Concept
Emission factor
Also: EF · characterisation factor · GHG emission factor
A coefficient that converts a quantity of activity, such as a kilowatt-hour of electricity or a kilogram of steel, into an estimated quantity of greenhouse gas emissions or other environmental impact.
Emission factors are the multipliers at the heart of every carbon footprint and life cycle inventory. Activity data, such as tonnes of material purchased or litres of fuel burned, are multiplied by an emission factor to estimate emissions.
Sources
Emission factors come from life cycle inventory databases such as ecoinvent, from national inventories and government publications, from industry associations, and increasingly from suppliers themselves in the form of supplier-specific product carbon footprints. Each source carries its own boundary, geography, technology mix and reference year.
Why they need checking
An emission factor is only valid for the activity, region and period it describes. Applying a European grid factor to a factory in Southeast Asia, or a 2015 factor to 2026 production, changes the result materially. In large reports, factor selection errors are common, quiet and hard to find by sampling.
Characterisation factors
In a full LCA, characterisation factors perform a similar role at the impact assessment stage, converting inventory flows into impact category indicators such as kg CO2e or kg SO2e.
Where Verdatir fits
Verdatir cross-checks the emission factors in a submission against their stated source, region and vintage, and flags factors that do not match the activity they are applied to.
Sources and further reading
In practice
Verdatir turns the rules behind this term into automated checks with a reviewer in the loop.
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