Model for Multidimensional Heat, Air and Moisture Conditions in Building Envelope Components.

Purpose, hypotheses and relevance
Moisture and temperature levels and variations in time and space play a crucial role in degradation processes of building materials, such as silicate materials, metals and polymeric materials where also UV-radiation is a very important factor. An exterior wall can consist of more than 10 different material layers. Furthermore, a wall element is often inhomogeneous in the plane because of counteracting structural and insulating properties. The moisture and temperature conditions inside such a wall are highly dependent on the material combinations and the climate conditions on both sides of the wall.
The background and motivation for the project is that most damages that happen to building components occur in places with a complex geometry that cannot be handled correctly by today’s design tools. This could for instance be where different materials meet in joints and where conditions most
often have a multidimensional nature. Also apparently regular construction elements have multidimensional parts and features whose hygrothermal conditions should be considered better in the design of buildings, e.g. near beams and columns in common building elements. These loci often represent thermal bridges in the constructions, and they involve the assembly of different components and materials, so there is an increased risk of unintentional
airflow or accumulation of moisture. The combination of these factors too often lead to the degradation of materials.

Purpose
It is the purpose of the project to develop a computational model for multidimensional transient Heat, Air and Moisture (HAM) flow in building constructions.
The model should provide a suitable toolbox for fast and sound computations of moisture and temperature conditions in building components.
This project intends to produce a tool that enables the analysis of conditions leading to degradation of building components. Critical temperature and moisture conditions and UV-exposure are partly known and partly collected from field tests and controlled experiments in a laboratory environment.
It is the intention that with such a combination of models and systematic collection of empirical knowledge, it will be possible to predict better those degradation processes of building products, which are realised in practice.