Corporate carbon footprint: what it is and how to calculate it
The measure of an organisation's greenhouse gas emissions: methodology, starting documents and mistakes to avoid.
The corporate carbon footprint is the measure of all greenhouse gas emissions generated by an organisation over a period, expressed in tonnes of CO₂ equivalent (tCO₂e). It is the starting figure for any sustainability path: without a reliable measure there are neither credible reports nor sensible reduction plans.
What is measured exactly
The emissions of the seven greenhouse gases of the Kyoto Protocol are measured, converted into CO₂ equivalent so they can be summed. The boundary follows the three categories of the GHG Protocol: Scope 1 for direct emissions (fuels, fleet, processes), Scope 2 for purchased energy, Scope 3 for the value chain.
The methodology: from activity data to emission
The calculation has a simple structure: activity data × emission factor = emission. The activity data are your real consumption: kWh from the bill, litres of diesel from the invoice, kilograms of waste from the FIR. The emission factor is the coefficient that converts that consumption into tCO₂e, published by official sources and updated every year.
The quality of the result depends on two things: activity data taken from documents (not estimated) and factors that are up to date and traced by source and year.
The documents to start from
For most SMEs these are enough: electricity and gas bills, fuel and fuel-card invoices, FIR and waste registers, invoices for transport outsourced to third parties, travel expense reports, purchase invoices for the relevant Scope 3 categories. These are documents that administration already files every month: the work is the extraction, not the collection.
The mistakes of the first calculation
- Undeclared boundary: which sites and companies are included must be explicit.
- Estimates instead of documents: if the bill exists, the bill is used.
- Outdated factors: the electricity grid factor changes every year.
- Scope 3 ignored: for many companies it is the largest part. Better a few relevant categories done well than none.
Activity data (from the document) × emission factor (up to date and traced) = emission in tCO₂e. Everything else is work organisation.
