ADEME Carbon Base: how to read and use
emission factors.

What is the ADEME Base Empreinte

The Base Empreinte (formerly Base Carbone) is a public, free database maintained by ADEME, the French Agency for Ecological Transition. It contains thousands of emission factors covering energy, transport, food, materials, services, waste, and many other categories.

Each emission factor expresses the quantity of greenhouse gas (in kgCO₂ equivalent) associated with one unit of activity: one kilowatt-hour of electricity, one kilometer driven by car, one euro spent in a given sector, one tonne of waste incinerated.

It is the reference database for any carbon footprint assessment carried out in France. Consulting firms use it, market platforms use it, and Oakbon uses it. Using other factors without justification weakens the credibility of your report with your client.

Monetary ratio vs physical factor: the essential distinction

The Base Empreinte contains two types of factors, and confusing them is the most common mistake among non-experts.

Monetary ratios (kgCO₂e per euro) are sector averages. They estimate emissions based on the amount spent. Each business sector, identified by its NAF code, has a specific ratio. For example, one euro spent in the steel industry generates more CO₂ than one euro spent in IT consulting.

Advantage: they can be used immediately from your accounting records, without collecting additional data. Drawback: they give a sector average, not the specific reality of your supplier or your consumption.

Physical factors (kgCO₂e per kWh, per km, per tonne) are technical values. They are much more precise because they measure actual activity, not its cost. The factor for French electricity (about 0.052 kgCO₂e/kWh) reflects the real energy mix of the grid, which is mainly nuclear.

Advantage: much higher precision. Drawback: you need physical data (kWh consumed, km traveled, tonnes of materials purchased), which is not always available.

Best practice: start with monetary ratios (your accounting records are enough), then progressively replace them with physical factors for the items where you have the data. This is exactly Oakbon’s approach: monetary calculation by default, physical refinement through the guided questionnaire.

How to find the right factor for your sector

The Base Empreinte is available at base-empreinte.ademe.fr. The interface is functional but dense. Here is how to navigate it.

For monetary ratios: search for “ratios monétaires” in the search bar, or browse the “Ratios monétaires” category. Factors are classified by two-digit NAF code (division), then refined by four-digit NAF code (class). The more precise the code, the better the ratio.

For physical factors: search by activity category. For example, “électricité France” for energy, “transport routier” for freight, “acier” for materials. Each factor is documented with its source, methodology, uncertainty, and last update date.

Watch the scope: each ADEME factor has a specific scope (upstream, combustion, upstream+combustion). For a Scope 3 assessment, you generally use “upstream+combustion” factors (also called “full life cycle”). Always check the scope before applying a factor.

The five common pitfalls to avoid

Pitfall 1: using an “all sectors combined” monetary ratio. Average ratios exist but are very imprecise. Always take the most sector-specific ratio possible. The difference between the “general manufacturing industry” ratio and the “mechanical parts manufacturing” ratio can be a factor of 2.

Pitfall 2: confusing net and gross amounts. ADEME monetary ratios apply to amounts excluding tax (net of VAT). If you use gross (VAT-included) amounts, your emissions will be overestimated by about 20%.

Pitfall 3: forgetting uncertainty. Every ADEME factor has documented uncertainty (often ±30 to ±50% for monetary ratios). This uncertainty must appear in your report — it is a requirement of the GHG Protocol and of ESRS E1. A report that displays “247.3 tCO₂e” without mentioning uncertainty lacks rigor.

Pitfall 4: using outdated factors. The Base Empreinte is updated annually. A 2020 monetary ratio can be significantly different from the 2024 ratio. Always check the version of the factor you are using, and reference it in the report. Oakbon systematically uses the latest available version and references it in every generated report.

Pitfall 5: double-counting emissions. Some accounting entries cover expenses already accounted for elsewhere. For example, rent (account 613) sometimes includes energy charges, which are also in account 6061. The PCG → GHG mapping must be done carefully to avoid duplicates.

In summary: your ADEME factors checklist

1. Use the most precise NAF-code ADEME monetary ratios possible for your baseline calculation.
2. Replace them with physical factors when you have the data (energy in kWh, transport in km).
3. Apply ratios to net (excluding VAT) amounts, never gross amounts.
4. Check the scope of each factor (upstream, combustion, full life cycle).
5. Document the version of the Base Empreinte used and the associated uncertainty.
6. Update your factors every year with the new ADEME version.

Ready to calculate your carbon footprint?

Oakbon automates the calculation of your Scope 3 emissions from your accounting data. Report in under 2 hours.

From €69/month · No commitment