Influence of Variable Moisture Conditions on the Value of the Thermal Conductivity of Selected Insulation Materials Used in Passive Buildings

Abstract

The interest in passive construction that has low demand for thermal energy continues to grow every year. It is related to both the reduction in maintenance costs of buildings and the growing environmental awareness in societies. Passive houses are characterised by very good thermal insulation properties of their external partitions. This paper presents the results of tests on the thermal conductivity for three different types of building materials, assuming their use as thermal insulation. The materials were subjected to water absorption tests during long-term immersion. The purpose of this study was to simulate water absorption caused by long-term water exposure. The tests were carried out on a perlite concrete block, a sheet of polyurethane foam applied by spraying and expanded clay in a loose form in three different fractions. The tested insulation materials were selected due to their different form, structure, and porosity characteristics, which largely determined the value of the thermal conductivity. A perlite concrete block is a new, innovative product, of which manufacturer’s data are not yet available as the product is currently at the stage of detailed research. The results were analysed statistically and used in graphs to show the dependence of the value of the thermal conductivity on moisture content of the samples. The purpose of this study was to indicate the importance of the proper incorporation of insulation materials into buildings, their storage before construction and use in the post-construction phase. Building standards for passive houses place high demands on materials used. In order to fully enjoy the advantages of passive buildings, i.e., lower energy consumption and benefits for the natural environment due to lower consumption of energy generated from non-renewable energy sources, it is necessary to use certified building materials and ensure proper use of objects. The studies quoted in this paper indicate to what extent the influence of moisture content negatively affects the properties of insulation materials in external partitions.

Changes in Subgrade Insulation Conductivity With Varying Moisture Content

“…Table 3 Material characteristic properties (Jerman & Cerný, 2012) Table 2 Experimental vs. literature thermal conductivity. Column [20] is ISO 2017 and column [58] is from a Polish paper written in 1991 (Szymczak-Graczyk et al, 2022).…”

Changes in Subgrade Insulation Conductivity With Varying Moisture Content

“…Due to its buoyancy, the polyurethane was only partially submerged, so it never reached 100% moisture content. During the draining process, the thermal conductivity was measured twice, and during the drying process, it was measured once per week (Szymczak-Graczyk et al, 2022). From this testing, Figure 3 was created.…”

Fire safety study of a perlite concrete chimney and wooden ceilings used in buildings based on experimental tests and CFD analysis

“…Lightweight concretes, forming the casing of chimneys, are characterised by good insulation. 28 The high insulation performance is obtained because the concrete includes volcanic aggregates such as LECA, scoria, and perlite. 27,29,30 Paper 23 describes a study of an innovative chimney with a ceramic liner in a perlite concrete casing.…”