The article describes a student research project concerning Indoor Climate and Fire Precautions in five Finnish Churches. This was a joint international project between Gotland University and Novia University of Applied Sciences. The goal was to learn how indoor climate and fire precautions can be designed in a fashion that supports the preservation of wooden constructions and artifacts. The purpose of this paper is to arouse awareness of the impact indoor climate has on historic buildings, furniture and fragile objects made of wood. At the same time we want to spread the knowledge to conservators, engineers, architects, builders and above all, to designers of heating systems.