Each year DESNZ publishes the UK Government greenhouse gas conversion factors for company reporting. They are the standard factors for SECR, PPN 006 Carbon Reduction Plans and most UK corporate footprints. The 2026 set was published in June 2026. We load the full flat file (version 1.2, revised July 2026) as the DEFRA 2026.1 library.
The changes that matter most
All figures are kg CO₂e per unit, taken from the DESNZ flat files for 2025 (v1) and 2026 (v1.2).
| Factor | Unit | 2025 | 2026 | Change |
|---|---|---|---|---|
| UK electricity generated (location-based) | kWh | 0.17700 | 0.13096 | −26.0% |
| UK electricity transmission and distribution losses | kWh | 0.01853 | 0.01299 | −29.9% |
| Natural gas (gross CV) | kWh | 0.18296 | 0.18231 | −0.4% |
| Diesel (average biofuel blend) | litre | 2.57082 | 2.58354 | +0.5% |
| Petrol (average biofuel blend) | litre | 2.06916 | 2.07500 | +0.3% |
| HVO | litre | 0.03558 | 0.03558 | 0% |
| Van up to 3.5 t, diesel | km | 0.25561 | 0.25716 | +0.6% |
| Commercial and industrial waste to landfill | tonne | 520.53 | 520.58 | +0.0% |
| Inert construction waste to landfill | tonne | 1.26338 | 1.27043 | +0.6% |
Electricity is the big one. A site using 100,000 kWh of grid electricity reports 17.7 tCO₂e with the 2025 factor and 13.1 tCO₂e with the 2026 factor, with no change in use. DESNZ changed the electricity method in 2026 to use more recent generation-mix data, so the factor lags the grid less than before.
Diesel barely moves. For most contractors, fuel in plant and vehicles is the largest Scope 1 source. Changes in the factors will not reduce it; burning less will. See idling plant.
HVO stays very low in the scopes, 0.03558 kg CO₂e per litre, with its biogenic CO₂ reported separately outside the scopes.
Choosing the right year
- Match the reporting year. A calendar 2026 report uses the 2026 set.
- For a period that straddles two years, pick a rule, such as the year in which the period ends, and use it every year. MetricOra picks the newest DEFRA set whose year is not after the period's end year, and warns when a run uses a different library.
- Name the set in the methodology. "DEFRA 2026" is ambiguous; "UK Government GHG conversion factors 2026, flat file v1.2" is not.
- Explain the effect. When a total falls because of new factors, say so. Otherwise a reader will count it as a real reduction. Holding activity constant and recalculating with the new factors gives the split.
Location-based and market-based
The 0.13096 figure is the location-based grid average. Under the GHG Protocol Scope 2 Guidance, organisations also report a market-based figure using supplier-specific factors, certificates such as REGOs, and a residual mix. We explain the difference in location-based and market-based Scope 2.
In MetricOra
DEFRA 2025.2 and 2026.1 are both loaded in full from the flat files, alongside US EPA, EPA USEEIO 1.3, ADEME Base Carbone and the Defra UK spend multipliers. Each calculation run is pinned to one library and stores the factor, formula and selection reason for every record. So "which factors did you use?" always has an exact answer. See the methodology.
Frequently asked questions
What is the 2026 UK electricity factor? 0.13096 kg CO₂e per kWh generated (location-based), plus 0.01299 for transmission and distribution losses.
Which year's factors should I use? The set matching your reporting year, applied consistently and named in your methodology.
Should I restate the previous year? Not for a factor update alone; show the effect of the new factors instead.