Hygrothermal analysis of technical solutions for insulating the opaque building envelope

Abstract

The application of insulating materials for energy refurbishment of buildings improves the thermal transmittance of the envelope. However, if not properly planned and realized, it could reduce the wall's drying potential, modifying its original features and leaving it generally more humid. This can lead to moisture damages, humid insulation material and risk of mould growth. To avoid any problem related to the increased presence of water in the building envelope, it becomes therefore essential to perform the so-called hygrothermal assessments. In this regard, the international standards offer, beside the traditional Glaser method based on the mere vapour transport, the use of dynamic hygrothermal simulations. These allow to simultaneously consider the transport and storage of heat and moisture in building materials, the influence of climate (including rain and solar radiation in different locations), user behaviour and initial conditions. The aim of this paper is to compare Glaser and dynamic methods and to highlight their advantages and disadvantages, considering the different approaches to the evaluation not only of superficial and interstitial condensation, but also of durability, considering biological attack, freeze/thaw cycles, corrosion, etc

Exploring Historical Perspectives in Building Hygrothermal Models: A Comprehensive Review

“…Additionally, saturation pressure is only dependent on temperature, as shown by the dotted line in Figure 8. As a result of this graphical method, by comparing the vapor saturation and distribution, in the upper part of the roof, the vapor pressure is higher than the saturation vapor pressure, so the blue highlighted color in Figure 8 shows where condensation can be expected [103,104]. This simple, one-dimensional, steady-state calculation approach has been implemented in standards and codes in Europe, the USA, and Canada.…”

Assessment of the Annual Transmission Heat Loss Reduction of a Refurbished Existing Building with an Advanced Solar Selective Thermal Insulation System

“…The ray tracing methodology presented in Section 2.3 based on the model introduced in [17] computes the radiation distribution in the LCE for each mean solar position, which subsequently serves as an input variable for the dynamic heat transfer simulation. Common building simulation software, such as WUFI ® or IDA ICE, often uses one-dimensional model equations [30][31][32] without any ray tracing simulation capability to compute the heat transport in wall structures. Therefore, in order to utilize the solar selective properties of SATIS in 1D simulation tools, a simplified computational methodology is required.…”

Influence of the Water Vapour Permeability of Airtight Sheets on the Behaviour of Facade

“…If all the variables have to be taken into account (influence of solar radiation, incidence of rain on vapour migration and phenomena related to the drying of structures), the dynamic method must be used. However, in this study, to distinguish between cases in which condensation does or does not appear, the static regime can be used, as this method is more conservative for the construction typologies studied [36]. Cascione et al [36] carried out a study of condensations in different building typologies in two Italian cities using both methods.…”

“…However, in this study, to distinguish between cases in which condensation does or does not appear, the static regime can be used, as this method is more conservative for the construction typologies studied [36]. Cascione et al [36] carried out a study of condensations in different building typologies in two Italian cities using both methods. From this, they found that with the method of the UNE EN ISO 13788:2016 standard, condensations occur in cases that do not occur with the method of the UNE EN 15026:2007 standard.…”