DEFRA Emission Factors

The DEFRA emission factors (also published by DESNZ) are the UK government's official carbon conversion values, used to translate activity data—like fuel use, electricity, travel, or waste—into greenhouse gas emissions (typically in CO₂e). Updated annually (latest in June 2025), they cover Scope 1, Scope 2, and several Scope 3 categories and serve as critical tools for accurate emissions reporting under frameworks like SECR and CDP.

1. What exactly do these factors do?

They convert everyday activities—fuel burned, miles travelled, energy used—into estimated greenhouse gas emissions you can report.

2. How often are they updated?

Annually—usually published around June/July. The 2025 version became available on 10 June 2025.

3. Which emission types are included?

• Scope 1: Direct emissions from fuels, company vehicles, refrigerants.
• Scope 2: Purchased electricity, heat, steam.
• Scope 3: Includes upstream/downstream activities like water, waste, travel, freight.

4. Do they cover UK only?

Primarily UK-focused, but many factors—like air travel—are used globally by international SMEs.

5. Why are they important for SMEs?

They ensure your emissions reporting is consistent, credible, and aligned with regulatory standards and investor expectations.

6. Where can I access them?

Available via GOV.UK, typically as downloadable Excel files (condensed, full, or flat-file versions depending on your needs).

7. Any notable updates recently?

Yes—2024 saw significant tweaks: PHEV emissions factors were adjusted, biodiesel (HVO) jumped, water supply/treatment factors dropped, and paper and transport values were revised.

8. How do they affect my emissions figures?

New factors may increase or decrease your emissions total—even if your actual activities haven't changed—so year-on-year comparison requires caution.

9. How should SMEs use them?

Align your data collection with factor publication year. Use the right version for the right reporting period, and consistently apply it across years for comparability.

10. What if my data spans multiple years?

Use the factor version matching each activity’s calendar year. When activity dates overlap, you may need to prorate data or use an average—ensuring transparent notes in your reporting.

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