Evaluating the hygrothermal performance of prefabricated timber frame facade elements used in building renovation

Refurbishing existing buildings plays a key role in reducing the overall energy consumption of the building stock. The use of prefabricated timber facade elements in the renovation of buildings is often beneficial due to their limited thickness and weight, the integration of HVAC and windows, the functionality and speed during works etc. Despite these proven benefits, these systems are not commonly used in Belgium. The research project of which this work is part of, therefore aims to stimulate the use of these elements for renovation by eliminating technical barriers that may hinder their use. In this paper, the impact of different design choices on the hygrothermal performance of elements that are installed in front of an existing facade, e.g. a cavity wall, is evaluated. The protection of the existing inner cavity leaf after demolition of the outer cavity leaf, the integration of a vapor retarder between the new element and the existing construction and the use of cellulose insulation proved to be advantageous measures to reduce the risk of degradation. (C) 2017 The Authors. Published by Elsevier Ltd.