Chapter 08 · Finance, data & evidenceData, Technology & Verification Systems
Activity data
Definition
A quantitative measure of a level of activity that results in greenhouse gas emissions, expressed in physical units such as litres of fuel, kilowatt-hours of electricity, kilograms of material or tonne-kilometres of freight. Activity data are multiplied by emission factors to estimate emissions, forming the basis of most greenhouse gas inventories under the GHG Protocol.
References
Emission factors relate emissions to activity performed; activity data (distance travelled, fuel combusted) as the basis for calculation; scope definitions.
Activity-based vs spend-based methods; activity data as default for Scopes 1–2; hybrid approaches for Scope 3.
GHG Protocol Scope 3 data hierarchy (supplier-specific, hybrid, average-data, spend-based); regulatory direction of travel.
Overview
What it means
The GHG Protocol's Scope 3 Standard ranks data types by accuracy: supplier-specific (primary) data, hybrid, average-data and spend-based estimates.
"Activity-based" calculation — physical activity data multiplied by matching emission factors — is the default for Scope 1 and 2 and the preferred approach for material Scope 3 categories; spend-based estimation is a lower-accuracy fallback used where activity data are unavailable.
How it is used
Companies collect activity data from utility bills, fuel records, procurement systems and suppliers, then apply factors from sources such as the US EPA, UK DESNZ or the IPCC Emission Factor Database. Assurance providers test activity data quality, and regulations such as the EU carbon border adjustment mechanism increasingly require activity-based rather than spend-based figures.
Why it matters
Emissions figures are only as credible as the activity data beneath them. The shift from spend-based estimates to activity-based data is the main lever for improving inventory accuracy, auditability and the ability to track real-world reductions.