:label id="lab_efoi_NotePurchaseAgreementMember_documentation_en-US" xlink:label="lab_efoi_NotePurchaseAgreementMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Note Purchase Agreement [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_NotePurchaseAgreementMember" xlink:href="efoi-20201231.xsd#efoi_NotePurchaseAgreementMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_NotePurchaseAgreementMember" xlink:to="lab_efoi_NotePurchaseAgreementMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SaleOfStockNameOfTransactionDomain_f10209e2-0f95-41e1-9786-dcf2c0cc055d_terseLabel_en-US" xlink:label="lab_us-gaap_SaleOfStockNameOfTransactionDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Sale of Stock [Domain] </link:label>
<link:label id="lab_us-gaap_SaleOfStockNameOfTransactionDomain_label_en-US" xlink:label="lab_us-gaap_SaleOfStockNameOfTransactionDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Sale of Stock [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="lab_us-gaap_SaleOfStockNameOfTransactionDomain" xlink:type="arc" order="1"/>
<link:label id="lab_srt_OwnershipDomain_f59914f7-0120-4265-ae6e-93d0fff1204e_terseLabel_en-US" xlink:label="lab_srt_OwnershipDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ownership [Domain] </link:label>
<link:label id="lab_srt_OwnershipDomain_label_en-US" xlink:label="lab_srt_OwnershipDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ownership [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OwnershipDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_OwnershipDomain" xlink:to="lab_srt_OwnershipDomain" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PlanNameDomain_4dac37da-fa4f-4b09-a7a0-fa8271464488_terseLabel_en-US" xlink:label="lab_us-gaap_PlanNameDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Plan Name [Domain] </link:label>
<link:label id="lab_us-gaap_PlanNameDomain_label_en-US" xlink:label="lab_us-gaap_PlanNameDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Plan Name [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PlanNameDomain" xlink:to="lab_us-gaap_PlanNameDomain" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityWellKnownSeasonedIssuer_f303d8a8-2d48-41f5-9d45-137a9415ed85_terseLabel_en-US" xlink:label="lab_dei_EntityWellKnownSeasonedIssuer" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Well-known Seasoned Issuer </link:label>
<link:label id="lab_dei_EntityWellKnownSeasonedIssuer_label_en-US" xlink:label="lab_dei_EntityWellKnownSeasonedIssuer" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Well-known Seasoned Issuer </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityWellKnownSeasonedIssuer" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityWellKnownSeasonedIssuer"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityWellKnownSeasonedIssuer" xlink:to="lab_dei_EntityWellKnownSeasonedIssuer" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_InterestPaidNet_e7bbae49-5250-4c8b-89c9-31d8ea166534_terseLabel_en-US" xlink:label="lab_us-gaap_InterestPaidNet" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash paid in year for interest </link:label>
<link:label id="lab_us-gaap_InterestPaidNet_label_en-US" xlink:label="lab_us-gaap_InterestPaidNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest Paid, Excluding Capitalized Interest, Operating Activities </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestPaidNet"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestPaidNet" xlink:to="lab_us-gaap_InterestPaidNet" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_YehMeiChengMember_d75f9267-c357-4643-aa74-65909432cb27_terseLabel_en-US" xlink:label="lab_efoi_YehMeiChengMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Yeh-Mei Cheng </link:label>
<link:label id="lab_efoi_YehMeiChengMember_label_en-US" xlink:label="lab_efoi_YehMeiChengMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Yeh Mei Cheng [Member] </link:label>
<link:label id="lab_efoi_YehMeiChengMember_documentation_en-US" xlink:label="lab_efoi_YehMeiChengMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Yeh-Mei Cheng </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_YehMeiChengMember" xlink:href="efoi-20201231.xsd#efoi_YehMeiChengMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_YehMeiChengMember" xlink:to="lab_efoi_YehMeiChengMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryCostsPercent_2f6715df-f2b9-43df-9d21-fd4ae6149a37_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryCostsPercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory costs </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryCostsPercent_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryCostsPercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Borrowing Capacity, Inventory Costs, Percent </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryCostsPercent_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryCostsPercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Borrowing Capacity, Inventory Costs, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityBorrowingCapacityInventoryCostsPercent" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityBorrowingCapacityInventoryCostsPercent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityBorrowingCapacityInventoryCostsPercent" xlink:to="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryCostsPercent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockOptionMember_6d7054d1-3131-4656-9e44-bc2ec131b4ee_terseLabel_en-US" xlink:label="lab_us-gaap_StockOptionMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Option </link:label>
<link:label id="lab_us-gaap_StockOptionMember_label_en-US" xlink:label="lab_us-gaap_StockOptionMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Option [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockOptionMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockOptionMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockOptionMember" xlink:to="lab_us-gaap_StockOptionMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LeaseSupplementalBalanceSheetInformationTableTextBlock_ec2a0402-828d-46da-9743-c19ca7957f5f_terseLabel_en-US" xlink:label="lab_efoi_LeaseSupplementalBalanceSheetInformationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Supplemental Balance Sheet Information </link:label>
