Creating your own emission factor
Record a value that exists in no public database, and reuse it afterwards.
Published on 12/08/2026
Sometimes no public database holds the value you need: a supplier has sent you the actual footprint of the part they deliver, a consultancy has studied your process, or your electricity is covered by a specific certificate. In those cases, picking a "roughly similar" factor means throwing away the best data you have.
The platform therefore lets you create your own factor, right where you need it.
How to do it
The steps are the same in the carbon inventory and in a product LCA, since the factor picker is the same window.
- Open an emission entry or an LCA line, as usual.
- Search for your factor. If nothing fits, click "Create my own factor", below the results.
- Fill in four fields: the label (the one you will read six months from now: the term you just searched for is carried over automatically), the value in kgCO2e, the unit it refers to (per kilogram, per kWh, per piece, per kilometre) and the source, meaning who provides this figure and when.
- Confirm: the factor is saved and selected for the current line. All that is left is the quantity.
What happens to it next
Your factor joins the factor database, exactly like the others. In practice:
- it shows up in search during your next entries: you never type it twice;
- it carries the source "Mes facteurs", which makes a house figure instantly distinguishable from a public-database one;
- it is visible to you alone. A value passed on by a supplier is sensitive: no other organisation on the platform sees it, neither in search nor in the details of a shared LCA.
Unit and source are not paperwork
The unit drives the calculation. A line total is the quantity you enter multiplied by the factor: a "per piece" factor used against a number of kilograms produces a wrong result, with no error message. Record the unit exactly as your supplier wrote it.
The source is what makes the figure worth anything. A house factor without provenance becomes unusable the day someone asks where it comes from: during an audit, a check by a client maison, or simply next year when you must decide whether it still holds. Write down who provided it and when, for example "supplier data sheet, Duval, March 2026".
A special case: the value zero
A value of zero is accepted: it describes a genuinely neutralised flow, such as electricity covered by a certificate. That is information, not missing data.
A negative value is refused. An avoided or sequestered emission does not belong in a negative factor, where it would quietly vanish into a sum: it is declared as a separate item, so it can be read, discussed and removed if contested.
When not to create a factor
If your data is a personal estimate rather than a measurement, you are better off taking a public factor and noting it as an approximation: at least the source is traceable and comparable. A house factor makes sense when you hold a measured value that exists nowhere else, not to round a figure to your liking.