Data · DESNZ GHG conversion factors 2025
GHG conversion factors 2025: when the 2025 set still applies
The GHG conversion factors 2025, still widely called the DEFRA emission factors 2025, were published by DESNZ on 10 June 2025.
They remain the right set for activity that fell mostly in 2025, including many financial years ending in early 2026, even though the 2026 factors are now out.
The UK electricity factor in the 2025 set is 0.17700 kgCO2e per kWh.
The first decision
2025 or 2026: match the activity year
DESNZ’s rule is the same every year: the 2026 methodology paper, ¶1.10, says the 2026 factors are “for use with activity data that falls entirely or mostly within 2026”.
The 2025 methodology paper carries the same construction for 2025, at ¶1.8.
So the year that matters is the year the energy was used or the journey made, not the year the report is written or filed.
A financial year ending on 31 March 2026 has nine months in 2025, so it falls mostly within 2025 and uses the 2025 set.
A year that splits evenly is a judgement: take one set for the whole year, or apply each set to its own months, and say which you did.
The stakes are unusually high this time, because the UK electricity factor fell about 26% between the two sets.
| Reporting period | Mostly in | Set |
|---|---|---|
| 1 Jan – 31 Dec 2025 | 2025 | 2025 set |
| 1 Apr 2025 – 31 Mar 2026 | 2025 (9 of 12 months) | 2025 set |
| 1 Jul 2025 – 30 Jun 2026 | Split evenly | Judgement; say which |
| 1 Oct 2025 – 30 Sep 2026 | 2026 (9 of 12 months) | 2026 set |
| 1 Jan – 31 Dec 2026 | 2026 | 2026 set |
The headline factors
UK electricity in the 2025 set
Table 9 of the 2025 methodology paper gives the UK electricity factors for data year 2023, which is the year the 2025 set was built on.
| kgCO2e per kWh | 2025 set | 2026 set |
|---|---|---|
| Generated (Scope 2, location-based) | 0.17700 | 0.13096 |
| T&D losses (Scope 3) | 0.01853 | 0.01299 |
| Consumed, including losses | 0.19553 | 0.14396 |
| Data year | 2023 | 2025 |
The generation factor is the Scope 2 figure; transmission and distribution losses are reported separately in Scope 3, category 3.
Fuel, vehicle, travel and waste factors are in the 2025 workbooks; this page does not reproduce them, because a factor should be taken from the file rather than from a summary.
The widely repeated 0.17889 is not the 2025 factor; the set’s figure is 0.17700.
Your electricity, on both factor sets
Same kilowatt-hours, different factor set: Scope 2 moves by -11.51 tCO2e without any change in what you used.
Computed from DESNZ methodology papers 2025 and 2026, Table 9. Illustrative arithmetic, not a reported figure.
2024 → 2025
What changed in the 2025 update
DESNZ’s 2025 major changes report lists every movement over 5% for Scope 1 and 2 sources and over 10% for Scope 3, against the 2024 set.
| Factor | Change vs 2024 | DESNZ reason (paraphrased) |
|---|---|---|
| UK electricity | −15% | "Less natural gas use in power stations and increase in net imports of electricity" |
| Managed assets, electricity | −15% | As for UK electricity |
| Business travel, air (all factors) | −16% to −42% | Last updated on COVID-affected 2021 data; load factors have recovered |
| Freight flights | −18% to −23% | As above, plus an updated aviation model |
| UK electricity for EVs, cars | −13% to −22% | The electricity factor, plus more efficient new vehicles |
| Sports PHEV cars | +14% to +16% | A new model with higher direct emissions |
| HGVs, rigid and articulated | +11% to +14% | Less loaded per vehicle (DfT data) |
| Class I petrol vans, freight | +22% | Lower average payload |
| Water supply | +25% | Latest water-company data; considerable variation year to year |
| Some waste factors (e.g. incineration with energy recovery) | −27% | MRF operation now 1.64 kg per tonne, from 3.44 |
| Grass/straw bioenergy | −12% | Better power-station methane data |
| Several biofuel WTT factors | −27% to +125% | RTFO feedstock mix changes |
Transmission and distribution, well-to-tank electricity, fuels, heat and steam, homeworking and hotel stays show no major changes in 2025.
The 2025 electricity fall was a normal one-year move on the old two-year lag, which is why it is so much smaller than the 2026 fall.
Crossing the break
Comparing 2025 with 2026: the missing year
The 2026 set changed how the electricity factor is built: the 2026 methodology paper, ¶3.8, says the 2025 publication used 2023 data and the 2026 publication uses 2025 data.
So no published set is built on 2024 data, and a trend drawn straight from the 2025 set to the 2026 set contains two years of grid change plus a methodology revision.
DESNZ’s 2026 major changes report says most of the 26% fall is grid decarbonisation between 2023 and 2024, and 6 to 7 points are methodology.
If your 2025 figures stand beside 2026 figures in a SECR report or a trend chart, footnote the change of set and the data-year break.
Whether to restate 2025 on the new method is your decision under your reporting standard; DESNZ’s ¶3.7 says so rather than directing either way.
Appendix 2 of each methodology paper restates the electricity series on that year’s method.
The 2025 paper’s Appendix 2 shows 0.17721 for data year 2023, but the factor in the 2025 set is the Table 9 figure, 0.17700.
The file
The last year with a condensed set
The 2025 release offered three sets: a condensed set, “recommended for most, and new, users”, a full set “for advanced users only”, and a flat file for automated processes.