<link:label id="lab_efoi_LeaseSupplementalBalanceSheetInformationTableTextBlock_label_en-US" xlink:label="lab_efoi_LeaseSupplementalBalanceSheetInformationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease, Supplemental Balance Sheet Information [Table Text Block] </link:label>
<link:label id="lab_efoi_LeaseSupplementalBalanceSheetInformationTableTextBlock_documentation_en-US" xlink:label="lab_efoi_LeaseSupplementalBalanceSheetInformationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease, Supplemental Balance Sheet Information [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LeaseSupplementalBalanceSheetInformationTableTextBlock" xlink:href="efoi-20201231.xsd#efoi_LeaseSupplementalBalanceSheetInformationTableTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LeaseSupplementalBalanceSheetInformationTableTextBlock" xlink:to="lab_efoi_LeaseSupplementalBalanceSheetInformationTableTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock_325df545-2687-4d90-a34e-ee9905a6580e_terseLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and restricted cash </link:label>
<link:label id="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents, Policy [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsPolicyTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:to="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_Revenues_275b3555-e463-4416-bf6e-468d2dbe70e8_terseLabel_en-US" xlink:label="lab_us-gaap_Revenues" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net sales </link:label>
<link:label id="lab_us-gaap_Revenues_daba228f-1ea1-4e5f-81a8-0a6db7dbb6a6_verboseLabel_en-US" xlink:label="lab_us-gaap_Revenues" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net sales </link:label>
<link:label id="lab_us-gaap_Revenues_label_en-US" xlink:label="lab_us-gaap_Revenues" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenues </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Revenues"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Revenues" xlink:to="lab_us-gaap_Revenues" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StatementClassOfStockAxis_3fd3fee2-ecbf-466d-a896-1132a3e32910_terseLabel_en-US" xlink:label="lab_us-gaap_StatementClassOfStockAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Stock [Axis] </link:label>
<link:label id="lab_us-gaap_StatementClassOfStockAxis_label_en-US" xlink:label="lab_us-gaap_StatementClassOfStockAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Stock [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementClassOfStockAxis" xlink:to="lab_us-gaap_StatementClassOfStockAxis" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_ProceedsFromTheIssuanceOfCommonStockAndWarrantsNetOfIssuanceCosts_3b6244c4-382e-41b7-90ab-2174aa55f19e_terseLabel_en-US" xlink:label="lab_efoi_ProceedsFromTheIssuanceOfCommonStockAndWarrantsNetOfIssuanceCosts" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net proceeds from sale of common stock </link:label>
<link:label id="lab_efoi_ProceedsFromTheIssuanceOfCommonStockAndWarrantsNetOfIssuanceCosts_label_en-US" xlink:label="lab_efoi_ProceedsFromTheIssuanceOfCommonStockAndWarrantsNetOfIssuanceCosts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from the Issuance of Common Stock and Warrants, Net of Issuance Costs </link:label>
<link:label id="lab_efoi_ProceedsFromTheIssuanceOfCommonStockAndWarrantsNetOfIssuanceCosts_documentation_en-US" xlink:label="lab_efoi_ProceedsFromTheIssuanceOfCommonStockAndWarrantsNetOfIssuanceCosts" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from the Issuance of Common Stock and Warrants, Net of Issuance Costs </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_ProceedsFromTheIssuanceOfCommonStockAndWarrantsNetOfIssuanceCosts" xlink:href="efoi-20201231.xsd#efoi_ProceedsFromTheIssuanceOfCommonStockAndWarrantsNetOfIssuanceCosts"/>
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<link:label id="lab_us-gaap_InventoryPolicyTextBlock_79c0702e-c696-46d0-b988-fbfec8f4a1d3_terseLabel_en-US" xlink:label="lab_us-gaap_InventoryPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventories </link:label>
<link:label id="lab_us-gaap_InventoryPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_InventoryPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory, Policy [Policy Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryPolicyTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryPolicyTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InventoryPolicyTextBlock" xlink:to="lab_us-gaap_InventoryPolicyTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_IncomeTaxExpenseBenefit_178fc07a-c6ac-4a16-9bc5-713a467c6b0b_verboseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> (Benefit from) provision for income taxes </link:label>
<link:label id="lab_us-gaap_IncomeTaxExpenseBenefit_e664da32-f5b6-406e-8826-922c420dc2a1_totalLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> (Benefit from) provision for income taxes </link:label>
<link:label id="lab_us-gaap_IncomeTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Expense (Benefit) </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_IncomeTaxExpenseBenefit" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_95346840-bffe-4a41-b646-4301f9e05969_periodStartLabel_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and restricted cash, beginning of year </link:label>
<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_255cc5a2-9a44-4a20-96d7-12cb56b605bf_periodEndLabel_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and restricted cash, end of year </link:label>
<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_a7065c1f-a8ca-4879-8f87-0ae1132d2145_totalLabel_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and restricted cash </link:label>
<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_ad5b89db-29b0-481d-bfcc-7228edf6ffd7_terseLabel_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and cash equivalents </link:label>
<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_label_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:to="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_4d0b4853-fae0-410a-8bd9-182855cce382_terseLabel_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Standards Update and Change in Accounting Principle [Table] </link:label>
