Why the annual factor update matters more than most SMEs realise
Every year, the Department for Energy Security and Net Zero (DESNZ) publishes updated Greenhouse Gas (GHG) Conversion Factors. These are the official multipliers that turn raw consumption data into carbon dioxide equivalent (CO2e) figures. Kilowatt hours of electricity, litres of diesel, tonnes of refrigerant. All of it gets converted using these numbers.
Most businesses don't notice when the update drops. But if you're bidding for public sector contracts and your tender includes a Carbon Reduction Plan (CRP) under Procurement Policy Note 006, the year of the conversion factors you used isn't a minor detail. Procurement officers check it. Auditors check it.
A CRP that uses last year's factors for the current reporting period is, strictly speaking, out of compliance. That's enough for a CRP to be challenged during evaluation. In a competitive tender, that's a risk you don't want to take.
What changed in the 2025 factors
The 2025 DESNZ conversion factors came out in June 2025. A few things are worth paying attention to.
- Grid electricity: The emissions factor for UK grid electricity has kept falling, as more renewable capacity comes online. If you're a significant electricity user, your Scope 2 footprint for 2025 will likely be slightly lower than 2024, even if your consumption hasn't moved.
- Natural gas: There's been a modest revision to the natural gas combustion factor. Gas is still the main source of Scope 1 emissions for most office-based and light industrial SMEs, so even small changes here can shift your total materially if your premises run on gas heating.
- Refrigerants: Global warming potential values for refrigerants keep being refined in line with the latest IPCC assessments. If you've got commercial refrigeration, air conditioning, or any process using HFCs or other fluorinated gases, check whether the specific gases you use have been updated. Refrigerant leakage can represent a disproportionately large chunk of a small business's total footprint. Errors here matter.
- Transmission and distribution losses: The upstream factor for grid electricity, covering T&D losses, has also changed. It's easy to overlook but it affects your total Scope 2 figure under a location-based methodology.
These aren't sweeping methodological changes. The DESNZ factors get updated annually because the underlying data actually changes every year. Grid fuel mix, revised GWP values, updated supply chain emission intensities. The framework stays consistent. The numbers move.
Why factor vintage is a compliance issue, not just a technicality
PPN 006 requires Carbon Reduction Plans to follow the GHG Protocol and reference the current DESNZ conversion factors for the reporting period. That's not just best practice. It's part of the specification your CRP has to meet.
If you submitted a CRP in 2024 and you're reusing it for a 2025 tender without updating the factors, you're presenting figures built on superseded data. Depending on the contracting authority, that can mean:
- A compliance query during evaluation, with pressure to resubmit corrected figures fast
- A scoring penalty if the evaluation framework includes a factor-currency check
- In more rigorous procurements, disqualification of the CRP entirely
The real risk isn't a marginal difference in your CO2e total. It's that anything suggesting your CRP was put together carelessly, stale inputs, boilerplate text, out-of-date references, reflects on your overall approach to sustainability governance. Procurement panels do notice. It's the kind of thing that makes evaluators wonder what else wasn't checked.
What you need to do right now
Four steps. None of them are complicated.
- Check which factor year your current CRP references. If it cites 2024 factors, or if it was produced before June 2025, it needs reviewing.
- Recalculate any emission sources where the factor has changed. Electricity, natural gas, and refrigerants are most likely to have shifted meaningfully for a typical SME.
- Update the factor vintage declaration in your CRP. PPN 006 guidance expects you to state which factors you used and for which reporting period. Those two things need to match.
- Keep your source data. Procurement auditors can ask for the underlying consumption figures that support your CRP. Meter readings, invoices, refrigerant service logs. File them against the submission before you forget.
How CarbonVerified handles this automatically
Tracking an annual government publication, cross-referencing it against your carbon data, and recalculating your footprint is exactly the kind of admin that eats time SMEs don't have.
CarbonVerified gets updated to the current year's DESNZ factors as soon as they're published. When you log in and run your calculations, the platform's already using the correct figures. You don't need to download the DESNZ spreadsheet, find the right rows, or update anything manually. It's handled.
Your generated Carbon Reduction Plan also includes a clear statement of which factor year was applied and for which reporting period. That's what procurement teams want to see.
If you produced your CRP using an older version of the platform or a manual spreadsheet, now's a good time to run a fresh calculation and generate an updated document before your next submission.
Don't let a stale spreadsheet cost you a contract
The 2025 DESNZ conversion factors are published and in effect. Grid electricity intensity keeps falling. Natural gas and refrigerant factors have been revised. Any Carbon Reduction Plan relying on 2024 or earlier factors for a 2025 reporting period is technically outdated and carries real compliance risk in public sector procurement.
Keeping your CRP current isn't a big job. But it does need to happen every year, and it needs to happen before you submit your next tender. CarbonVerified takes care of the factor currency for you. If you're not using the platform yet, this is a practical reason to start.
Create or update your Carbon Reduction Plan at carbonverified.uk, compliant with the 2025 DESNZ conversion factors and ready to submit with your next public sector bid.
