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Calculation methodology

How is the CO2e impact of my trip calculated?
Greentripper is based on 2 main methodologies:
  • The Bilan Carbone © approach of ADEME, which stands for Agence de l’Environnement et de la Maîtrise de L’Energie, i.e. the Environment and Energy Management Agency in France. This semi-public organisation is recognised worldwide for their greenhouse gas emission calculation tool/method known by the name of Bilan Carbone ©.
  • DEFRA, The Department for Environment Food & Rural Affairs (GOV.UK) which provide conversion factors allowing organizations and individuals to calculate greenhouse gas (GHG) emissions from a range of activities, including energy use, water consumption, waste disposal, recycling and transport activities. It is a standard compliant to GHG (Greenhouse Gas) Protocol.

For all means of transport the following data are taken into account:
  • The travel distance or the duration,
  • The number of passengers for the public transport
  • For car transport, the fuel used and the energy mix in the case of an electric car.
How much does it cost?
The further you go, the more CO2ee you emit. The cost depends on your destination and the transport used.

Use our carbon footprint calculator to find out the carbon footprint of your trip and try to reduce it by choosing a less emissive means of transport (train instead of plane).

Once you have reduced your footprint as much as possible, you can contribute to climate projects. The CO2e contribution represents a small part of the cost of your trip. It's a small gesture that has a concrete impact. If you travel, it is better to contribute to climate projects than to do nothing.

Some examples for air travel:
  • Brussels-Barcelona (round trip - economy class): +-€ 10 incl. VAT/per person for +-400 kg of CO2 equivalent
  • Brussels-Lima (round trip - class): +-€ 90 incl. VAT/per person for 3.88 tons of CO2 equivalent
  • Brussels-Kigali (round trip - economy class): +-55 € incl. VAT/per person for 2.3 tons of CO2 equivalent.
Why are the emissions indicated on the air ticket not the same as those calculated on Greentripper.org?
Greentripper calculates the total environmental impact of travels. If we want to calculate the complete impact of travels, we have to take into account the CO2-equivalent emissions, but also other factors such as the radiative forcing (or high altitude) effect, for example for air travels.
How much CO2e does an aeroplane emit?
We base our Emission factors for flight travels on 2 official methodologies: Greenhouse gas reporting by DEFRA (Department for Environment, Food & Rural Affairs - GOV.UK) & Bilan Carbone by ADEME. Every 6 months, we follow the evolution of the Emission Factors of these 2 methodologies and we adapt them on our calculator if necessary.

In 2022, according to DEFRA, an airplane emits between 0.164 and 0.273 kg of CO2 equivalent per passenger-km in Economy class. According to Ademe, for planes with more than 100 seats, an airplane emits between 0.152 and 0.305 kg of CO2 equivalent per passenger-km in Economy class

What is taken into account in these emission factors?
  • The CO2e impact of burning kerosene
  • The impact of radiative forcing, it multiplies by +- 2 the impact of the kerosene combustion.
  • The WTT impact (Well-to-tank impact) which corresponds to the CO2e impact to produce kerosene
  • The class used by the traveller: Economy, Premium Economy, Business or First.
  • We take into account the different greenhouse gases (CO2, but also other greenhouse gases such as CH4 and N2O) which are converted into a CO2-equivalent. That is why we speak about CO2-equivalents (CO2e) and not CO2.
Why is there a difference between the price of Greentripper and the price of other calculators?
The differences are explained by the calculation method used and the type of projects supported.

At Greentripper, we use two official methodologies: ADEME's Bilan Carbone ©, where each emission factor is provided with an uncertainty of 20% to 50% & DEFRA's Greenhouse gas reporting (Department for Environment, Food & Rural Affairs - GOV.UK).

For air travel, on www.greentripper.org, we want to give you the total impact of your travel, we take into account the radiative forcing effect which is not taken into account by all calculators. The price per tonne of CO2e also depends on the type of project we support. Indeed, the price of a climate project depends on different factors: the country in which the project is developed, the technology used, the size of the project (how many tons of CO2e can be reduced or avoided each year), the number of stakeholders that make the project possible (NGOs, project developers, consultants, ...), the type of label that certifies, among other things, the transparency, the impact on the Sustainable Development Goals and the additionality of the project.