<link:label id="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_label_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Standards Update and Change in Accounting Principle [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:to="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AccruedLiabilitiesCurrent_4b9a2c9d-7759-4abf-95b3-c0dfcfbf9f37_totalLabel_en-US" xlink:label="lab_us-gaap_AccruedLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total accrued liabilities </link:label>
<link:label id="lab_us-gaap_AccruedLiabilitiesCurrent_label_en-US" xlink:label="lab_us-gaap_AccruedLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued Liabilities, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccruedLiabilitiesCurrent" xlink:to="lab_us-gaap_AccruedLiabilitiesCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EarningsPerShareDiluted_d94b0265-1e65-4342-8ca3-e12f4ecb9f7c_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareDiluted" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net loss per share, diluted (in dollars per share) </link:label>
<link:label id="lab_us-gaap_EarningsPerShareDiluted_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareDiluted" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share, Diluted </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareDiluted"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareDiluted" xlink:to="lab_us-gaap_EarningsPerShareDiluted" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityCurrent_b4c2da24-e271-416b-a60b-c8dac455b9da_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance lease liabilities </link:label>
<link:label id="lab_us-gaap_FinanceLeaseLiabilityCurrent_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Current </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityCurrent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityCurrent" xlink:to="lab_us-gaap_FinanceLeaseLiabilityCurrent" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_RelatedPartyTransactionsOwnershipinReportingEntitybyRelatedParty_af94e5f8-163c-4872-a823-fcfc828ca94f_terseLabel_en-US" xlink:label="lab_efoi_RelatedPartyTransactionsOwnershipinReportingEntitybyRelatedParty" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ownership in reporting entity by related party </link:label>
<link:label id="lab_efoi_RelatedPartyTransactionsOwnershipinReportingEntitybyRelatedParty_label_en-US" xlink:label="lab_efoi_RelatedPartyTransactionsOwnershipinReportingEntitybyRelatedParty" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party Transactions, Ownership in Reporting Entity by Related Party </link:label>
<link:label id="lab_efoi_RelatedPartyTransactionsOwnershipinReportingEntitybyRelatedParty_documentation_en-US" xlink:label="lab_efoi_RelatedPartyTransactionsOwnershipinReportingEntitybyRelatedParty" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party Transactions, Ownership in Reporting Entity by Related Party </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_RelatedPartyTransactionsOwnershipinReportingEntitybyRelatedParty" xlink:href="efoi-20201231.xsd#efoi_RelatedPartyTransactionsOwnershipinReportingEntitybyRelatedParty"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_RelatedPartyTransactionsOwnershipinReportingEntitybyRelatedParty" xlink:to="lab_efoi_RelatedPartyTransactionsOwnershipinReportingEntitybyRelatedParty" xlink:type="arc" order="1"/>
<link:label id="lab_dei_LocalPhoneNumber_bf528912-ce2a-4930-9e21-dfa5013f7d64_terseLabel_en-US" xlink:label="lab_dei_LocalPhoneNumber" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Local Phone Number </link:label>
<link:label id="lab_dei_LocalPhoneNumber_label_en-US" xlink:label="lab_dei_LocalPhoneNumber" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Local Phone Number </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LocalPhoneNumber"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_LocalPhoneNumber" xlink:to="lab_dei_LocalPhoneNumber" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_CreditFacilitiesMember_4587022f-e2d1-494b-842d-2f8c4c3fee12_terseLabel_en-US" xlink:label="lab_efoi_CreditFacilitiesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Facilities </link:label>
<link:label id="lab_efoi_CreditFacilitiesMember_label_en-US" xlink:label="lab_efoi_CreditFacilitiesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Facilities [Member] </link:label>
<link:label id="lab_efoi_CreditFacilitiesMember_documentation_en-US" xlink:label="lab_efoi_CreditFacilitiesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Facilities </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_CreditFacilitiesMember" xlink:href="efoi-20201231.xsd#efoi_CreditFacilitiesMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_CreditFacilitiesMember" xlink:to="lab_efoi_CreditFacilitiesMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration_59531d12-bb78-4a97-860d-d1eca7039c97_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating loss, subject to expiration </link:label>
<link:label id="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" xlink:to="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" xlink:type="arc" order="1"/>
<link:label id="lab_srt_CumulativeEffectPeriodOfAdoptionDomain_c25c3ca9-1931-45e8-8163-94e28fd0acf6_terseLabel_en-US" xlink:label="lab_srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cumulative Effect, Period of Adoption [Domain] </link:label>
<link:label id="lab_srt_CumulativeEffectPeriodOfAdoptionDomain_label_en-US" xlink:label="lab_srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cumulative Effect, Period of Adoption [Domain] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:to="lab_srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_AustinFacilityMember_f1880ecb-01dd-4b6f-af28-779ed3898e58_terseLabel_en-US" xlink:label="lab_efoi_AustinFacilityMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Austin Facility </link:label>
<link:label id="lab_efoi_AustinFacilityMember_label_en-US" xlink:label="lab_efoi_AustinFacilityMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Austin Facility [Member] </link:label>
