CO2-Data influence food choices: researchers publish data from a field experiment in one of the largest canteens of the Munich Student Union

To eat more sustainably – a New Year’s resolution for many people who started the new year with the Veganuary. But changing your own consumer behavior is not always easy. CO2 labels could help. In a field experiment, researchers from the TRR 266 Accounting for Transparency from HU Berlin, LMU Munich and Aalto University (Finland) found that CO2 labeling of food encourages people to eat more sustainably. What matters is how the information is presented. The effect was greatest when CO2 data were visualized in traffic light colors or presented as environmental costs.

Sustainable food consumption is not only a New Year’s resolution that is currently trending, but also part of the political agenda of the Federal Government. In December, Federal Minister of Agriculture Cem Özdemir spoke out in favor of healthier and more sustainable food in canteens or refectories. This would be a first step towards more sustainable food consumption. After all, six million people in Germany eat out at lunchtime – in canteens, refectories or similar establishments. The new nutrition strategy is going to be decided by the end of 2023.

But what does it take for consumers to actually change their eating habits? This is where the TRR 266 study comes in. The findings of the field study can help to develop CO2 labels that encourage consumers to consume more sustainably: “In our study, we show that providing emission data reduces the demand for CO2-intensive dishes such as meat and fish and thus the overall CO2 footprint of the chosen food is reduced,” explains Prof. Dr. Joachim Gassen, Professor of Accounting and Auditing at the Humboldt University in Berlin. “This effect is particularly strong when the CO2 information is visualized in traffic light colors or presented as environmental costs in euros per 100 g,” Gassen continues.

The 10-day field experiment was carried out in one of the largest canteens of the Munich Student Union, the Mensa Leopoldstrasse. During the test period 8,000 canteen visitors took part in the experiment. The menu displays provided more than the usual information, such as the prices of the dishes or their main ingredients and also how high the CO2 footprint of the respective dish is. The presentation of the CO2 information was changed once a day during the experiment to test which form of visualization had the greatest impact on consumer behavior.

Some visitors were informed about the environmental costs in euros that their lunch causes. By reading the display information others learned how much of their daily CO2 budget is consumed by the dish they have chosen. Still others were informed about the CO2 emissions in grams caused by the dish. The information was also supplemented by coding in traffic light colors (green, yellow, red). Ultimately, it had the greatest effect when the visitors found out how many euros in environmental damage their lunch caused. In this way, up to almost ten percent less CO2 was caused by the meals than without the information on CO2 emissions.

For the TRR 266 research team, the study shows concrete starting points for politics and companies to support more sustainable behavior: “Our experiment shows that information on the CO2 footprint can lead to a change in consumer behavior. This insight can help politics and business to take appropriate measures for a more sustainable future,” explains Prof. Dr. Thorsten Sellhorn, Professor of Accounting and Auditing at the LMU Munich. “Companies could, for example, voluntarily choose to disclose CO2 claims for food or other products and services.”

The experiment was an important mission not only for the research team but for those responsible for the canteen, too: “Sustainability and environmental awareness are important values for us, which we attach great importance to when operating our canteens. That’s why we were very happy to support this project,” says Ralf Daumann, head of the university gastronomy department at the Munich Student Union.


Further information on the study as well as video and photo material can be found on our website:

Dr. Ann-Kristin Großkopf and Prof. Dr. Thorsten Sellhorn from LMU Munich, Dr. Rico Chaskel, Simone Euler and Prof. Joachim Gassen from the HU Berlin and Dr. Bianca Beyer, Assistant Professor from Aalto University in Finland were participating on the project. 


Participating Institutions

TRR 266‘s main locations are Paderborn University (Coordinating University), HU Berlin, and University of Mannheim. All three locations have been centers for accounting and tax research for many years. They are joined by researchers from LMU Munich, Frankfurt School of Finance and Management, Goethe University Frankfurt, University of Cologne and Leibniz University Hannover who share the same research agenda.

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