Purpose – The purpose of the paper is to demonstrate that it is completely rational to invest in climate installations for offices designed on the highest comfort category. Design/methodology/approach – By means of a study on a building model it is proved that the benefits of a higher comfort category outweigh the costs of the additional investment, with marginally higher energy costs for cooling. Findings – Depending on the type of climate installation and the comfort class, the additional investment costs can be recovered within six month to two years, due to a higher level of comfort and raised productivity. Originality/value – The relationship between the thermal environment and productivity makes it possible to design on the basis of productivity improvement, resulting in a comfortable working environment and a consistent financial advantage for the organisation. If the indoor environment is henceforth assessed in the context of comfort and productivity, the participants in the housing process who are generally less interested in the aspects mentioned above will eventually incorporate investments in the quality of the workplace in their objects (in connection with the ability to sell and lease real-estate).@en