<link:label id="lab_efoi_AustinFacilityMember_documentation_en-US" xlink:label="lab_efoi_AustinFacilityMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Austin Facility </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_AustinFacilityMember" xlink:href="efoi-20201231.xsd#efoi_AustinFacilityMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_AustinFacilityMember" xlink:to="lab_efoi_AustinFacilityMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ScheduleOfStockByClassTable_86a85fe2-96e3-4ec1-9594-cae51e2072ec_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfStockByClassTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Stock by Class [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfStockByClassTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfStockByClassTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Stock by Class [Table] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable" xlink:to="lab_us-gaap_ScheduleOfStockByClassTable" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_e5314d3c-c10c-4fc6-9694-87e2d422368f_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Options exercised, intrinsic value </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_7c93ee52-b035-4e70-b049-34f76e71a8ba_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Level 3 Fair Value Reconciliation </link:label>
<link:label id="lab_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_label_en-US" xlink:label="lab_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:to="lab_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_a0806801-9326-41e3-9b3e-08753060015b_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Range of Exercise Prices, upper limit (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:to="lab_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_cf48acda-e717-43a1-9c4d-e05f36eca5ee_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] </link:label>
<link:label id="lab_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_label_en-US" xlink:label="lab_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:to="lab_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtInstrumentCarryingAmount_86471293-5658-4047-ab92-5998b964c376_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentCarryingAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total liability </link:label>
<link:label id="lab_us-gaap_DebtInstrumentCarryingAmount_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentCarryingAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term Debt, Gross </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentCarryingAmount" xlink:to="lab_us-gaap_DebtInstrumentCarryingAmount" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresByPlanAxis_bcd2f7ab-c9d8-4aae-bc5b-6e4463ea03d7_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresByPlanAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employee Stock Ownership Plan (ESOP) Name [Axis] </link:label>
<link:label id="lab_us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresByPlanAxis_label_en-US" xlink:label="lab_us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresByPlanAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employee Stock Ownership Plan (ESOP) Name [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresByPlanAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresByPlanAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresByPlanAxis" xlink:to="lab_us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresByPlanAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_Depreciation_9cab1467-0042-400c-949f-b0bf672e6751_terseLabel_en-US" xlink:label="lab_us-gaap_Depreciation" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Depreciation </link:label>
<link:label id="lab_us-gaap_Depreciation_label_en-US" xlink:label="lab_us-gaap_Depreciation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Depreciation </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Depreciation"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Depreciation" xlink:to="lab_us-gaap_Depreciation" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityAddressAddressLine1_df308618-74bb-4435-b787-edd3031177e5_terseLabel_en-US" xlink:label="lab_dei_EntityAddressAddressLine1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, Address Line One </link:label>
<link:label id="lab_dei_EntityAddressAddressLine1_label_en-US" xlink:label="lab_dei_EntityAddressAddressLine1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, Address Line One </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressAddressLine1"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityAddressAddressLine1" xlink:to="lab_dei_EntityAddressAddressLine1" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityAddressAddressLine2_caeaa1f1-ae32-4f95-a6d9-ef4281de91fe_terseLabel_en-US" xlink:label="lab_dei_EntityAddressAddressLine2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, Address Line Two </link:label>
<link:label id="lab_dei_EntityAddressAddressLine2_label_en-US" xlink:label="lab_dei_EntityAddressAddressLine2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, Address Line Two </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine2" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressAddressLine2"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityAddressAddressLine2" xlink:to="lab_dei_EntityAddressAddressLine2" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PrimeRateMember_02c222db-fc0b-434e-8767-b055d9dcdef7_terseLabel_en-US" xlink:label="lab_us-gaap_PrimeRateMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prime Rate </link:label>
<link:label id="lab_us-gaap_PrimeRateMember_label_en-US" xlink:label="lab_us-gaap_PrimeRateMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prime Rate [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrimeRateMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrimeRateMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PrimeRateMember" xlink:to="lab_us-gaap_PrimeRateMember" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityEmergingGrowthCompany_8e1d725e-61a6-42bb-852d-c52ef3f6791a_terseLabel_en-US" xlink:label="lab_dei_EntityEmergingGrowthCompany" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Emerging Growth Company </link:label>
