Hygrothermal simulation assessment of internal insulation systems for retrofitting a historic Danish building

Abstract

The built environment is accountable for 1/3 of the European energy consumption. Thermal insulation is a key factor affecting the energy performance of buildings. Historic buildings typically were made with solid external walls of brick masonry or natural stone, rarely insulated afterwards. Often the buildings have worth-preserving façades making internal insulation the only feasible technique, however significantly modifying the hygrothermal performance of the façade. The research objective of this paper is to simulate the hygrothermal performance of solid masonry walls in an old Danish hospital that will be internally insulated following the Danish requirement (U-value) for external walls (change of use of buildings) and transformed into dwellings, involving different insulation systems. Heat loss and masonry moisture content level after adding internal insulation and the possible effects of hydrophobization on the moisture content is simulated. Simulations show an increased moisture content in the original wall when adding internal insulation implying an increased risk for moisture-related damage (mould growth, frost damage and interstitial condensation). The results also show that hydrophobic impregnation of the internally insulated facades may be vital in avoiding moisture problems and securing a moisture-safe energy renovation of buildings like the one studied.

An overview of hydrophobic treatments and their application with Internal Wall Insulation

“…It has been proposed that a partially effective HPT may provide a useful balance of positive and negative impacts (Metavitsiadis et al, 2017). Several simulation studies explore the hygrothermal performance of one, or a small number of masonry materials, IWI and treatment combinations (Arregi and Little, 2012;Finken et al, 2016;Soulios et al, 2019) 3.4 Laboratory work HPT have also often been studied in the laboratory. Several techniques such as X-Ray Diffraction, Fourier Transform -Infra Red and Gas Chromatography can be used to infer the composition of products (Witte et al, 1996).…”

“…HPT may help reduce moisture risks in masonry walls by reducing the amount of rain absorbed; they have been deployed on walls with Cavity Wall Insulation (CWI) (UCL and BRE, 2021a) , Internal Wall Insulation (IWI) (de Place Hansen et al, 2021;Martel et al, 2021;Soulios et al, 2019;Vereecken et al, 2020), as well as in the absence of insulation to e.g. arrest/impede weathering in stone monuments and to prevent graffiti.…”