Renovation of residential buildings: strengths and weaknesses of a research approach based on prefabrication and real case-studies
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Vapor barriers and retarders are often needed to improve the hygro-thermal performance of the building envelope. Their use is particularly important in prefabricate timber façade, especially when critical boundary conditions occur. In literature, very little is known on the actual performances of complete envelope packages integrating these membranes, since most of the previous studies focused on the analysis of single components. However, considering the growing interest and use of these timber facade elements, an analysis of the performances of integrated membranes is needed for a correct design of the whole wall structure. Thus, the novelty of this work lies in the validated analysis of a building envelope sample integrating membranes with a variable vapor diffusivity. The study aimed at investigating the behavior of an envelope component integrating a hygro-variable membrane and a breathable membrane by using computer simulation and experimental facilities. A thermo-hygrometric analysis of the element has been performed in Delphin, and an experimental activity has been set up, aiming to validate the numerical model, measuring temperature and relative humidity at different layers. Two sets of boundary conditions have been accurately chosen to be critical for the building component in terms of thermal and humidity transmission. Results show a very good agreement for one test condition. For the second one, the measurement uncertainty has increased. Possible reason is the presence of condensate in the measurement box frame caused by the first test run. The experimental set-up developed is a relatively easy-to-replicate layout for the validation of similar complex packages. Compared to previous studies, the experimental set-up used in this research is indeed simpler and less expensive.