<link:label id="lab_dei_EntityEmergingGrowthCompany_label_en-US" xlink:label="lab_dei_EntityEmergingGrowthCompany" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Emerging Growth Company </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityEmergingGrowthCompany"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityEmergingGrowthCompany" xlink:to="lab_dei_EntityEmergingGrowthCompany" xlink:type="arc" order="1"/>
<link:label id="lab_srt_ScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock_7b351202-dc16-4571-9718-4ef038abfa91_terseLabel_en-US" xlink:label="lab_srt_ScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule II - Schedule of Valuation and Qualifying Accounts </link:label>
<link:label id="lab_srt_ScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock_label_en-US" xlink:label="lab_srt_ScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock" xlink:to="lab_srt_ScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ConvertiblePreferredStockMember_de85d333-47ff-4a62-a6a5-43ba9e3d0a67_terseLabel_en-US" xlink:label="lab_us-gaap_ConvertiblePreferredStockMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Convertible Preferred Stock </link:label>
<link:label id="lab_us-gaap_ConvertiblePreferredStockMember_label_en-US" xlink:label="lab_us-gaap_ConvertiblePreferredStockMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Convertible Preferred Stock [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertiblePreferredStockMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConvertiblePreferredStockMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConvertiblePreferredStockMember" xlink:to="lab_us-gaap_ConvertiblePreferredStockMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_3c414a33-8b65-4dd9-8aea-a358e36710b4_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit facility, maximum borrowing capacity </link:label>
<link:label id="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Maximum Borrowing Capacity </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:to="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_DistributorToTheU.S.NavyMember_edbb399a-6c28-48f2-9e1c-d1a8b69b656a_terseLabel_en-US" xlink:label="lab_efoi_DistributorToTheU.S.NavyMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Distributor To The U.S. Navy </link:label>
<link:label id="lab_efoi_DistributorToTheU.S.NavyMember_label_en-US" xlink:label="lab_efoi_DistributorToTheU.S.NavyMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Distributor To The U.S. Navy [Member] </link:label>
<link:label id="lab_efoi_DistributorToTheU.S.NavyMember_documentation_en-US" xlink:label="lab_efoi_DistributorToTheU.S.NavyMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Distributor To The U.S. Navy [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_DistributorToTheU.S.NavyMember" xlink:href="efoi-20201231.xsd#efoi_DistributorToTheU.S.NavyMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_DistributorToTheU.S.NavyMember" xlink:to="lab_efoi_DistributorToTheU.S.NavyMember" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryValuePercent_89b7fa7b-7285-4f9b-980a-942a416e903a_terseLabel_en-US" xlink:label="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryValuePercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory, net orderly liquidation value </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryValuePercent_label_en-US" xlink:label="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryValuePercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Borrowing Capacity, Inventory Value, Percent </link:label>
<link:label id="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryValuePercent_documentation_en-US" xlink:label="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryValuePercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Borrowing Capacity, Inventory Value, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_LineOfCreditFacilityBorrowingCapacityInventoryValuePercent" xlink:href="efoi-20201231.xsd#efoi_LineOfCreditFacilityBorrowingCapacityInventoryValuePercent"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_LineOfCreditFacilityBorrowingCapacityInventoryValuePercent" xlink:to="lab_efoi_LineOfCreditFacilityBorrowingCapacityInventoryValuePercent" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_AwardTypeAxis_b9df22a3-0238-41b1-b46e-5dc6cdc01bbe_terseLabel_en-US" xlink:label="lab_us-gaap_AwardTypeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Type [Axis] </link:label>
<link:label id="lab_us-gaap_AwardTypeAxis_label_en-US" xlink:label="lab_us-gaap_AwardTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Type [Axis] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AwardTypeAxis" xlink:to="lab_us-gaap_AwardTypeAxis" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_41f12008-9cb4-4610-9258-6a78ece80d0c_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Grant Date Fair Value </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_3c61f2a0-21a5-460a-a25d-e647c2377d51_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Issuance of common stock upon the exercise of warrants </link:label>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised </link:label>
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<link:label id="lab_srt_MaximumMember_2c65c4a1-fd39-4c17-ba92-1cb18f7663bb_terseLabel_en-US" xlink:label="lab_srt_MaximumMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Maximum </link:label>
<link:label id="lab_srt_MaximumMember_label_en-US" xlink:label="lab_srt_MaximumMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Maximum [Member] </link:label>
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<link:label id="lab_us-gaap_PreferredStockSharesAuthorized_589623bf-96fc-4a72-a033-684aee990eda_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockSharesAuthorized" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred stock, shares authorized (in shares) </link:label>
<link:label id="lab_us-gaap_PreferredStockSharesAuthorized_label_en-US" xlink:label="lab_us-gaap_PreferredStockSharesAuthorized" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred Stock, Shares Authorized </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockSharesAuthorized"/>
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<link:label id="lab_us-gaap_RestrictedCash_722f00fe-fa50-4a64-898b-3cf989d28557_terseLabel_en-US" xlink:label="lab_us-gaap_RestrictedCash" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted cash </link:label>
