Improving hygrothermal risk assessment tools for brick walls in a changing climate

Abstract

Due to the heritage value of historical buildings, the external facade can often not be modified. Therefore, heritage buildings require interior insulation when undergoing an energy renovation. However, interior retrofitting drastically changes the hygrothermal behaviour of a wall and can potentially cause moisture-related problems. Besides an interior retrofit, a changing climate might also trigger some of these damage mechanisms since parameters such as temperature and precipitation will change over time. It is proven that hygrothermal models can provide relevant insights into the risk of deterioration associated with these damage phenomena. Heat, Air and Moisture (HAM) tools are commercially available but rarely used in the building industry to study deterioration risks. Translating research into practical tools and guidelines is a challenge across the whole field of building renovation. This paper aims to tackle that challenge, by means of creating a hygrothermal risk assessment tool based on 48,384 HAM-simulations for the climate of Brussels, Belgium. Seven different performance criteria are addressed and discussed: freeze-thaw damage, mould growth, wood rot, corrosion, moisture accumulation, salt efflorescence and bio-colonisation. Subsequent to a sensitivity analysis, the study further investigates how these results can be translated into practice, providing building practitioners the most suitable insights and recommendations.