Simulation numérique des transferts de chaleur et d’humidité dans une paroi multicouche de bâtiment en matériaux biosourcés

摘要

In a context of energy efficiency and durability in the field of building, the understanding of hygrothermal behaviour of building materials, especially hygroscopic ones, is essential. This study aim to understand and model heat and moisture transfers in a multi-layer building wall made of biosourced materials. We focus in particular on hysteretic phenomena observed on sorption isotherms. A one-dimensional numerical model developed with the COMSOL Multiphysics software is used to simulate transient temperature and vapour pressure in three situations. The first one is about the hygrothermal behaviour of materials, highly hygroscopic (hemp concrete) and lowly hygroscopic (lime-based plasters), exposed to several cyclical variations of relative humidity. A good agreement is observed between simulated and measured values of relative humidity, temperature and moisture content. However, results are highly sensitive to hydric properties. Then, a study is performed on an instrumented hemp-concrete wall built in a bi-climatic chamber and exposed to simultaneous temperature and relative humidity variations. The confrontation between measured and simulated values shows the importance of initial moisture content.