The current building industry needs drastic transformation to meet new performance standards regarding energy use and indoor climate requirements. It so happens that even with new buildings, the results leave something to be desired. This Master thesis describes the specific case of an atrium in the Deltion College building. The research is carried out to find which climate requirements are not met and how they can be improved. The main focus is on visual and thermal comfort. The design is the result of a design-by-research approach in which the maximum result is achieved with minimal interventions. Simulations are used to find the most comfortable solution with the highest energy efficiency. This research shows an example of how a building can be made more sustainable while improving indoor comfort.