Abstract:
To reach European climate neutrality by 2050, the strategic importance of retrofitting the existing building stock is clear. For this scope, thermal rendering systems have emerged as a very feasible solution for historic and traditionally constructed walls. Nonetheless, a definitive guideline for the selection of suitable solutions for the application in this context is not yet available. This research aims at providing recommendations for the choice of hygric-compatible solutions in an early-stage design, for the context of temperate climates with mild winters. In this study, the massive masonry walls of three historic buildings located in Portugal and Italy are considered. Mono-dimensional hygrothermal simulations are validated against the data measured on-site. Simulations are then used to evaluate the impact of thermal renders on the walls, in comparison to more common insulation materials. Two moisture-related risks are considered: moisture accumulation and reduction of drying. This investigation shows that, for traditional porous walls, retrofitted configurations should be simulated not only under typical operational conditions but also considering a very high initial water content in the wall substrate, when the insulation is applied. Otherwise, moisture-related risks may be overlooked. Recommendations on the choice of thermal rendering systems are provided.
