Measurement & boundary

Emission factors

The conversion values that turn activity into emissions — litres of fuel into kilograms of CO2e, kilowatt-hours into carbon, kilograms of steel into embedded emissions. Every reported footprint is activity data multiplied by a factor.

Corewell covered

What it is

Emission factors are the least visible and most consequential decision in carbon accounting. Two companies with identical operations can publish materially different footprints purely because they selected different factor sets. Factors come from several places: national inventories, industry databases, supplier-specific calculations. They vary by geography, by year, and by methodology. A grid electricity factor for India differs from Germany's, and both change annually as the generation mix shifts. The governance question matters more than the arithmetic. Can you say which factor source you used for each category, why it was appropriate, and when you last refreshed it? Can you show that the same choice was applied consistently across reporting periods, so year-on-year comparisons mean something? Companies that can't answer those questions usually discover it during assurance, at the point where it is most expensive to fix.

Why it matters

Change the factor and the number changes, without anything happening in the real world. Which factor you chose, why, and when it was last updated are among the first things an auditor asks about — and among the last things most companies can answer.

How it connects

measures

regulates

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