Sammendrag
A compact timber-framed roof is interesting for several reasons. The construction allows drying out against the indoor air which can increase the construction's climate resilience. In addition, the possibility of insulating between the roof beams provides a reduction in both building height and material use. The focus on material use and greenhouse gas emissions for buildings is increasing. This study has been aimed at a roof structure used in a pilot project for a Zero Emission Building. The interest for such buildings and constructions are increasing. The analysed construction is a sloping timber-framed roof with solar panels and smart vapour barrier. The construction differs from previous studies with an air cavity between the solar panels and roofing membrane, resulting in the roofing membrane not being directly exposed to solar radiation. Temperature conditions in the air cavity is essential for the drying potential of the structure. In a project assignment in the autumn of 2020, the temperature conditions in the air cavity at the pilot project was investigated. By using calculation software, the temperatures found in the project assignment have been recreated. This is to be able perform a moisture technical analysis of the construction with a calculation software for heat and moisture transport. The analysed pilot project in the study is located in Trondheim. Various sensors are installed in the construction measuring moisture content, temperature and relative humidity. In addition to assessing the moisture safety of the pilot project, the measured conditions in the roof structure was recreated using calculation software and measured climate data. The main focus of the thesis is a parameter study to investigate how to increase the robustness and define critical parameters for the performance of an equivalent roof construction as in the pilot project. It is also desirable to elucidate the extent to which the air cavity limits the drying possibilities of the structure. The parameter study carried out with calculation software for heat and moisture transport revealed that the moisture level in the beams and wooden sheathing when closing the structure is of great importance for the risk of mould growth. The parameter study is based on closing the construction in the autumn. This means that the structure does not have the ability to dry in the first period of time, resulting in risk for mould growth until the structure dries from the spring. Larger volumes and more moisture in compact wooden beams result in a greater risk of mould growth compared to I-beams. The range in diffusion resistance for the smart vapor barrier is important, where it is beneficial with a large range in diffusion resistance, thus it is most functional both in summer and winter. Climate variations illustrate that colder climates with less solar radiation reduce the drying potential of the roof, correspondingly higher solar radiation increase the drying potential. At the same time, it appears that climates with mild winters increase the risk of mould growth. As a result of the temperature conditions for mould growth being present for an extended period when the moisture level is high. Throughout the parameter study, the construction shows good drying potential, also for different climates. Calculation program for mould growth considers the risk of mould growth to be acceptable for most calculation variants.