<link:label id="lab_us-gaap_RestrictedCash_label_en-US" xlink:label="lab_us-gaap_RestrictedCash" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted Cash </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCash" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedCash"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestrictedCash" xlink:to="lab_us-gaap_RestrictedCash" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_RetainedEarningsMember_68df64c5-d1ad-4e6e-b73c-bf6b47b8c8e0_terseLabel_en-US" xlink:label="lab_us-gaap_RetainedEarningsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated Deficit </link:label>
<link:label id="lab_us-gaap_RetainedEarningsMember_label_en-US" xlink:label="lab_us-gaap_RetainedEarningsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retained Earnings [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsMember"/>
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<link:label id="lab_us-gaap_PreferredStockSharesOutstanding_3de8f055-272a-4842-915c-12e708736faa_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred stock, shares outstanding </link:label>
<link:label id="lab_us-gaap_PreferredStockSharesOutstanding_label_en-US" xlink:label="lab_us-gaap_PreferredStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Preferred Stock, Shares Outstanding </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockSharesOutstanding"/>
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<link:label id="lab_us-gaap_EffectiveIncomeTaxRateContinuingOperations_5f8ab8dc-630c-49a5-a7c7-dc789c9ac38f_totalLabel_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective income tax rate reconciliation </link:label>
<link:label id="lab_us-gaap_EffectiveIncomeTaxRateContinuingOperations_label_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
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<link:label id="lab_us-gaap_SignificantAccountingPoliciesTextBlock_12eaefa1-e74a-4885-91ca-eb03bffa9a9e_terseLabel_en-US" xlink:label="lab_us-gaap_SignificantAccountingPoliciesTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary of Significant Accounting Policies </link:label>
<link:label id="lab_us-gaap_SignificantAccountingPoliciesTextBlock_label_en-US" xlink:label="lab_us-gaap_SignificantAccountingPoliciesTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Significant Accounting Policies [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SignificantAccountingPoliciesTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SignificantAccountingPoliciesTextBlock"/>
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<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_a1917178-f8e4-4038-9c06-20e3367fa4ea_totalLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net cash used in investing activities </link:label>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Investing Activities </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
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<link:label id="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6382dd53-2c89-479f-9789-7403cb22ca26_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] </link:label>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_370ee0bc-a3cb-4790-afa7-b80cab231b0a_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Type [Domain] </link:label>
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<link:label id="lab_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock_e678d28d-08a7-4f4b-ab02-d569263b98e7_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Restructuring Reserve by Type of Cost </link:label>
<link:label id="lab_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Restructuring Reserve by Type of Cost [Table Text Block] </link:label>
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<link:label id="lab_dei_TradingSymbol_0980258f-5d07-4df2-9f83-921d99c379a8_terseLabel_en-US" xlink:label="lab_dei_TradingSymbol" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Symbol </link:label>
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<link:label id="lab_us-gaap_DeferredTaxAssetsInProcessResearchAndDevelopment_5526b1b5-fb42-43d7-8361-e2ce30cdabe6_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsInProcessResearchAndDevelopment" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tax credits, deferred R&D, and other </link:label>
<link:label id="lab_us-gaap_DeferredTaxAssetsInProcessResearchAndDevelopment_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsInProcessResearchAndDevelopment" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, in Process Research and Development </link:label>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_323ac783-48bc-4468-99a5-a44234481ab2_verboseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercisable (in dollars per share) </link:label>
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<link:label id="lab_efoi_ExercisePriceRangeThreeMember_58725fd5-39cb-4312-9392-771508498a1a_terseLabel_en-US" xlink:label="lab_efoi_ExercisePriceRangeThreeMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise price, range three </link:label>
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<link:label id="lab_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_71f313db-ac3e-4100-ba6d-457e36399f59_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and Equipment </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment Disclosure [Text Block] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StandardProductWarrantyAccrualPayments_b4f8149f-bc79-4d87-9e4d-cb57532bd073_negatedLabel_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyAccrualPayments" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Settlements made during the year (in kind) </link:label>
