How do you calculate how much carbon emissions I saved using FAIRTIQ?
We calculate your carbon emissions based on a national baseline of the country you travelled in. We then deduct the car emissions from the public transport emissions to come up with the amount of CO2 that you saved. To calculate the time period required to absorb the difference between these two CO2 emissions, we divide the saved CO2 by the absorption rate of a tree.
Here’s an example to illustrate our approach:
So far this year Lisa has used the FAIRTIQ app to travel in Switzerland between Bern and Zurich (95km one way) on a train. She did this trip twice meaning she did a total of 380 km.
To calculate the CO2 emissions for the train we multiply 380 km * 8.43 (Rail CO2 Emissions rate in Switzerland, see reference section below). The result is approximately 3.2 kgs of CO2 emitted.
To calculate the CO2 emissions saving, we then approximate the CO2 emissions made using a car (Car CO2 Emissions rate in Switzerland = 197.23) over the same distance. The result is approximately 75 kgs of CO2. Hence, the CO2 emissions saving is (75 - 3.2 kg) 71.8 kgs of CO2.
To calculate the time required for a tree to absorb the extra CO2 that would have been emitted by a car over the public transport means (71.8 kgs of CO2), we divide the extra amount by the absorption rate of an average tree (approx. 22 kgs per year). The time required to absorb the amount is approx. 3 years and 3 months.
So it would take a single tree approximately 3 years and 3 months to absorb the CO2 that Lisa would have emitted if she had rather chosen to take the car instead of the train in her 2 return trips from Bern to Zurich!
References
- Vehicle CO2 Emissions: The values we use are derived from mobitool-Faktoren v2.0.2, https://www.mobitool.ch/de/tools/mobitool-faktoren-25.html?tag=18
- Tree absorption rate: We approximate the tree absorption rate as 22 kgs per year, according to https://en.wikipedia.org/wiki/Deforestation_and_climate_change#Reforestation