2026 UK Government Conversion Factors Download Major changes, and what they mean for corporate footprints.

This year the story is unusually concentrated. Almost every material change traces back to one source: electricity. Direct fuel combustion barely moved. That makes the 2026 update easy to summarise but easy to misread, because a large part of the headline reduction is a change in method and timing rather than a change in the real world.

Here is what moved, why, and what it means for the numbers you report.

The headline: UK electricity falls around 26%

The UK grid average electricity factor falls by about 26% compared with the 2025 set (with methane down 26% and nitrous oxide down 30%). On its own that looks like a strong decarbonisation signal. The detail is more nuanced.

DESNZ has changed the methodology so that the data used now lags the publication year by one year instead of two. The consequence is important: this single update absorbs two years of grid change rather than the usual one. DESNZ breaks the fall down as follows:

• Around 16 percentage points come from changes in the grid generation mix between 2023 and 2024.
• Around 3 percentage points come from the additional year of data (2024 to 2025).
• The remaining 6 to 7 percentage points come from methodology improvements and corrections. These include correcting a double-counting issue that affected autogenerators, improving how the calculation handles electricity imports and exports, and updated treatment of grid losses.

In plain terms: a business with identical electricity consumption this year and last will see its Scope 2 location-based emissions drop sharply, and most of that drop is timing and method, not something the business did.

Everything downstream of electricity moves with it

Because so many factors are built on top of the grid figure, the 26% fall ripples through the dataset.

• Transmission and distribution (T&D) losses fall by about 30% (with methane down 13% and nitrous oxide down 18%). This sits in Scope 3.
• Well-to-tank (WTT) electricity falls by about 20% for generation and 10% for T&D. These factors had not been updated since the 2023 publication, so they catch up on several years of grid change in one step. Note that the underlying WTT values for fuels were not updated this cycle.
• Electric vehicles (battery electric and plug-in hybrid, cars and vans) fall broadly between 12% and 37%, with the larger reductions driven by the electricity change combined with genuine efficiency gains in newer models. MPVs fall the most, by 36% to 37%, because the latest models are markedly more efficient and now make up a larger share of registrations.
• Homeworking (office equipment) falls by about 31% as a result of the electricity grid factor change, and because it had not been updated since 2022 – so it captures several years of grid decarbonisation at once.

Real-world notable changes:

A handful of other changes this year are driven by new activity data, and some are large enough to notice in a footprint:

• Coaches up 42% to 43%. New data from a large coach operator replaced figures that implied unrealistically high occupancy. The revised numbers sit in line with typical coach efficiency and occupancy.
• International rail up 154% to 156%. Service patterns and use of rolling stock have changed substantially since the pre-pandemic figures these factors replaced. A dramatic increase, though most likely relevant only to organisations with material international rail travel.
• National rail down 13%, light rail and tram down 26%, London Underground down 44% to 45%, reflecting grid changes and large revisions to passenger kilometres versus older pre-COVID estimates.
• Heavy goods vehicles swing on how heavily they are loaded. Rigid vehicles between 7.5 and 17 tonnes rise about 18% per tonne.km because average loading fell, while articulated vehicles fall about 6.2% because loading rose. These follow trends in DfT road freight statistics.
• Plug-in hybrid vans up 11% to 16%, as new Class III models registered in 2024 show higher real-world energy use, and sports plug-in hybrid cars up around 9.5% for similar reasons.
• Refrigerant R-511A corrected to zero (down 100%, from 6.9 kgCO2e per kg), a blend-composition correction. Niche, but worth a check for anyone using it.