Abstract
Interior insulation is a crucial retrofit measure to improve the energy performance of historical building while preserving their exterior appearance. However, it affects the hygrothermal behaviour of the wall and for this reason it must be planned with a very detailed and careful approach. This becomes even more important when dealing with buildings that are subject to extreme climate conditions such as mountain huts. They are typically exposed to very cold temperatures for all year and to an elevated driving rain load.This paper presents the methodology followed to design the interior insulation intervention of a mountain hut located in Trentino-Alto Adige (Italy). The methodology is centred around the use of hygrothermal dynamical simulations at component level,but several other tools are used to identify the right input for these simulations: the analysis of monitoring data of nearby weather stations to define the exterior climate, simulations at the building level to calculate the interior climate and laboratory measurements to identify the correct material properties.