Emission Factor Dictionary
The datasets behind every calculation — sources, regions, and how a factor is selected.
1. Summary
An emission factor is the number that turns your data into emissions — so much CO₂e per pound spent, or per kWh used. Carbon Passport does not make up its own. Every factor comes from official UK government data (BEIS/DEFRA), which we look up through a service called Climatiq, always set to the United Kingdom. The one exception is a Gold line, where your supplier has given you their own CO₂e figure and we use that directly instead.
2. Datasets in use
| Data set | Who publishes it | What we use it for | Country |
|---|---|---|---|
| UK government spend-based factors | UK Government (DESNZ / DEFRA), via Climatiq | Bronze lines — worked out from the amount spent | United Kingdom |
| UK government activity factors | UK Government (DEFRA), via Climatiq | Silver lines — worked out from actual usage (kWh, litres, kg, km) | United Kingdom |
| Your supplier's own CO₂e figure | The supplier, on a certificate | Gold lines — used exactly as given | Not applicable |
We always use the current published UK data at the moment of calculation. Every line we calculate stores the exact factor it used and where that factor came from — so even years later, you can find out precisely which version of the data sat behind any figure in your report.
3. Datasets we deliberately don't use
| Data set | Why we avoid it |
|---|---|
| EXIOBASE | It has no UK-specific figures, so it does not line up with UK reporting. |
| US EEIO / USEEIO | It is built for the United States and does not apply to UK reporting. |
| CEDA (as a default) | It used to get used as a catch-all. Our spend figures now come consistently from UK government data instead. |
This is applied across the whole platform: every spend-based lookup uses the BEIS/DEFRA UK data, so a UK figure is never quietly swapped for one from another country that happens to be easier to find.
3.1 If a line returns no emission factor
Sometimes a line cannot be calculated because there is no UK factor for the category it ended up in. When that happens we mark the line as failed and tell you why. We never quietly drop it, and we never quietly guess a number instead.
You can usually fix it yourself. Try these in order:
- Check the category first. Most of the time the factor is not really missing — the line has simply been put in the wrong category. Correct it in Review and run the calculation again.
- Add a quantity and a physical unit if the line is something measurable — kWh, litres, kg or km. This moves it onto the Silver, activity-based tier, which covers far more of the UK data than the spend-based Bronze tier does.
- Pin a specific activity to the line, if you already know which factor ought to apply.
- Give us your supplier's own CO₂e figure from a certificate. This skips factor lookup entirely and is the most accurate option there is.
If a line still will not calculate after all four, then the category genuinely has no UK factor available. Contact support rather than editing the line any further — fixing it is a change we need to make at our end, not something you can solve on the line itself.
4. How a factor is selected per line
- Gold — your supplier gave you a CO₂e figure, so we use it directly and look nothing up.
- Silver — you gave us a quantity and unit, so we use a UK usage-based factor (DEFRA).
- Bronze — all we have is an amount, so we use a UK spend-based factor for that type of spending (BEIS/DEFRA).
5. Audit trail
For every line we calculate, we record:
- Which data set it came from, and who published it.
- The exact name of the factor, its value and its unit.
- The country the factor applied to.
- Which of the three tiers was used, and why.
- The full response we received, kept word for word.
This means the exact factor behind any figure can always be recovered from your own records, without relying on this page.