Numerical Evaluation of the Hygrothermal Performance of a Capillary Active Internal Wall Insulation System under Different Internal Conditions.

Dobrosława Kaczorek

doi:10.3390/ma15051862

Abstract

In certain situations, internal insulation is the only possible renovation option. However, it is risky where there is high humidity in a building and ventilation is not working sufficiently. The internal insulation retrofit changes the original thermal and moisture balance of a wall, therefore, it is necessary to carefully design it already at the initial stage. This paper analyses four interior insulation systems based on open diffusion capillary active materials: wood fibreboards (flex and rigid), perlite boards, and microporous calcium silicate. The hygrothermal performance under the climatic conditions of Central Europe (Poland) was assessed using the WUFI Plus software, taking into account the dynamic variation of indoor and outdoor conditions. The analysis included three insulation thicknesses with different ventilation rates and varying moisture loads. The results show that the hygrothermal properties of the wall change with the increase of insulation thickness and depend on the individual moisture properties of the material. In addition, both the reduction of moisture load and more intensive air exchange improve the hygrothermal properties at the interface between the insulation and the wall. Of all the solutions analysed, the system with perlite board and the system with wood fibreboard showed the worst hygric properties. Conversely, the highest risk of mould and interstitial condensation was recorded for the flex wood fibreboard solution.

Highlights

Academic Editor: As the construction sector is responsible for approx. 40% of Europe’s greenhouse gas emissions [1], the European Commission has begun to take an interest in the industry’s activities
This paper presents a study of an exterior wall insulated from the inside using four different capillary active open diffusion interior insulation systems
The profiles of the total moisture content for all analysed walls show the cyclic seasonality of moisture content caused by seasonal shifts in climatic conditions

Summary

Introduction

Academic Editor: As the construction sector is responsible for approx. 40% of Europe’s greenhouse gas emissions [1], the European Commission has begun to take an interest in the industry’s activities. Not all buildings are suitable for insulation being fitted on the outside of walls In such a case, internal insulation may be the only feasible solution [3], it is often considered more risky due to the presence of thermal bridges [4–6] and the increased likelihood of interstitial condensation [7–10]. Internal insulation may be the only feasible solution [3], it is often considered more risky due to the presence of thermal bridges [4–6] and the increased likelihood of interstitial condensation [7–10] This type of solution increases the diffusion resistance between the existing wall and the occupied zone, which reduces the potential for the wall to dry inwards [9,11]. In order to solve the issues concerning moisture accumulation inside the wall, and to improve its thermal properties, new solutions are constantly searched for. Despite the fact that the ceramic additive works well in other solutions [16], it does not improve the thermal properties of this

Methods

Results

Conclusion