A multistep approach for the hygrothermal assessment of a hybrid timber and aluminium based facade system exposed to different sub-climates in Norway

Abstract

This paper describes a multistep approach that allows the design and assessment a hybrid, timber-based, facade system that can withstand current real conditions without being prone to mould. This approach is aligned with today’s drive for a more sustainable built environment. A typical office building with the hybrid system was simulated in a BES tool to obtain the indoor conditions in three selected locations in Norway. Historic measured weather data were used to build climate files, in accordance with ISO 15927-4 methodology. The global radiation was split using the DIRINT model, while a user-independent code was developed to find and fill the weather datasets gaps. A model was built using a one-dimensional HAM software for each facade section to assess its hygrothermal performance, whose studies are scarce in literature, and determine whether the system is appropriate for Nordic climate. This analysis included mould growth risk assessment, determining the variance of the transient U-values and the influence of the wood surface treatment on the drying capacity of the facade. The obtained energy consumptions are in accordance with the current Norwegian regulations. Under normal conditions, the system works properly. However, problems arise if a higher initial moisture content exists in the materials.