Influence of Moisture Dry-out on Hygrothermal Performance of Prefabricated Modular Renovation Elements

Renovation with prefabricated modular panels is one way to achieve high energy efficiency and quality both in production and installation processes. The 5-storey building, which is being fully renovated in Tallinn, Estonia, will be insulated with prefabricated modular renovation elements. The hygrothermal performance of the envelope was evaluated with calibrated dynamic hygrothermal simulations and with a mould index model, where calculation results were in good agreement with measured data and are therefore reliable for further research. The calculations were made to evaluate the hygrothermal risks in the building envelope and after the prefabricated modular elements were installed. The focus was on studying concrete wall's dry-out capability and the use of vapor barrier. The initial moisture content of the concrete wall and a right choice of air&vapor barrier layer has considerable impact on the entire envelope performance. As a result of this study, we claim that the risk of mould growth in this structure can be minimized, when the initial moisture content (IMC) of the existing concrete large panel element is w≤55 kg/m3 and PE-foil as air&vapor barrier is used or when IMC is w≤75 kg/m3 and the oriented strand board (OSB) as vapor control layer or when IMC is w≤110 kg/m3 and smart vapor retarder (0.2 m