The 2026 release dropped the condensed set, as the 2026 methodology paper records at ¶2.3.
If your 2025 calculation used the 2025 condensed set, it remains the right file for 2025 activity; do not switch 2025 figures to the 2026 full set.
The 2025 release told regular users to read the “what’s new” sheet, and new users the introductory worksheet of the condensed set.
Using the 2025 set in a report
What to write in the methodology note
SECR requires a statement of the methodologies used (Sch 7 ¶16 and ¶20F), and prior-year comparatives (¶18, ¶18A and ¶20H), so a 2026 report will often show 2025 beside it.
Name the factor set used for each year, for example “UK Government GHG Conversion Factors for Company Reporting 2025 (DESNZ)”.
UK SRS S2 asks for the same transparency: ¶B29 requires information on which emission factors were used, and ¶29(a)(iii)(3) any changes to the approach and why.
How the SECR figures are laid out is in our SECR reporting template, and the calculation in SECR carbon reporting.
For which scope each line belongs to, see Scope 1, 2 and 3 emissions.
Where to get them
Downloading the 2025 files
All five 2025 documents are on the 2025 publication page, and every earlier year is on the GOV.UK collection.
Direct files: the 2025 condensed set, the 2025 full set and the 2025 flat file.
The 2025 methodology paper and major changes report explain how the figures were built.
Frequently asked
Questions people ask
What is the 2025 UK electricity emission factor?
The UK electricity generation factor in the 2025 set is 0.17700 kgCO2e per kWh, for location-based Scope 2 on UK grid electricity used in 2025. Transmission and distribution losses add 0.01853 kgCO2e per kWh in Scope 3, and electricity consumed including losses is 0.19553. The 2025 set was built on 2023 data.
Should I use the 2025 or the 2026 conversion factors?
Use the set for the year your activity data falls in. DESNZ says each year's factors are for use with activity data that falls entirely or mostly within that year, so activity in calendar 2025 uses the 2025 set even if the report is written in 2026. A financial year ending 31 March 2026 has nine of its twelve months in 2025, so it falls mostly within 2025.
When were the 2025 DEFRA conversion factors published?
DESNZ published the 2025 conversion factors on 10 June 2025, with a condensed set, a full set, a flat file, a methodology paper and a major changes report.
Is there a condensed set for 2025?
Yes. The 2025 release was the last to include one: DESNZ described it as "recommended for most, and new, users". The 2026 release has no condensed set, so the 2025 condensed workbook is still the right file for 2025 activity if you used it before.
Why is the 2026 electricity factor so much lower than 2025?
The 2026 factor is 0.13096 against 0.17700, about 26% lower. DESNZ attributes most of the fall to grid decarbonisation between 2023 and 2024 (about 16 percentage points), 3 points to the extra data year from 2024 to 2025, and 6 to 7 points to methodological changes. The 2026 set cut the data lag from two years to one, so no published set uses 2024 data.
What changed between the 2024 and 2025 factor sets?
DESNZ's 2025 major changes report lists the UK electricity factor down 15%, "primarily due to less natural gas use in power stations and increase in net imports of electricity"; air travel factors down 16% to 42% as load factors recovered from COVID-affected 2021 data; several HGV freight factors up because vehicles carried less per journey; water supply up 25%; and a 27% fall in some waste factors after a change in the assumed emissions from materials recovery facilities.
Is the Appendix 2 figure the 2025 electricity factor?
No. Appendix 2 of each methodology paper publishes an updated full time series for electricity, recalculated on that year's method, and its numbers differ from the published set. The 2025 paper's Appendix 2 shows 0.17721 for data year 2023; the factor in the 2025 set is the Table 9 figure, 0.17700.
Where can I download older DEFRA conversion factors?
Every annual set is kept on the GOV.UK collection page for UK government conversion factors for company reporting, so each prior year can be reported on its own factors.
Sources
Primary sources
Every figure, date and status on this page traces to the instrument’s owner. Secondary commentary is never the source for a number.
- DESNZGreenhouse gas reporting: conversion factors 2025
Published 10 June 2025: condensed set (for most users), full set, flat file, methodology, major changes.
- DESNZ2025 conversion factors methodology paper, ¶1.8 and Table 9
The activity-year rule and the data-year 2023 electricity row.
- DESNZ2025 conversion factors: major changes report, rows 1–40
What moved between the 2024 and 2025 sets, and DESNZ's reasons.
- DESNZConversion factors 2025: condensed set (Excel)
The last condensed set published.
- DESNZConversion factors 2025: full set (Excel)
- DESNZConversion factors 2025: flat file (Excel)
- DESNZ2026 conversion factors methodology paper, ¶¶1.10, 2.3, 3.7–3.8 and Table 9
Confirms the 2025 set used 2023 data, and that the condensed set ended in 2026.
- DESNZ2026 conversion factors: major changes report, row 17
The −16 / −3 / 6–7pp split of the 2025 → 2026 fall.
- DESNZUK government conversion factors for company reporting (collection)
Every annual set.
- GHG ProtocolA Corporate Accounting and Reporting Standard (revised edition, 2004)
Base-year recalculation, relevant when a series crosses the 2026 break.
- Department for Business and TradeUK SRS S2, ¶29(a)(iii) and ¶B29
Disclose the factors used and any change to them.
- legislation.gov.ukSI 2008/410 Schedule 7 (SECR), ¶¶16, 18, 20F, 20H
Methodology statement and prior-year comparatives.
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