Nowadays, most humans spend approximately 90% of their time indoors, mostly related to work activities. Parallel to this is the development of energy-efficient buildings in the real estate sector, which require automated ventilation systems. As a result, indoor environmental quality has become an important player in shaping human health and behavior. One particular factor is the concentration of indoor carbon dioxide (CO₂). There is increasing evidence that the level of indoor CO₂ can harm the cognitive performance and long-term health of occupants. While in the past, CO₂ has been used as a proxy for other harmful substances in the air, more research indicates that CO₂ itself could directly cause cognition impairments and adverse physiological responses. However, the underlying physiological mechanisms in the brain are still unclear. Moreover, the cognitive impairment due to CO₂ exposure might lead to changes in individual behavior, in particular regarding individuals’ risk-taking and level of patience which are key determinants in economic decision-making.

Current evidence is still inconclusive at which concentration levels CO₂ starts to impose these effects. There is also limited knowledge about the effect of moderately high CO₂ levels over several hours. Additionally, to the best of our knowledge, there is currently no study that investigates the effect of moderately high indoor CO₂ concentration on human energy metabolism, which is a crucial factor in determining the risk for individuals to develop metabolic diseases.

This interdisciplinary study aims to contribute new insights to different streams of literature by examining the isolated effect of medium exposure (over several hours) to CO₂ on both, cognitive and behavioral responses a well as physiological parameters. This contributes to closing several research gaps. Firstly, the study will investigate whether exposure of several hours to a typically occurring indoor CO₂ concentration of 0.3% affects cognition, economic decision-making, and health. Secondly, the close monitoring of subjects’ physiological conditions will allow insights into possible underlying mechanisms causing such cognitive impairments. Thirdly, we will investigate the effect of several hours of exposure to elevated levels of CO₂ that are representative of conditions in offices. Understanding under what conditions, cognitive capacities, decision-making, and health of occupants can be optimized is key for future productivity growth and sustainable employment.