How to calculate the carbon footprint of your business trip

Use the formula and figures below to calculate the carbon footprint of your business trip. You can look up the the carbon emissions for frequent AU business trip routes in the table at the bottom of the page.

Do you have any questions?

You are welcome to email us at greenteam@au.dk or contact AU’s Green Team.

HOW TO CALCULATE THE CO2 EMISSIONS OF YOUR TRIP

Calculate the distance of your trip in km (find out how here).
Multiply the distance by the emissions factor (EF) for your means of transport (which you’ll find in the table below).
If your trip involves multiple means of transport, you’ll need to calculate a result for each of them and add them together.

Means of transport	Emissions factor (EF (grams CO₂ per km)
Diesel train – Denmark	48
Electric train – Denmark	7
Electric train – abroad	10
Electric car – urban driving conditions	24
Electric car – rural driving conditions	24
Electric car – motorway driving conditions	31
Electric car – multiple road types	27
Petrol car – urban driving conditions	193
Petrol car – rural driving conditions	125
Petrol car – motorway driving conditions	134
Petrol car – multiple road types	141
Air travel	109

The calculations in depth

Dive a bit deeper into the formulas and EFs presented here.

Did you know that....

an hour-long online meeting emits up to 1,000 grams of CO₂?
a car trip of 100 km in a petrol car on the motorway emits 13,400 grams of CO₂?

Example 1

If you travel 100 km by electric train in Denmark, this is how you calculate the carbon footprint of your trip: 100 x 7 (EF for electric train in Denmark) = 700 grams CO_2-

Example 2

If you travel with another passenger in an electric car from Aarhus to Aarhus Airport (Tirstrup), a trip involving multiple road types, and then fly to Madrid, this is how you calculate the carbon footprint of your trip:

The distance from Aarhus to the airport is 45 km. The EF for electric cars, multiple road types, is 27. So 45 x 27 = 1,215 grams CO₂. To find your personal carbon footprint, divide the result by two, because there are two passengers in the car: in other words, 608 grams of CO₂per passenger.
The distance as the crow flies from the airport in Tirstrup to Madrid is about 2,045 km. The EF for air travel is 109. So 2,045 x 109 = 222,905 grams of CO₂
Total emissions for car and air travel from Aarhus to Madrid for one passenger is thus 608 + 222.905 = 223.513 grams CO_2.

CO2 EMISSIONS FOR SELECTED DESTINATIONS

Look up the CO₂ emissions generated by travel to selected destinations in this table. Emissions have been calculated for travel by electric train, electric car, petrol/diesel car and air travel.

Route	CO₂emissions: travel by electric train per passenger (gram)	CO₂emissions: travel by electric car per passenger (gram)	CO₂emissions: travel by petrol/diesel car per passenger (gram)	CO₂emissions: air travel per passenger (gram)
Aarhus-Copenhagen	3,060	8,262	43,052	21,696
Aarhus-Oslo	9,010	24,327	126,763	43,884
Aarhus-Stockholm	8,390	22,653	118,040	72,387
Aarhus -Munich	11,280	30,456	158,700	104,387
Billund-Frankfurt	7,750	20,925	109,036	62,115
Billund-Amsterdam	7,360	19,872	103,549	43,735
Billund-Paris	11,980	32,346	168,548	123,158

Number of passengers in the car: Note that the calculations for cars (petrol and electric) assume that only one passenger is travelling in the car. If there are multiple passengers, the figure in the table should be divided by the number of passengers.

Ferry travel is not included: The calculations assume that the car/train drives the entire way from A to B, without being transported by ferry at any point.

The calculations in depth

Background

About the emissions factors
The EFs express CO₂ emissions per km. The EFs were calculated by the Danish Centre for Environment and Energy (DCE), which is also responsible for the national EFs. Danish EFs for diesel and electric trains were supplied by DSB.

Dates of EFs
The EFs for cars are from 2020; the EF for air travel is from 2021. The date of the EFs for trains has not been disclosed. EFs can fluctuate from year to year. For example, they might fall due to new, more fuel-efficient motors in cars and planes. However, based on historical data, it’s estimated that these emissions are gradually increasing.

Cars

EFs for petrol cars
EFs for petrol cars have been calculated using a weighted average of emissions from diesel and petrol cars.

Calculating emissions from cars with multiple passengers
Note that the EF for the trip must be divided by the total number of passengers to calculate at the EF for each passenger.
Example: The CO₂ emissions for a car trip is 1,200 grams. If there are four passengers, the emissions per passenger are 1,200 / 4 = 300 grams CO₂.

Trains

Calculation of distances for the train trips in the table
The estimated distances of the train trips between the destinations in the table are based the distance by car as calculated by Google Maps. This does not correspond to the exact distance by train, as train tracks don’t run parallel to roads. However, this is the most accurate publicly available method of calculation.

Air travel

EFs for air travel
The EFs per km for air travel are based on an average of the EFs for four medium-distance routes frequently travelled by AU staff. The routes are Aarhus-Oslo, Billund-Frankfurt, Billund-Amsterdam and Billund-Paris.

Calculation of distances for the routes in the table
The estimated distances of the air travel routes are based on the geodesic distance (‘as the crow flies’) between the two destinations as calculated by Google Maps. The geodesic distance may differ from the actual distance flown, for a variety of reasons. However, this is the most accurate publicly available method of calculation.

Revised 21.07.2023

Greenteam@au.dk