This degree project aims to serve as a basis for the reconstruction of Västerås old steam power plant, called the Kokpunkten project, which is a listed building. The work is based on an extensive literature review on the building physics phenomena and concept as well as a study on how a building’s listing affects the possibility to take any measures. Moisture calculations were performed on four different cases with additional insulation. The risks of microbial growth in the respective case were then evaluated. The calculation results show that the best course of action is to add insulation outside. With regard to the building’s listing status, it is concluded that adding interior insulation in combination with façade impregnation is the most suited alternative.