<link:label id="lab_us-gaap_StandardProductWarrantyAccrualPayments_label_en-US" xlink:label="lab_us-gaap_StandardProductWarrantyAccrualPayments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Standard Product Warranty Accrual, Decrease for Payments </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandardProductWarrantyAccrualPayments" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StandardProductWarrantyAccrualPayments"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StandardProductWarrantyAccrualPayments" xlink:to="lab_us-gaap_StandardProductWarrantyAccrualPayments" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_CommercialLEDFLTubularLEDLampsExcludingBatteryBackupTLEDTrofferLuminairesAndCertainGlobeLightsMember_d2016acc-08af-4649-b218-c8f903ce4334_terseLabel_en-US" xlink:label="lab_efoi_CommercialLEDFLTubularLEDLampsExcludingBatteryBackupTLEDTrofferLuminairesAndCertainGlobeLightsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commercial LEDFL Tubular LED Lamps (Excluding Battery Backup TLED), Troffer Luminaires, And Certain Globe Lights </link:label>
<link:label id="lab_efoi_CommercialLEDFLTubularLEDLampsExcludingBatteryBackupTLEDTrofferLuminairesAndCertainGlobeLightsMember_label_en-US" xlink:label="lab_efoi_CommercialLEDFLTubularLEDLampsExcludingBatteryBackupTLEDTrofferLuminairesAndCertainGlobeLightsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commercial LEDFL Tubular LED Lamps (Excluding Battery Backup TLED), Troffer Luminaires, And Certain Globe Lights [Member] </link:label>
<link:label id="lab_efoi_CommercialLEDFLTubularLEDLampsExcludingBatteryBackupTLEDTrofferLuminairesAndCertainGlobeLightsMember_documentation_en-US" xlink:label="lab_efoi_CommercialLEDFLTubularLEDLampsExcludingBatteryBackupTLEDTrofferLuminairesAndCertainGlobeLightsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commercial LEDFL Tubular LED Lamps (Excluding Battery Backup TLED), Troffer Luminaires, And Certain Globe Lights [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_CommercialLEDFLTubularLEDLampsExcludingBatteryBackupTLEDTrofferLuminairesAndCertainGlobeLightsMember" xlink:href="efoi-20201231.xsd#efoi_CommercialLEDFLTubularLEDLampsExcludingBatteryBackupTLEDTrofferLuminairesAndCertainGlobeLightsMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_CommercialLEDFLTubularLEDLampsExcludingBatteryBackupTLEDTrofferLuminairesAndCertainGlobeLightsMember" xlink:to="lab_efoi_CommercialLEDFLTubularLEDLampsExcludingBatteryBackupTLEDTrofferLuminairesAndCertainGlobeLightsMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_PrivatePlacementMember_0fee4d0b-b9e4-4142-8c0e-4a75b64c38fc_terseLabel_en-US" xlink:label="lab_us-gaap_PrivatePlacementMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Private Placement </link:label>
<link:label id="lab_us-gaap_PrivatePlacementMember_label_en-US" xlink:label="lab_us-gaap_PrivatePlacementMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Private Placement [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrivatePlacementMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrivatePlacementMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PrivatePlacementMember" xlink:to="lab_us-gaap_PrivatePlacementMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_FacilityClosingMember_2270b951-cde3-4409-9376-2f31bdf36ec0_terseLabel_en-US" xlink:label="lab_us-gaap_FacilityClosingMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restructuring Liability </link:label>
<link:label id="lab_us-gaap_FacilityClosingMember_label_en-US" xlink:label="lab_us-gaap_FacilityClosingMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Facility Closing [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FacilityClosingMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FacilityClosingMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FacilityClosingMember" xlink:to="lab_us-gaap_FacilityClosingMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_DebtInstrumentRepurchaseAmount_09b95cca-b76b-4b2a-9b74-bab55a8cfed3_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentRepurchaseAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Redemption amount </link:label>
<link:label id="lab_us-gaap_DebtInstrumentRepurchaseAmount_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentRepurchaseAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Repurchase Amount </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepurchaseAmount" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRepurchaseAmount"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRepurchaseAmount" xlink:to="lab_us-gaap_DebtInstrumentRepurchaseAmount" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_31961bcb-8823-472c-b35a-213626d4655f_terseLabel_en-US" xlink:label="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Organization, Consolidation and Presentation of Financial Statements [Abstract] </link:label>
<link:label id="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_label_en-US" xlink:label="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Organization, Consolidation and Presentation of Financial Statements [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:to="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EquipmentMember_88703385-dd52-446c-9731-4a47935afd10_terseLabel_en-US" xlink:label="lab_us-gaap_EquipmentMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equipment </link:label>
<link:label id="lab_us-gaap_EquipmentMember_label_en-US" xlink:label="lab_us-gaap_EquipmentMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equipment [Member] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquipmentMember" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquipmentMember"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquipmentMember" xlink:to="lab_us-gaap_EquipmentMember" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_LiabilitiesCurrentAbstract_5282922e-bcab-44b3-ae0b-8e2a49268af0_terseLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrentAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current liabilities: </link:label>
<link:label id="lab_us-gaap_LiabilitiesCurrentAbstract_label_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrentAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities, Current [Abstract] </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:to="lab_us-gaap_LiabilitiesCurrentAbstract" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_a2ab2ecf-9226-4fa1-837a-f14cce939dfa_terseLabel_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> U.S. statutory rate </link:label>
<link:label id="lab_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_label_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_Plan2014Member_d7dddb59-3c90-406c-b671-68c86297d5ea_terseLabel_en-US" xlink:label="lab_efoi_Plan2014Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2014 Plan </link:label>
