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The Department for Energy Security and Net Zero (DESNZ) has published the 2026 edition of the Government Greenhouse Gas Conversion Factors for Company Reporting. Produced annually, these factors are the standard reference used by UK businesses to calculate their Scope 1, 2, and 3 greenhouse gas emissions under frameworks including SECR, the GHG Protocol, and NHS Net Zero reporting requirements.
This year's update contains several changes substantial enough to materially affect disclosed emissions figures ,particularly for organisations with significant electricity consumption, fleet operations, or commuter and business travel.
The most significant change is a 26% reduction in the electricity emission factor. This is partly genuine grid progress, coal and gas have continued to decline in the generation mix, but also reflects a methodological shift. Previously, the data used to calculate the factor lagged publication by two years. From 2026, that lag has been reduced to one year. This means the 2026 factor captures two years' worth of grid decarbonisation in a single update rather than one, amplifying the apparent magnitude of the drop. Organisations should note this when explaining year-on-year emissions reductions to stakeholders: some of the improvement will be attributable to the methodology change rather than operational action.
Transmission and distribution losses also fell by 30% for CO2e, for the same combination of reasons.
EV and PHEV emission factors dropped substantially,. 23–26% for most car categories, driven primarily by the electricity factor change, with vehicle efficiency improvements adding a secondary effect. The London Underground factor dropped by 44–45%, and light rail and tram by 26%, both reflecting grid changes alongside updated ridership data that had been held at pre-pandemic baselines since 2021.
Coach travel is a notable exception: the factor increased by 42–43% after new data from a major operator corrected an implausibly high assumed occupancy rate used in previous editions. National rail fell 13% on updated passenger kilometres.
One anomaly worth flagging: international rail increased by 154–156%. This is attributed to changes in service patterns and rolling stock utilisation post-COVID rather than any meaningful deterioration in rail efficiency, but it will produce jarring figures for any organisation reporting Eurostar or cross-border rail journeys.
HGV factors show opposing trends depending on vehicle class: rigid HGVs (7.5–17 tonnes) rose 18% on tonne.km because average load factors declined, while articulated HGVs (>3.5–33t) fell 6.2% because load factors improved. Both movements reflect real shifts in domestic freight patterns captured in DfT Road Freight Statistics.
For most UK businesses, 2026 figures will show lower Scope 2 emissions and lower emissions from EV/PHEV fleets even without any operational changes. This creates a risk of overstating progress if year-on-year comparisons are not normalised for factor changes, a point worth making explicitly in any narrative reporting.
Organisations using spend-based or distance-based methods for business travel should review their coach and international rail categories specifically, as the factor shifts are large enough to cause material changes to totals.
The refrigerant correction for R-511A (a -100% change for Kyoto-scope emissions) is relevant for any site using this blend; the previous published value was simply incorrect.
The homeworking factor fell 31%, reflecting both the grid change and the fact it had not been updated since 2022, making the 2026 value a three-year catch-up in a single step.
Every year the government updates its conversion factors. Every year that means rechecking your numbers, updating your methodology, and explaining the changes to stakeholders. Climate Essentials handles all of that for you, keeping your emissions data accurate, up to date, and ready for scrutiny.
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