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Emission Factors API

Authoritative greenhouse-gas emission factors with the provenance a reporting team actually needs to cite: 13,000+ factors covering Scope 1, 2 and 3, drawn from four editions (2023-2026) of the UK DEFRA/DESNZ conversion factors and the US EPA GHG Emission Factors Hub. Fuels, UK and US grid electricity (including every eGRID subregion), passenger and delivery vehicles by size and fuel, freight by mode and tonne.km, flights by haul and cabin class, rail, sea, hotel stays, homeworking, water supply and treatment, material use, waste by disposal route, and refrigerants with their AR5 global warming potentials. Every factor carries kg CO2e per unit plus the CO2 / CH4 / N2O split, the gases it actually covers, whether the CO2e was published or derived, the GWP basis used, and the exact source file and licence it came from. Because the API keys on a stable semantic slug rather than the publisher's own row id — which is not stable between editions — you can pull the same activity across years to restate a prior reporting period. A calculate endpoint turns activity data into kg CO2e in one call, single or batched, totalled by scope, keeping biogenic CO2 out of the scope totals and warning when a factor covers only some gases. A weekly job re-checks each publisher and records whether the file behind every edition is still the one we parsed, exposed at /v1/factors/updates so you can verify the dataset is current rather than take it on trust. Self-hosted dataset built from free, redistributable government sources — no third-party calls at request time.