Due to the heritage value of historical buildings, external facades can often not be modified. Therefore, in heritage buildings interior insulation is often considered 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 as parameters such as temperature and precipitation will change over time. Hygrothermal models can provide relevant insights into the risk of deterioration associated with these damage phenomena. However, these 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 explains how these results can be translated into practice, providing building practitioners the most suitable insights and recommendations. The development of an interactive web tool to assess hygrothermal risks is demonstrated and its use and benefits are further elaborated.

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.

Salt-induced deterioration is of significant concern when assessing the degradation risk of masonry facades. Despite extensive knowledge about salt behaviour mechanics, risk assessment of the occurrence of potential damaging cycling remains challenging. Previous studies mainly evaluate single salts, though masonry walls typically contain a mixture of different salt types. Salt damage arises as a consequence of repeated crystallisation-dissolution cycles, which exert pressure on the pore surface of porous building materials. Relative humidity is a major driving factor for the frequency and intensity of these cycles. An extensive study analysed over 11,000 drill samples collected across Belgium identified four typical salt mixtures in heritage structures, categorised as five- and six-ion systems: two with an excess of sulphate (T1v and T1vi) and two with an excess of calcium (T2v and T2vi), with respect to gypsum crystallisation. This paper combines the research on the thermodynamic behaviour and kinetic variables of these salt mixtures with hygrothermal simulations. For the first time, the dynamic risk assessment is conducted using range-based indicators and salt mixtures, rather than single salts with a single threshold criterion offering more realistic insights into the interaction between climate change, interior insulation, salt damage and the hygrothermal properties of masonry constructions.