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Calculation methodology

Calculation of Emissions Related to Travel
Greentripper conducts regular reviews of its emission factors (EF), ensuring that they are updated at least once a year to maintain the accuracy of their CO2e calculator and in line with the latest scientific findings for greenhouse gas estimation.

These emission factors are determined through calculations based on:
  • The passenger impact on the plane, the coach bus, the boat and the train.
  • The vehicle impact for the cars, camper and the two-wheelers.
  • The visitors impact for accommodation and meeting rooms.
  • The travellers impact for their activities and alimentation.

Greentripper relies primarily on two recognized methodologies:
  • The Bilan Carbone © approach of ADEME , the Environment and Energy Management Agency in France. This semi-public organization is recognized worldwide for their greenhouse gas emission calculation tool/method known by the name of Bilan Carbone ©. The ADEME is one of the pioneers for the calculation of greenhouse gases and the conversion into CO2-equivalent in accordance with the Global Warming Potential (GWP), i.e. the contribution to the greenhouse effect.
  • The Greenhouse gas reporting of the Government UK which is called DEFRA or BEIS methodology, produced by AEA for DECC and Defra. There are 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. The emission results have a high-level of completeness giving the CO2-equivalent impact, the separate GHGs, Separate scopes, Direct and Indirect emissions.

The carbon footprint assessments conducted with the Greentripper tool provide you with an overview of your impact on Greenhouse Gas (GHG) emissions in CO2-equivalent. These results aim to offer a general understanding, recognizing that none of the existing methodologies can ensure absolute accuracy, allowing for a margin of uncertainty in the assessment.
Greentripper uses DEFRA's methodology to calculate plane travel carbon footprint (kg CO2e.passenger.km). It considers travel classes, flight distances, stopovers, ‘Well-to-Tank’ impact and the radiative forcing impact.

The various greenhouse gases are converted to CO2-equivalent. The emission factors are kept up-to-date and reviewed at least annually.
The GHG taken into account concerns:
  • Manufacture of the vehicle, with the EF source being the ‘Base Carbone® 2022’ (kg CO2.vehicle.km).
  • Well to tank (WTT):
    • For Gazole, essence & LPG fuel, the source of EF is ‘Base Carbone® 2022’ (kg CO2.vehicle.km).
    • For electric and plug-in hybrid vehicles, the EF is based on the country and its energetic mix (IEA database).
    • Combustion of fuel: For combustion vehicles, the combustion of fuel depends on the consumption (liters of fuel per 100 km). The source of EF is Bilan Carbone ® (kg CO2e per liter).
    • Taxis follow DEFRA's methodology for combustion and Well-to-Tank impacts.

To calculate CO2e emissions, users provide:
  • Fuel type (Diesel, Gasoline, LPG, electric, hybrid, mild hybrid, plug-in hybrid, or taxi)
  • For electric/plug-in hybrids: electricity source (country & green/grey)
  • Fuel consumption or car model for an average consumption (small, medium, or large) in l/100 km or kWh/100 km
  • Distance travelled (km)
Greentripper classifies trains (Regional, Night, main lines & High-speed, Eurostar, Thalys, Railjet ÖBB, ICE) with specific CO2e emission factors (EF) in g CO2e.passenger.km. The EFs used come from ADEME's Base Empreinte ® for regional, main lines and high-speed trains, and specific emission factors from companies for private high-speed trains. Updates come from DEFRA, SNCF, Eurostar, and scientific studies.

To calculate, users provide distance or travel time, train type, country, and passengers.
Tram & Metro
For Metro and Tram, Greentripper uses the carbon calculation methodology of STIB (Brussels public transport). The emission factors are in the same order of magnitude of the DEFRA factors (in g CO2 per passenger.km). To calculate CO2e emissions, data needed includes distance (in km) and the number of people.
Bus & Coach
Greentripper uses DEFRA for (coach) bus emission factors (kg CO2e.passenger.km), considering direct and well-to-tank emissions. Users provide the type of bus, the number of people, the distance, and specify 'one way' or 'round trip'.

Upon request, Greentripper also offers more detailed calculations based on vehicle occupancy rates (e.g., in cases of vehicle privatization).
Greentripper classifies vans and campervans into 3 types of vehicles (based on real data from campervan rental companies). For emissions from fuel consumption (kg CO2e per liter), indirect upstream emissions (kg CO2.vehicle.km), and the vehicle manufacturing impact (kg CO2.vehicle.km), we use emission factors from the 'Base Empreinte ® 2023'. Users provide the distance and the type of campervan.
  • Ferry Cargo (Ferries which carry both passengers as well as freight - focus on freight) : Use of DEFRA methodology, differentiating impacts for foot and car passengers. Accounts for WTT and relies on Brittany Ferries' average speed. Users provide type of travel, number of travellers, vehicles (if any) and travel time or distance.
  • Ferry Passengers (with main objective to transport passengers). Greentripper is here based on studies of Jonas Åkerman (from Stockholm University). Users provide type of travel, number of travellers and travel time or distance.
Greentripper developed its own calculation for cruise emissions based on surveys, articles, and a Life Cycle Assessment analysis (author: Morten Simonsen - Western Norway Research Institution). It includes environmental impact during navigation and 'hotel mode' impact, representing in average 30% of total emissions.

Users provide cruise days and number of travellers to calculate CO2e emissions.
On demand, Greentripper proposes also more detailed calculations based on cruise boat size, real travel distances & occupancy.
Greentripper proposes the calculation of the environmental impact for various types of accommodations (kg CO2e), including Hotels (2 to 5 stars), Bed & Breakfast, seasonal locations, and second residences. For hotels, it relies on GreenView, which takes into account the energy mix by country. For other types of accommodation, it relies on estimates from ADEME. For eco-labeled accommodations with a recognized ecological approach, Greentripper estimates a 20% reduction in carbon footprint per night compared to the same accommodation without reduction efforts. Users provide details such as the type of accommodation, the country (for the energy mix), and the number of rooms occupied per night to calculate CO2e emissions.
Greentripper relies on various sources for the carbon footprint of the activities :
  • For motorized activities (helicopter, scenic flights, safari & motorized boat), we rely on Emission Factor (kg CO2e. fuel liter) from Base empreinte® 2023. The average consumption taken into account comes from various blogs & articles.
  • The impact of a day at a festival is based on a study of the climate company CO2logic.
  • Impact of a ski day comes from a study made by ‘Utopies’, a Consulting company
  • Impact of a hot air balloon was calculated by the climate expert ‘Sami’
  • For non-motorized activities & cultural activities, we consider a CO2e impact equals to zero. If these activities require a motorized locomotion, this has to be considered apart. Examples: go snorkeling but a small motorized boat is needed to reach a specific place) or go to the museum by coach bus.
For the carbon footprint of food, Greentripper relies on Emission Factors from ‘Base Empreinte® 2023‘.
Traveller selects the general type of meal (vegetarian, varied, red meat, fish...), the number of days & the number of people.