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• Wind-driven rain (WDR) quantification experimentally on 2 case buildings. • Effect of WDR on hygrothermal conditions in internally insulated masonry studied. • Numerical simulations to determine WDR effect on hygrothermal performance. • WDR models were found to overestimate WDR deposition. • Direct influence of WDR events on RH behind insulation was not detected. An inevitable measure when energy retrofitting historic buildings in Europe, is the reduction of building envelope heat loss. On preservation-worthy facades where external insulation is not an option, installation of internal insulation is gaining pace. The historic buildings in Denmark are often constructed with solid masonry facades and wooden decks. The internal insulation may, however, entail potential hygrothermal risks in walls and embedded wood. Measures such as vapour barriers and capillary active insulation materials are continuously evolving and the subject of much current research. The hygrothermal conditions are of great importance for the durability of the building constructions, and for the health and wellbeing of occupants. Wind-driven rain (WDR) is a central factor contributing to water penetration and moisture loads of the exterior walls. Numerous studies have shown that WDR loads influence the moisture conditions in masonry walls and embedded wooden beams, and can even affect interior relative humidity. In the present paper WDR loads on existing façades in a cold temperate climate were determined by measurements and compared to a semi-empirical model. Simultaneously, the hygrothermal conditions within internally insulated walls with exposed brick and embedded wooden beams were monitored. Furthermore, numerical simulations were implemented for clarification of WDR impact. Hygrothermal simulations and previous studies, inevitably show that high WDR loads result in higher moisture content behind the interior insulation. Results from the field measurements of WDR however, cannot directly be referred to the moisture content measured in walls behind interior insulation or beam ends. However, fluctuations in external air humidity proved to be influential on condiditons in the construction. Implementation of a semi-empirical model for calculations of WDR agreed with previous studies in predictions being too conservative when compared to measured WDR. [ABSTRACT FROM AUTHOR]

In heritage buildings with solid masonry walls, where external insulation is not an option, insulating internally is an alternative way to improve indoor climate and reduce energy consumption and heat loss through external walls. This study presents results from hygrothermal measurements performed in four different buildings in Denmark where internal insulation has been installed. The buildings are all heritage buildings from 1877–1932 and of solid masonry walls. The insulated façades differ in orientation, surface treatments, location, and insulation system. The insulation materials used are phenolic foam and polyurethane (PUR) foam, with calcium silicate channels in a grid of 40 × 40 mm. Measurement results and hygrothermal assessments indicate that a vapour barrier does not contribute positively to the performance of the system and the more vapour open, the better performance on solid masonry. However, the performance is highly dependent on other parameters like insulation thickness and surface treatment, and above all: the external hygrothermal loads. Therefore, before the application of internal insulation, every case should be carefully assessed in order to find the most suitable solution with regards to both thermal and hygrothermal performance. [ABSTRACT FROM AUTHOR]