Calculating tonnes of CO2 equivalent for the CO2 Performance Ladder
You calculate a tonne of CO2 equivalent (CO2e) by multiplying your consumption by an emission factor. If you calculate in kilograms, divide the result by 1,000. For the CO2 Performance Ladder, you use the factors from co2emissiefactoren.nl . For fuels and transport, use the Well-to-Wheel (WTW) column, which includes extraction and production of the fuel. Under handbook 3.1, you must quantify CO2 in tonnes of CO2. You may report other greenhouse gases as CO2e, but this is not yet mandatory. The full explanation of the calculation method is on calculating your CO2 footprint.
The factors in this article come from the 2026 list on co2emissiefactoren.nl, read on 28 October 2026. They change every year. For your own emissions inventory, always use the factor for the year you report on.
This page follows handbook 3.1. Handbook 4.0 (published on 14 January 2025) may have different rules for greenhouse gases. Check this in handbook 4.0 if you switch to it. Audits under 3.1 can still take place until 14 January 2027. See the transition scheme .
What is a CO2 equivalent?
Not every greenhouse gas has the same effect on the climate. Methane and nitrous oxide are more potent than CO2. To add them together, you convert them into the amount of CO2 that has the same effect. That result is called CO2 equivalent.
In practice, it is simpler for most companies. Fuel and energy mainly produce CO2. The CO2 equivalent is then equal to the CO2 emissions. The difference only becomes large with refrigerants and some industrial processes.
What does handbook 3.1 say?
The handbook is precise here. The requirement for the emissions inventory (requirement 3.A.1) states that reporting CO2 emissions is mandatory, quantified in tonnes of CO2. For other direct greenhouse gases, you may report them, provided you list them separately and convert each gas into tonnes of CO2 equivalent.
The handbook describes itself as the last version in which reporting other greenhouse gases is not yet mandatory. Organisations are encouraged to report them anyway. To choose between 3.1 and 4.0, see levels and rungs.
The calculation formula
The basis is always the same:
Emissions in kg CO2 = consumption × emission factor
Emissions in tonnes CO2 = emissions in kg ÷ 1,000
You find the emission factor on co2emissiefactoren.nl, per fuel or energy carrier, with the unit stated. Pay attention to the unit. You cannot convert a factor per litre using cubic metres. Check that your consumption is in the same unit as the factor.
Step by step: an example
A fictional construction company used 4,000 litres of diesel in one year, according to fuel card statements. The table gives the factor per litre. The 2026 list gives a WTW factor of 3.251 kg CO2e per litre for pump diesel (line “Diesel B7”). That is more than the exhaust emissions alone, which are 2.462 kg per litre. Biogenic emissions are in a separate column. Check on the site which line applies to your fuel.
| Step | Calculation | Result |
|---|---|---|
| 1. Record consumption | 4,000 litres of diesel | 4,000 litres |
| 2. Look up the factor | Diesel B7, WTW, 2026 list | 3.251 kg per litre |
| 3. Multiply | 4,000 × 3.251 | 13,004 kg |
| 4. Convert to tonnes | 13,004 ÷ 1,000 | 13.0 tonnes CO2 |
You calculate each energy flow this way. Then you add the results per scope. Scope 1 covers your own fuel and gas use. Scope 2 covers purchased electricity. See scope 1, 2 and 3 emissions for the classification.
A table that satisfies the auditor
The auditor wants to see how you get from consumption to tonnes, without having to calculate it themselves. Use a fixed table with these columns. The gas and electricity consumption in the example are fictional, but the factors are not:
| Energy carrier | Source of consumption | Quantity | Unit | Factor (WTW) | Source of factor | Emissions (tonnes CO2) |
|---|---|---|---|---|---|---|
| Diesel B7 | Fuel card | 4,000 | litres | 3.251 | 2026 list, vehicle fuels | 13.0 |
| Natural gas | Annual statement | 5,000 | Nm3 | 2.134 | 2026 list, fuels for energy generation | 10.7 |
| Grey electricity | Annual statement | 20,000 | kWh | 0.483 | 2026 list, electricity | 9.7 |
Always record the source of the factor. The handbook also requires this: any deviation from the official factors must be justified and submitted to the ladder CI.
What applies to green electricity and gas?
Green electricity and green gas receive a lower factor, but only with evidence. The handbook names guarantees of origin (GvO) as a condition. For green gas, you show the quantity with withdrawal statements from Vertogas (the Dutch green gas registry), or with an invoice plus a statement from the supplier. For green electricity, the handbook requires three things: GvOs issued by CertiQ (the Dutch issuer of guarantees of origin), a verifiable source (wind, water, sun or biomass), and an origin in the Netherlands or in a country that deducts the export of green electricity in its reporting to the European Commission. Without that deduction, the ladder calculates imported GvOs using the grey electricity factor.
If the origin of your electricity is unknown, use grey electricity. The line “electricity (unknown)” in the list may not be used according to the handbook. Green electricity from biomass also receives the grey electricity factor, unless the supplier can justify a different value.
Common mistakes
Wrong unit. Litres of diesel divided by cubic metres of gas gives a result that does not make sense. Check the unit of the factor before you calculate.
The wrong type of factor. For fuels, use the WTW column. The TTW column (Tank-to-Wheel, only exhaust emissions) gives too low a result, because extraction and production of the fuel are missing. For diesel B7, the difference is 3.251 against 2.462 kg per litre.
No source reference. A number without a source is not evidence for the auditor. Note the source and the year of the factor.
Green electricity without evidence. A low factor for green electricity without guarantees of origin will be removed during the assessment.
Forgetting recalculation. If the calculation method behind a factor changes, you recalculate the base year and document that. If the factor changes due to technological progress or market conditions, you do not need to. These rules are in section 5.2.3 of the handbook.
Multiple fuels and locations
If you have several locations or vehicle types, calculate separately per location and per fuel. Then add the results together. This makes it easier to find a deviation: if the total for one location is noticeably high, you can see straight away where to look.
Use the same factor for the same fuel within one year. Different factors for the same item in the same year cause confusion during the assessment.
What does the auditor want to see?
- An emissions inventory showing, per energy carrier, the consumption, the factor, the source and the emissions in tonnes of CO2.
- A reference to the version or year of the factors.
- Justification for each deviation from the official factors.
- Evidence for green electricity or green gas, if you use a lower factor for them.
- A check that the results per scope match the invoices.
Next step
With the tonnes of CO2, you can build the emissions inventory and set your reduction target. For that, read calculating your CO2 footprint for the full method. To prepare for the external audit, use the checklist.