United Kingdom
UK Government GHG Conversion Factors
The UK Government's annual company-reporting factors: the broadest single catalogue Slate holds, and the default for UK organisations.
3,997
values in the 2026 release
1,705
cells DEFRA left blank, kept blank
AR5
GWP basis, already applied
659
Scope 3 catalogue entries built from it
Overview
The UK Government publishes a full set of greenhouse gas conversion factors every June for companies reporting under SECR and voluntary frameworks. It covers fuels, UK grid electricity, heat and steam, business travel, freight, hotel stays, homeworking, purchased materials and waste disposal, with upstream (well-to-tank) counterparts for most of them.
Every factor is published as kilograms of CO₂e per unit, already converted with IPCC AR5 100-year GWPs. Slate imports the machine-readable flat file, not the human-readable full set, and stores DEFRA's own row ID and spreadsheet row number against every value.
Market-based Scope 2 needs one more UK figure that this catalogue doesn't contain: the residual fuel mix. That comes from DESNZ's Fuel Mix Disclosure table and is imported as a separate one-row release.
At a glance
- Publisher
- Department for Energy Security and Net Zero (DESNZ) and DEFRA
- Code in Slate
UK_DEFRA- Covers
- Fuels, UK electricity, heat and steam, travel, freight, materials and waste
- Publishing schedule
- Annually, each June. The 2027 set is expected June 2027.
- Licence
- Open Government Licence v3.0
- Bulk download
- Permitted by the licence, from the publisher
Official files
These go straight to the publisher, never to a copy hosted by Slate. Where a page holds several files, the note names the exact one Slate imports.
- Get file
Data fileghg-conversion-factors-2026-flat-format-revised.xlsx
The file Slate imports. This is the revised v1.2 flat file, not the original.
- Get file
Data fileghg-conversion-factors-2026-full-set.xlsx
The same factors laid out by category for reading. Not imported.
- Open
Methodology2026 GHG conversion factors methodology report
How each factor was derived.
- Open
Changes report2026 major changes report
What moved since 2025. Several HGV categories were renamed.
- Get file
Data fileFuel mix disclosure data table 2025 to 2026 (PDF)
Source of the UK residual mix used for market-based Scope 2.
Releases in Slate
A release is one immutable published edition. Slate keeps the publisher's file unmodified, records its checksum, and selects a release by the date of each activity, so a 2022 record is always priced on 2022 data.
| Release | Edition | Valid for | Values | Blank | CO₂e | GWP basis | Status |
|---|---|---|---|---|---|---|---|
| UK DEFRA 2026 | flat-format-revised | 1 Jan 2026 – 31 Dec 2026 | 3,997 | 1,705 | Pre-calculated CO₂e | IPCC AR5 100yr | Active |
| UK DESNZ Fuel Mix Disclosure 2025/26 | residual-mix | 1 Apr 2025 – 31 Mar 2026 | 1 | — | Per-gas masses | — | Active |
What Slate uses it for
Stationary combustion
Fuel burned in boilers, furnaces and generators, from DEFRA's Fuels sheet.
Mobile combustion (fuel-based)
Litres or kilograms of road fuel. Road fuels use DEFRA's forecourt blend, as DEFRA's own guidance says: 2.075 kg CO₂e per litre for petrol against 2.35372 for pure mineral petrol, 12% apart.
UK grid electricity, four components
Generation (Scope 2, 0.13096 kg CO₂e/kWh), transmission and distribution losses (0.01299), well-to-tank of generation (0.03682) and well-to-tank of losses (0.00359). The last three are Scope 3 and each has its own row.
Purchased heat and steam
DEFRA's district heat figure, 0.17529 kg CO₂e/kWh.
Scope 3 catalogue
Business travel, freight, managed assets, hotel stays, homeworking, purchased materials and waste disposal: 659 catalogue entries generated from DEFRA's 1,023 Scope 3 activities. The 350 skipped are paths DEFRA lists without a value.
Market-based Scope 2 (UK)
The DESNZ residual mix, for electricity not covered by a supplier-specific or certificate-backed figure.
How Slate handles it
The decisions that change numbers, and why they were made the way they were.
- 01
Blank is never zero
DEFRA reissued the 2026 flat file as v1.2 because blank factors had been published as zeros. Slate imports the revised file, keeps all 1,705 blanks as blanks, and checks that count on every import. A zero factor would silently remove real emissions while looking like an answer.
- 02
CO₂e is already calculated
DEFRA's per-gas columns are kg CO₂e from that gas, not kg of the gas. Slate never applies a GWP set to them again, which would multiply methane by about 28 a second time.
- 03
AR5 is baked in
An organisation that switches to AR6 gets AR6 on its EPA and IPCC rows while its DEFRA rows stay AR5. Slate flags each affected row as mixing GWP vintages instead of hiding it.
- 04
No overseas electricity
Since 2026 DEFRA publishes UK grid factors only. Slate treats a non-UK site as outside DEFRA's coverage and moves to the next source in the organisation's chain. It never prices a Boston office on the UK grid.
- 05
Distance-based vehicles are not wired yet
DEFRA's 200 vehicle-distance rows are imported, but they classify vehicles by market segment and load, while Slate's vehicle list follows EPA's fuel-and-duty classes. Matching one to the other would be a guess that changes numbers, so fuel-based entry is the supported path for now.
Check a figure yourself
- 1
Open the 2026 factors page and download the flat file.
- 2
Find the row by the DEFRA ID shown in the record's provenance panel, or by its spreadsheet row number.
- 3
Compare the kg CO₂e value with the factor on the calculated record. They match to the last published digit.
Where to find the reference
Every calculated record in Slate has a provenance panel showing the release, the publisher's own row reference and the GWP set applied. See Calculated Emissions & Errors.
Licence and attribution
- Licence
- Open Government Licence v3.0
- Attribution
- Contains public sector information licensed under the Open Government Licence v3.0.