Emissions from domestic and international flights are calculated differently where the air travel data available allow. Calculation factors for short, medium and long-haul flights are taken from DEFRA’s Greenhouse Gas conversion factors for company reporting, available on the DEFRA website.
The Government Carbon Offsetting Fund (GCOF) uses the DEFRA greenhouse gas conversion factors for company reporting to calculate emissions from air travel per kilometre.
GCOF also employs a radiative forcing multiplier of two to account for the additional impacts of emissions at altitude. Figures are presented in the form of CO2e (equivalent). Air travel distances are reported in kilometres by individual GCOF participants.