When Movetia approved the funding for our exchange, the environmental project to compensate for the CO₂ emissions was already a central part of the programme. In its evaluation, Movetia explicitly highlighted that the project had exemplary value because it included the modelling of approaches to compensate for the CO₂ emissions caused by the flight, and could serve as a model for future mobility projects.
This made one thing clear: the question of flight emissions was not a minor addition to the exchange, but an important factor for the success and credibility of the whole project.
In this context, our environmental work did not begin only with the later compensation measures. It began with the choice of the flight tickets themselves. From an emissions perspective, a direct flight with Swiss would have been an obvious option, since direct flights generally produce fewer emissions than flights with stopovers. However, because of the very high price, this option was not possible. We therefore had to look for alternatives that were affordable for a student group while still being as environmentally responsible as possible.
It quickly became clear that this decision was much more complicated than it first appeared.
Our goal was to find a flight that was both financially realistic and environmentally reasonable. At first, we selected Turkish Airlines. The travel agency estimated the emissions for this flight at 3124 kg CO₂ per passenger. This was slightly above average, but still seemed acceptable.
However, other sources gave very different figures. Depending on the online calculator used, the result changed significantly. This made it difficult to make a well-informed decision.
We eventually received valuable support from Filipa Fernandes, Environmental Sustainability Specialist, and Imane Trafi from Pro Sky. Pro Sky specializes in group flights and helps find suitable flight solutions for group travel.
Filipa Fernandes and Imane Trafi helped us better understand the different figures and identify more reliable sources for calculating emissions. We are therefore especially grateful to Filipa Fernandes and Imane Trafi from Pro Sky, who invested a great deal of time and commitment in this project. On the Pro Sky team page, Filipa Fernandes is listed as Environmental Sustainability Specialist.
One particularly useful tool was the emissions calculator by atmosfair.
This made one point very clear: to obtain reliable values, it is not enough to enter only the route or a general aircraft category. The exact aircraft type is crucial.
For example, Cathay Pacific uses an Airbus A350-900 between Zurich and Hong Kong and a Boeing 777-300ERbetween Hong Kong and Tokyo. When these exact aircraft types are entered, the calculated climate impact is about 2543 kg CO₂ per passenger. This is around 12% below average.
By contrast, if only generic aircraft categories such as “Airbus A350” and “Boeing 777” are used, as many online calculators do, the calculated value rises to 3232 kg CO₂. That is about 30% higher. The difference is therefore substantial.
Conversely, the more precise calculation also showed that the Turkish Airlines flight we had originally selected performed much worse than first assumed. With the correct aircraft types, the emissions amounted to 4006 kg CO₂ per passenger, around 40% above average.
By the time it became clear that Cathay Pacific would have been one of the lower-emission options, the relevant tickets were unfortunately already sold out. In the end, we chose a flight with KLM. The emissions were estimated at about 3042 kg CO₂ per passenger, around 5% above average. This solution was not perfect, but it was a reasonable compromise between price, availability, group organisation and environmental impact.
It was also interesting to learn that the calculation tool used by atmosfair was partly developed at ETH Zurich.
For us in Wettingen, this was particularly remarkable. With online tools like this, one often thinks of international platforms and distant institutions. It was therefore a pleasant surprise to discover that part of the scientific basis for this tool was developed practically in our neighbourhood.
Another important lesson was that lower emissions do not automatically mean better technology. They are often also related to how many passengers are transported on a plane. More passengers per flight means lower emissions per person — but often also less legroom.
In addition, European airlines are legally required to use a certain proportion of sustainable aviation fuels. This can also influence the emissions balance. Atmosfair also offers the possibility of directly offsetting flights. For our KLM flight, with around 3042 kg CO₂ per passenger, the compensation would cost about CHF 85. Similar offers are available from many airlines. At the same time, there is ongoing debate about whether such amounts are sufficient to fully compensate for the actual climate impact of flying.
The search for the lowest-emission flight ticket possible was therefore more than an organisational task. It became the first concrete step of our environmental project. It showed us how difficult it can be to find reliable information, compare figures correctly and make responsible decisions.
The environmental project has now been completed: the trees have been planted, and the emissions of our exchange will be compensated over the next 20 to 30 years. Buying the flight tickets was the beginning of this process — and at the same time an important lesson: sustainability often requires careful research, critical thinking and many practical compromises.