There are many factors that determine your carbon footprint, but the main ones are:
- Where you live
- Lifestyle aspects
- Diet
- How you get around
- How your house is powered
- How many flights you take
We ask you for some information on each the above, and from this are able to estimate your monthly carbon footprint.
Baseline: Where you live
We start with asking you in which country you reside. We do this because the country you live in has the single biggest influence on your overall carbon footprint. A person living in Australia has a bigger footprint than a person with an identical lifestyle and diet living in, for example, Portugal. This is mostly because of the difference in each country's energy mix: Portugal's energy mix has a bigger share of renewables (wind, solar).
The data we use is the most recent available, from 2019, and is sourced fromOur World in Data. Check out the map above to see how countries differ.
The amount of tonnes for the country you live in becomes your baseline carbon footprint.
Adjustments based on your lifestyle
Next we ask you about your typical diet, how you get around, and how you power your home. Based on your selection, for each of these categories we assign your answer a score between 0 and 100.
A score of 50, the default, is considered average, and causes no change to your estimated footprint. A score of under 50 means your estimated footprint is reduced, and a score over 50 means your estimaed footprint is increased. The exact amount of tonnes your footprint is reduced or increased is different for each category:
Adjustment for diet
The carbon footprint adjustment values for diet are calculated based on multiple sources of information, with the main sources beingProject Drawdown's research on diet,Environmental Impacts of Foodfrom Our World in Data, andThe role of trade in the greenhouse gas footprints of EU diets, Vilma Sandström et al.
Points | Roughly corresponds to | Footprint adjustment in tonnes |
---|
0 | Vegan | -1.07 |
25 | Vegetarian | -0.54 |
50 | Average | 0 |
75 | No beef | +0.54 |
100 | Only meat | +1.07 |
Adjustment for transport
For transport, which doesn't include flights (they are a separate category in themselves, see below), we focused on what for most people is by far the most common journey they take in a year: their commute. We took data on CO2emitted per kilometre for cars (all fuel types including hybrid and electric) and for public trains and buses from theEuropean Environment Agency. We then looked at commute time information from theSixth European Working Conditions Surveyas well asTrends in Commuting Time of European Workers: A Cross-Country Analysis. Next, we worked out average car and bus speeds in peak times fromEU Urban Roadmaps, taking additional data fromthis Dutch study. We used these combined sets of data to work out an average commute distance of 30.51 km by car and 10.17 km by bus.
Taking 254 as the average wokring days in a year (calculated from the annual working days ina number of different countries), we were able to estimate average CO2 emissions from one year of commuting. This worked out at 1.162431 tonnes for commuting with a (non-electric) car, and 0.17565624 tonnes for commuting via public transport. These numbers, along with information on CO2 emission data on hybrid and electric cars, were used to create the footprint adjustments for transport.
Points | Roughly corresponds to | Footprint adjustment in tonnes |
---|
0 | I walk or cycle mostly, and/or work from home | -1.162431 |
25 | I commute via public transport | -0.5812155 |
50 | I commute via an electric car | 0 |
75 | I commute via a hybrid car | +0.5812155 |
100 | I commute via a petrol/diesel car | +1.162431 |
Adjustment for household energy
Mapping the carbon footprint of EU regionswas the main source of data we used for household energy adjustments, in which it's calculated that the average CO2 emissions for household electricity and fuels in the EU is 1.90892 tonnes per year. We also looked at additional data on US household emissions published in thisCarbon Footprint Factsheetby the University of Michigan.
Points | Roughly corresponds to | CO2 adjustment in tonnes |
---|
0 | Live off-grid on 100% renewable energy | -1.90892 |
25 | Live on-grid with mostly renewable energy | -0.95446 |
50 | My home is powered by a mix of fossil fuels and renewables | 0 |
75 | My home is powered primarily by fossil fuels with some renewables | +0.95446 |
100 | My house is 100% powered by fossil fuels | +1.90892 |
Flights
From an individual's perspective, flying causes carbon emissions on a far greater scale to diet, transport and household energy. Emissions from flights can also be calculated in a more accurate manner. With this in mind, as part of your carbon footprint calculation we ask you directly for the number of short-haul (6 hours or less) and long-haul flights you've taken in the last twelve months. We use an average carbon footprint of 0.2 tonnes per short-haul flight, and 2.863 tonnes per long haul. We calculated these amounts using data from theEuropean Aviation Environmental Report 2019and other sources.
We then do a simple sum up of the emissions from the flights taken, and add the result to your carbon footprint.
Final calculation
With all of the above information, the final calculation of your annual carbon footprint becomes:
- Average per capita CO2 emissions of the country you live in
- Plus or minus the adjustment for diet
- Plus or minus the adjustment for transport
- Plus or minus the adjustment for your household energy sources
- Plus emissions from flights you take, if any
Finally, we divide this annual total by 12 to give you your monthly carbon footprint, which you can then offset on an ongoing basis.