DEFRA Emission Factors
DEFRA emission factors are conversion factors published annually by the UK government that allow organisations to calculate greenhouse gas emissions from common activities such as electricity consumption, fuel use, and travel.
What is DEFRA Emission Factors?
DEFRA emission factors — now officially published by the Department for Energy Security and Net Zero (DESNZ), though still widely referred to as "DEFRA factors" — are the standard conversion factors used in the UK to translate business activity data into greenhouse gas emissions. They are published annually, typically in June, and cover the UK's financial year.
The official title is the "UK Government GHG Conversion Factors for Company Reporting." The dataset is comprehensive and covers dozens of emission source categories, including: electricity (grid average, by country), natural gas, LPG, gas oil, fuel oil, burning oil, diesel, petrol, CNG, LNG, aviation fuels, biofuels and blended fuels, refrigerant gases (by type and GWP), water supply and treatment, waste disposal (by type and method), business travel (by mode and class), freight transport (by vehicle type and load), hotel stays, and more.
Each factor provides a conversion from a unit of activity (e.g., 1 kWh of electricity, 1 litre of diesel, 1 tonne-km of freight) to kilograms of CO₂e. The CO₂e figure combines the global warming potential of the three main greenhouse gases: CO₂, CH₄, and N₂O. For some sources (like refrigerants), the factors cover specific gases such as HFCs and PFCs with their individual GWP values.
The factors are divided into several scopes: Scope 1 factors for direct combustion fuels, Scope 2 factors for purchased electricity, and Scope 3 factors for indirect categories like business travel, waste, and water. The dataset also includes well-to-tank (WTT) factors, which account for the upstream emissions from extracting, refining, and transporting fuels before they are combusted.
DEFRA factors are the default choice for UK carbon reporting under SECR, the GHG Protocol, CDP, and the Carbon Reduction Plan. For international operations, organisations typically use country-specific grid factors from the IEA or local energy agencies, supplemented by DEFRA factors for fuel combustion and other activity types.
It is important to use the correct year's factors for each reporting period. Factors change annually as the electricity grid decarbonises, fuel supply chains evolve, and scientific understanding of GWP values is updated. Using outdated factors can introduce material errors and undermine the credibility of reported figures.
Practical Examples
An organisation consuming 500,000 kWh of UK grid electricity in 2024 multiplies by the DEFRA 2024 electricity factor (~0.207 kgCO₂e/kWh) to calculate approximately 103.5 tCO₂e of Scope 2 emissions.
A fleet manager converts 50,000 litres of diesel consumed by company vehicles into tCO₂e using the DEFRA factor for diesel (approximately 2.51 kgCO₂e per litre), arriving at roughly 125.5 tCO₂e.
A sustainability manager uses DEFRA waste disposal factors to calculate emissions from 200 tonnes of mixed waste sent to landfill versus recycling, demonstrating the carbon benefit of diversion from landfill.
How Climatise Helps
Climatise maintains a complete, up-to-date library of over 50,000 emission factors including every DEFRA/DESNZ factor, updated annually when new datasets are published. The platform automatically selects the correct factor based on the activity type, unit, and reporting year — eliminating manual lookups and formula errors.
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