What is it?

Different modes of transport cause different amounts of CO2 emissions. To effectively calculate individual mobility budgets and encourage sustainable mobility choices, data on mode-specific CO2 emissions is essential. This can be achieved through the application of emission factors.

How to calculate transport emissions

Emission factors are a measure of the amount of CO2 emissions emitted by travelling using a certain mode of transport. Typically, emission factors are calculated based on passenger-kilometres (for passenger transport) or tonne-kilometres (for transport of goods). For example, the emission factor for driving an average gasoline car in Austria is typically around 219 grams of CO2 per passenger-kilometre. For an average electric car it is 95 grams per passenger-kilometre.

There are direct and indirect transport emissions that are considered. Direct emissions refer to the emissions caused by the vehicle itself during its operation, such as tailpipe emissions from cars. Indirect emissions emerge in production and decommissioning of vehicles, the transport and production of fuel, and the construction of infrastructure. To assess the environmental impacts of different modes of transportation, both direct and indirect emissions are included in emission factors.


Variations in emission factors

Several socio-regional factors additionally influence the calculation of emission factors. National differences play a role, influenced by varying electricity mixes in different countries. Additionally, vehicle occupancy rates have a large impact; the more people travel in a single vehicle, the lower the emissions per person will be. Moreover, the type of energy used to power vehicles is a key factor. Electric cars using renewable energy, for example, are responsible for less carbon emissions compared to electric cars using mixed energy sources.

From transport emissions to mobility budgets

Data on transport emissions enables the calculation of individual mobility budgets, based on national emission targets. Through the understanding of mode-specific CO2 emissions and the calculation of individual mobility budgets, MyFairShare aims at enabling people to make informed decisions about their mobility choices.

Further Reading
  • Millonig, Alexandra. 2022. “Defining a Minimum Standard for Mobility,” MyFairShare Discussion Paper
  • Millonig, Alexandra, Christian Rudloff, Gerald Richter, Florian Lorenz, and Stefanie Peer. 2022. “Fair Mobility Budgets: A Concept for Achieving Climate Neutrality and Transport Equity.” Transportation Research Part D: Transport and Environment 103 (February): 103165.
  • Plank, Barbara, Willi Haas, and Dominik Wiedenhofer. n.d. “Towards Understanding Potential Rebounds and Problem-Shifts for MyFairShare.” MyFairShare Discussion Paper