<link:label id="lab_efoi_Plan2014Member_label_en-US" xlink:label="lab_efoi_Plan2014Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Plan 2014 [Member] </link:label>
<link:label id="lab_efoi_Plan2014Member_documentation_en-US" xlink:label="lab_efoi_Plan2014Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock incentive plan approved in 2014. </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_Plan2014Member" xlink:href="efoi-20201231.xsd#efoi_Plan2014Member"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_efoi_Plan2014Member" xlink:to="lab_efoi_Plan2014Member" xlink:type="arc" order="1"/>
<link:label id="lab_dei_EntityShellCompany_17e6ea1e-672b-43af-bc0e-49ee5185d56a_terseLabel_en-US" xlink:label="lab_dei_EntityShellCompany" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Shell Company </link:label>
<link:label id="lab_dei_EntityShellCompany_label_en-US" xlink:label="lab_dei_EntityShellCompany" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Shell Company </link:label>
<link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityShellCompany"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityShellCompany" xlink:to="lab_dei_EntityShellCompany" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease_f3a9dad0-0f61-47fe-865b-c0d7a46d2fc0_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Issuance of common stock and warrants (in shares) </link:label>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Issued During Period, Shares, Period Increase (Decrease) </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_716b4d6f-cdc4-4773-a9ce-ab5b2cb663e1_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock withheld in lieu of income tax withholding from share-based compensation (in shares) </link:label>
<link:label id="lab_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_label_en-US" xlink:label="lab_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xlink:to="lab_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xlink:type="arc" order="1"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_5a3d25d9-f316-4523-a21d-941aeba6402b_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vested and expected to vest (in dollars per share) </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price </link:label>
<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice"/>
<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:type="arc" order="1"/>
<link:label id="lab_efoi_FiveElementsEfficientiesBVILtdMember_c711c6cd-3e52-40dd-a7e1-40841796c975_terseLabel_en-US" xlink:label="lab_efoi_FiveElementsEfficientiesBVILtdMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 5 Elements Efficiencies (BVI) Ltd. </link:label>
<link:label id="lab_efoi_FiveElementsEfficientiesBVILtdMember_label_en-US" xlink:label="lab_efoi_FiveElementsEfficientiesBVILtdMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Five Elements Efficienties BVI Ltd [Member] </link:label>
<link:label id="lab_efoi_FiveElementsEfficientiesBVILtdMember_documentation_en-US" xlink:label="lab_efoi_FiveElementsEfficientiesBVILtdMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 5 Elements Efficienties (BVI) Ltd. </link:label>
<link:loc xlink:type="locator" xlink:label="loc_efoi_FiveElementsEfficientiesBVILtdMember" xlink:href="efoi-20201231.xsd#efoi_FiveElementsEfficientiesBVILtdMember"/>
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9 Subsequent Filings that Reference this Filing

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 3/22/24  Energy Focus, Inc./DE             10-K       12/31/23  109:8.8M                                   Workiva Inc Wde… FA01/FA
 3/23/23  Energy Focus, Inc./DE             10-K       12/31/22  106:9.1M
 6/28/22  Energy Focus, Inc./DE             424B3                  1:132K
 6/17/22  Energy Focus, Inc./DE             S-3                    5:286K
 3/17/22  Energy Focus, Inc./DE             10-K       12/31/21  109:10M
 1/10/22  Energy Focus, Inc./DE             424B3©                 1:141K
12/28/21  Energy Focus, Inc./DE             S-3                    4:218K
12/28/21  Energy Focus, Inc./DE             S-3                    4:281K
 6/16/21  Energy Focus, Inc./DE             424B5                  1:233K

20 Previous Filings that this Filing References

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 9/22/20  Energy Focus, Inc./DE             8-K:5,9     9/17/20    6:398K
 8/13/20  Energy Focus, Inc./DE             10-Q        6/30/20   73:8.6M
 6/11/20  Energy Focus, Inc./DE             8-K:3,5,7,9 6/11/20    3:92K
 5/18/20  Energy Focus, Inc./DE             8-K:5,9     5/12/20   13:448K
 5/13/20  Energy Focus, Inc./DE             10-Q        3/31/20   67:6.7M
 3/24/20  Energy Focus, Inc./DE             10-K       12/31/19   92:8.5M
 1/13/20  Energy Focus, Inc./DE             8-K:1,3,7,9 1/09/20    7:487K                                   Donnelley … Solutions/FA
 7/22/19  Energy Focus, Inc./DE             10-Q        3/31/19   59:4.7M
 7/19/19  Energy Focus, Inc./DE             8-K:5       7/19/19    2:72K
 5/30/19  Energy Focus, Inc./DE             8-K:1,3,4,5 5/21/19    3:116K
 4/01/19  Energy Focus, Inc./DE             8-K:1,2,3,5 3/29/19    8:1M
 2/26/19  Energy Focus, Inc./DE             8-K:1,5,7,9 2/21/19    3:224K
 2/22/18  Energy Focus, Inc./DE             10-K       12/31/17   87:8.6M
 5/11/16  Energy Focus, Inc./DE             10-Q        3/31/16   51:18M
 7/27/15  Energy Focus, Inc./DE             8-K:5,9     7/22/15    2:320K                                   Workiva Inc Wde… FA01/FA
 7/16/14  Energy Focus, Inc./DE             8-K:5,9     7/15/14    7:594K                                   RDG Filings/FA
11/13/13  Energy Focus, Inc./DE             10-Q        9/30/13   76:7.6M                                   RDG Filings/FA
 8/16/13  Energy Focus, Inc./DE             DEF 14A     9/26/13    1:1.1M                                   RDG Filings/FA
 6/08/12  Energy Focus, Inc./DE             PRER14A¶               2:663K                                   Donnelley … Solutions/FA
 5/10/07  Energy Focus, Inc./DE             10-Q        3/31/07    6:427K                                   Toppan Merrill/FA
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