Activity data
Activity data are quantitative measures of activities that cause or remove greenhouse gas emissions, such as fuel consumed, electricity purchased, distance travelled, waste treated, or tonnes of product made. An inventory calculates emissions by combining appropriately bounded activity data with a compatible emission factor and any required conversion or oxidation parameters.
In simple terms
Activity data answer the question, ‘how much activity occurred?’ They form one side of a greenhouse gas calculation; the emission factor translates that activity into an estimated quantity of emissions or removals. Useful data must match the inventory boundary, reporting period, technology, geography, and units of the chosen factor. Sources may include utility bills, fuel records, meters, purchase ledgers, logistics systems, production data, or defensible estimates. Teams should document units, conversions, gaps, assumptions, and data quality before aggregation.
Why it matters
Reliable activity data underpin credible greenhouse gas inventories, baselines, targets, and Climate mitigation decisions. Poorly matched units, boundaries, or periods can create material errors even when the emission factor is authoritative. Tracking the underlying activity also reveals operational drivers and helps teams distinguish real performance changes from updates to calculation factors or methods.
Example
A manufacturer records 120,000 kilowatt-hours of purchased electricity for one facility during the reporting year. It confirms that the meter and organizational boundary align, then multiplies the figure by the applicable electricity emission factor. The calculation retains the bill, units, factor version, and conversion steps as evidence.
How it differs
Emission factor
Activity data quantify the underlying activity, while an emission factor expresses the emissions or removals associated with each unit of that activity.