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Definition

Combustion vs life-cycle emission factors

A combustion emission factor covers greenhouse gases released when fuel is burned, while a life-cycle emission factor also covers stages such as extraction, processing, and transport.

What are combustion vs life-cycle emission factors?

A combustion emission factor counts emissions released when fuel burns. A life-cycle emission factor includes combustion plus extracting, processing, and transporting the fuel. Under GHG Protocol, combustion factors calculate Scope 1 fuel emissions; life-cycle or upstream factors support Scope 3 calculations.

Why do combustion vs life-cycle emission factors matter to you?

A customer or reviewer may ask for the factor source, year, geography, unit, and included stages. Mixing combustion-only and life-cycle factors without disclosure makes fuel lines with the same litres incomparable.

How do combustion vs life-cycle emission factors work?

Multiply fuel consumed by the factor with the matching unit. GHG Protocol Scope 3 Calculation Guidance formula [3.1] defines the upstream factor as the life-cycle factor minus the combustion factor. Use combustion and life-cycle factors for the same reporting year, fuel specification, unit, and geography. Report combustion in Scope 1 and upstream fuel emissions in Scope 3 category 3.

What mistakes should you avoid?

  • Calling a combustion result life-cycle emissions when extraction, processing, and transport are excluded.
  • Adding a full life-cycle result to Scope 1 and reporting the combustion portion again.
  • Subtracting factors from different years, fuels, units, or geographies.
  • Treating a missing upstream factor as zero instead of marking the life-cycle total incomplete.

Does a combustion factor include upstream fuel emissions?

No. Section 2.1 of the UK DESNZ 2026 methodology assigns fuel factors to combustion at an owned or controlled site and separate well-to-tank factors to extraction, refining, and transport before combustion.

What should you send when someone asks which factor you used?

Send the activity record, exact factor value and unit, factor ID, publisher, dataset version, year, geography, included stages, calculation, and Scope classification. Label every proxy and keep combustion and upstream results on separate lines.

Example

Saudi cold-chain warehouse example: Suppose a hypothetical operator uses 12,000 litres of diesel in owned backup generators during 2026. To calculate the combustion part only, it uses Keslio factor fuel_diesel_litre_average_biofuel_blend_desnz_2026: 2.58354 kg CO2e/litre from UK DESNZ and DEFRA's UK Government GHG Conversion Factors for Company Reporting 2026. The operator records this as a UK-government proxy because the factor is not Saudi-specific.

12,000 litres x 2.58354 kg CO2e/litre = 31,002.48 kg CO2e. Divide by 1,000 to report 31.00248 tCO2e.

This is a combustion-only Scope 1 estimate. Once the operator has a well-to-tank factor with matching units and coverage, upstream emissions = 12,000 litres x well-to-tank factor, and life-cycle emissions = 31,002.48 kg CO2e + upstream emissions. Until then, it should report only the combustion result and mark the life-cycle total incomplete.

Where it comes up

GHG Protocol distinction between combustion and life-cycle emission factors for Scope 1, Scope 2, and Scope 3GHG Protocol Corporate Standard FAQ, 'What is the difference between a combustion and life cycle emission factor?', checked 2026-08-20Official sourceGHG Protocol upstream purchased-fuel factor and separate Scope 3 category 3 calculationGHG Protocol Scope 3 Calculation Guidance, Category 3, Calculation formula [3.1]Official source

Related terms

Emission factor

An emission factor converts a measured activity, such as kilowatt-hours of electricity or litres of fuel, into greenhouse gas emissions by stating the emissions released per unit of that activity.

Scope 1 Emissions

Scope 1 emissions are greenhouse gases released directly from sources your company owns or controls, including fuel-burning equipment and vehicles, industrial processes, and refrigerant or other gas leaks.

Scope 3 Emissions

Scope 3 emissions are the indirect greenhouse gas emissions from goods, services, transport, product use, investments, and other upstream and downstream activities outside your company's Scope 1 and Scope 2 boundary.

Life cycle assessment (LCA)

A life cycle assessment (LCA) estimates a product's or service's potential environmental impacts for a defined function and life-cycle boundary, using recorded inputs, stated impact methods, and a documented interpretation of the results.

Sources

  • GHG Protocol

    Combustion-only and life-cycle factor definitions and their use across Scope 1, Scope 2, and Scope 3

    2026-08-20

  • GHG Protocol

    Energy-factor boundaries, Scope 3 category 3 treatment, formula [3.1], and factor matching

    2026-08-20

  • UK Department for Energy Security and Net Zero

    Current 2026 conversion-factor dataset, direct fuel factors, separate well-to-tank factors, and worked-example source

    2026-08-20

Last verified 2026-08-20

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Combustion vs life-cycle emission factors Definition | Keslio