How to calculate the CO2 emissions from the electricity consumption of your company?

A company wanting to calculate the CO2 emissions resulting from its electricity consumption must take into account the fuel mix, which differs depending on the type of chosen contract.

100% Green energy contract

  • The used production means don’t generate CO2 emissions and there will therefore be no CO2 emissions resulting from the electricity consumption of the company having opted for this type of contract.

‘Grey’ energy contract

  • To determine the CO2 emissions resulting from its electricity consumption, the company must multiply its electricity consumption (from fossil fuels) by a CO2 emission factor.
  • ENGIE recommends to use the official emission rate calculated yearly by AIB (Association of Issuing Bodies) for electricity produced in Belgium from fossil fuels.
  2022 : 144.27 g/kWh


Source : VREG -
The 2023 rate will be available at the end of May, beginning of June 2024. 


Only the percentage of electricity actually coming from fossil fuels must therefore be taken into consideration in the calculation (nuclear and renewable energy do not generate CO2 emissions). The fuel mix specific to the company's contract is available on each invoice (you will also find in appendix 1 the latest 'Grey' fuel mix by region).

A company consumed 500 000 KWh in 2022

The Fuel Mix of its electricity contract consists of:

  • 50 % fossil fuels
  • 40 % nuclear (CO2 emission = 0)
  • 10 % renewable (CO2 emission = 0)

CO2 emissions resulting from electricity consumption

  • 250 000 (50% of 100 000 KWh) * 144.27 = 36 067 500 g

In Flanders, each company can also check the origin of their electricity on the website of the VREG, based on their EAN number.