Defra conversion factors, matched to the right year
Emissa calculates with the official UK Government greenhouse gas conversion factors. Each annual release is imported from gov.uk automatically, kept as its own versioned dataset, and applied to activity dated in its own year — so a new release never rewrites last year's figures.
Every release, imported for you
The UK Government publishes its conversion factors for company reporting once a year, and sometimes revises them. Nobody has to watch for that or copy a spreadsheet in.
Detected on gov.uk
The platform checks gov.uk for new releases and revisions on a schedule.
Imported as a versioned dataset
Each release is read from the official flat-format file and stored as a dataset with its year, version and source.
Published to every client
New datasets are added alongside the old ones, never in place of them, so publishing changes no existing figure.
Each year's activity, each year's factors
A bill dated in 2025 is calculated with the 2025 factors, and one dated in 2026 with the 2026 factors — so a reporting year that straddles two releases uses both, line by line. Earlier years' datasets, and the results calculated with them, are never modified by a new release.
Releases are synced back to 2023, the first year published as a flat-format spreadsheet, so historic periods get their own year's factors. Earlier years can be uploaded by hand.
If a line in an open period was calculated with a factor from the wrong year, or with an older revision, it is moved to its own year's release and recalculated. The earlier result is superseded, not overwritten. Locked and restated periods are left alone, and so are supplier and custom factors.
The source is the UK Government's greenhouse gas conversion factors for company reporting collection on gov.uk.
When another factor is the right one
Defra's factors are the default, not the only option. Every alternative carries its source, so a reader can see which factor a line used and why.
Sites outside the UK
Add a country's published electricity factor with its source once, and bills for sites in that country take it automatically.
Market-based Scope 2
Set a market-based factor, such as your supplier's tariff or a residual mix, and electricity is reported both location- and market-based.
Supplier-specific Scope 3
Reviewed submissions from the supplier portal become supplier-specific factors with full provenance.
Well-to-tank from the same dataset, not a percentage
Each fuel and electricity line derives its upstream Scope 3 category 3 lines — well-to-tank and, for electricity, transmission and distribution losses — from the same quantity against the upstream factor in the same dataset and year. Edit or delete the source line and they follow.
Common questions
Which conversion factors does Emissa use?
The official UK Government (Defra) greenhouse gas conversion factors for company reporting, published each year on gov.uk. Every release is imported as a versioned dataset — nothing is hard-coded and nothing is invented.
Which year's factors apply to our data?
The release for the year the activity is dated in: 2025 activity is calculated with the 2025 factors, 2026 activity with the 2026 factors. Publishing a new release never changes a figure calculated with an earlier one.
What happens when a release is revised?
The revision is imported as the next version of that year's dataset. Lines in open periods move to it and are recalculated, with the earlier result superseded rather than overwritten. Locked and restated periods are not touched.
Can we report earlier years?
Yes. Releases are synced back to 2023, the first year published as a flat-format spreadsheet, so historic periods are calculated with their own year's factors. Earlier years can be uploaded by hand.
Can we use factors other than Defra's?
Yes, where they are the right factor: a country's published electricity factor for sites outside the UK, a market-based factor such as a supplier tariff for Scope 2, and supplier-specific factors from reviewed supplier submissions for Scope 3. Each one carries its source.
More of the platform
Scope 1 and 2 emissions
Gas, fuel, refrigerant and electricity bills turned into ledger lines, with Scope 2 both location- and market-based.
Scope 3 emissions
All fifteen categories, from supplier data, spend, travel and surveys — with the working on every line.
UK SRS reporting
A disclosure workbook on the four pillars, filled from the ledger, with reports and an audit pack.
Carbon audit trail
Every figure walked back to its factor version, calculation trace and source document.
Biodiversity initiatives
Site-by-site actions on one map, linked into pollinator highways and reported by client or region.
The whole platform
Measure, report and reduce: how the ledger, the methodology statement and the models fit together.
See it with your own data
A demo takes half an hour — bring a handful of real bills and watch them become an auditable ledger.
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