This section contains general information on how we have calculated the emissions from travel by train, car, bus, flight and ferry. The full scientific underpinnings for these calculations can be found in our Methodology Report.

TRAIN

The calculation of the climate footprint of trains is an average for trips by electric train. Emissions from individual trips vary according to the energy consumption of the specific train and its occupancy rate. There is also a difference between an electric train operated in the Nordic countries or in Europe. This is because emissions from electricity production differ from country to country. In our calculations, we do not take into account the fact that some rail companies use eco-labelled electricity. Read more about why in the Methodology Report.

We have estimated that train travel in the Nordic countries (except Denmark) causes 7 grams of CO2 per passenger kilometre (Electric train Nordic countries) and that an electric train in Europe and Denmark (Electric train Europe) causes 24 grams. For diesel trains, emissions are estimated to be 91 grams of CO2 per passenger kilometre, regardless of the country. 

Some trains in Europe run on diesel, but we have nevertheless chosen to have “Electric trains Europe” as the default outside the Nordic countries. This is partly because the level of electrification in Europe is relatively high (80%) and the level is also rising. Non-electrified tracks are mostly used for local trains and infrastructure maintenance.

If you know that a leg of your trip is operated by diesel train, you can change the type of train in the calculator to “Train Diesel” for a more accurate calculation.

CAR

In the calculator, you can choose between 4 different sizes of the car and 9 different fuels. We have taken the most common combination in Sweden as the default choice, which is a medium-sized diesel car. According to our calculations it is causing emissions of 137 grams of CO2 per vehicle kilometre, which is based on data in a report from the Swedish Energy Agency. The quantity of emissions per person will depend on how many people travel together in the car, which you enter yourself when using the calculator. The basis for calculating emissions per vehicle kilometre for different fuel and vehicle types follows below:

Grams CO₂ emissions per vehicle per kilometre

	Petrol	Diesel	Biodiesel/HVO d)	Electric (Nordic)a)	Electric (Europe) a)	Natural gasb)	Biogas d)	Blend natural/ biogasc)	Ethanol E85 d)
Small car	127	104	28	11	34	137	19	20	56
Car	167	137	37	14	45	181	26	27	74
Big car/7 seater	220	181	49	18	60	238	34	36	98
Camper	327	267	72	27	88	353	50	53	145

^a) For the calculation of emissions from electricity use, see Section 2.2.

^b) The main fuel used abroad is natural gas (Source: miljöfordon.se)

^c) Blend of biogas 95% and natural gas 5%, average for sold gas for cars in Sweden 2021. (Source: Energigas Sverige)

^d) For the calculation of emissions from biofuels, see Section 2.3.

The starting point for the calculations was the energy consumption of the average car (just ‘Car’ in the calculator). For big cars, we have added 34% and for small cars reduced the figure by 24%. The figures include emissions from the extraction, production and distribution of the fuels, but not emissions from the production of vehicles and their infrastructure.

BUS

The emissions per passenger kilometer for bus legs of a trip depend mainly on the occupancy rate of the bus and the fuel used. The default in the emissions calculator is the diesel which is stipulated by Swedish law and where the emissions are 28% lower that fossil diesel due to blend-in of biodiesel.  The calculation is also based on an assumption of the average of 28 passengers per bus and a fuel consumption of 2.6 litres per 10 kms (Swedish Bus and Coach Federation, 2022). The result is emissions of 25 grams of CO2 per passenger kilometer.

If you know that you will be travelling on a bus or coach running on 100% biodiesel (HVO100), you can choose this in the calculator. The emission factor for this is estimated at 7 grams of CO2 per passenger kilometer.

AIR

The default option for flights in the calculator is a scheduled economy class flight and we estimate that this results in emissions of 133 grams of CO2 equivalents per passenger kilometer. Emissions from flights are also affected by the seat class chosen. Premium Economy, and Business class in particular, take up more space and limit the possibility of carrying more passengers who share the emissions.

On average, charter flights have a higher occupancy rate than scheduled flights, which also affects the calculation of emissions per passenger kilometer, and we therefore calculate emissions from charter flights at 118 grams of CO2 equivalents per passenger kilometer. In view of these differences, in the calculator we have made it possible to choose between a scheduled flight and charter flight and to choose the seat class.

The 133 grams of CO2 equivalents per passenger kilometer include the non-CO2 effects, which we have obtained by multiplying the carbon dioxide emissions by a factor of 1.7. This is in line with the most well-established scientific estimate; however, there is considerable uncertainty about the magnitude of non-CO2 effects. The emissions calculation also includes upstream emissions, meaning those arising in connection with the extraction, production and distribution of aviation fuel.

Shorter flights result in high CO2 emissions per passenger kilometer because the ascent consumes a lot of fuel. In addition, shorter flights do not normally contribute to non-CO2 effects as they do not fly at very high altitudes. The opposite is true for long flights: the ascent is only a small part of the whole flight, but on the other hand, the flight is largely at a high altitude, which adds an extra climate footprint. Due to this it is reasonable to assume roughly the same emissions per passenger kilometer for short and longer flights. See more detailed reasoning in the Methodology Report.

FERRY

As with the other modes of transport, emissions per passenger kilometre may vary depending on many factors. One important factor is the speed of the ferry. High-speed ferries, used for some trips to Gotland, use twice as much energy per passenger kilometre as regular ferries (e.g., those used from Sweden to Finland and Denmark), resulting in higher emissions than air travel. 

In addition, how emissions are distributed between the passengers and freight being transported on the ferry plays a major role. Unfortunately, different ferry companies have chosen to use different principles for doing this, making it difficult to compare them. Some use the area method (area utilised for passengers and for freight, respectively) while others use the weight method (weight of passengers and weight of freight). In the calculator, we used financial allocation. Here, emissions are divided between passengers and freight based on their share of the ferry company’s income from passengers and freight. The logic behind this is that it is the revenue of the ferry companies that drives their ongoing operations, and that it is therefore reasonable that the proportions from their revenue are used as the basis for allocating the emissions. For example, if 70% of their revenue comes from passengers and 30% from freight, then 70% of the emissions are allocated to passengers and 30% to freight.

The average emission factor used in the calculator for travel by ferry is 226 grams of CO2 per passenger kilometre. This figure is for regular ferries, not high-speed ferries.

 

SUMMARY OF EMISSION FACTORS FOR DIFFERENT MODES OF TRANSPORT.
Car emissions are divided by 3, which is the average number of persons for trips of over 30 km*

Transport mode	gCO2e/pkm*	grams CO2/km/vehicle
Electric car (Nordic countries)	5	14
Electric car (Europe)	15	45
Petrol small car	42	127
Diesel car	46	137
Diesel big car	60	181
Camper/caravan diesel	89	268
Scheduled flight (Economy)	133	-
Charter (Economy)	118	-
Scheduled flight (Business)	298
Electric train (Nordic countries)	7	-
Electric train (Europe)	24	-
Diesel train	91	-
Bus, standard diesel	25	-
Bus biodiesel 100%	7
Ferry	226	-

* Own calculations based on the Swedish National Travel Survey 2011-2016 (RVU 1116 Sweden) (Trafikanalys, 2017).