Benchmark experiments for moisture transfer modelling in air and porous materials

The presence of hygroscopic materials has a large impact on the moisture balance of buildings. Nowadays, HAM (Heat, Air and Moisture) models are widely used to investigate the role of hygroscopic materials on the performance of buildings, i.e. on the building envelope, the indoor climate and valuable objects stored within the building. Recently, these HAM models are being coupled to CFD (Computational Fluid Dynamics) models to study the moisture exchange between air and porous materials on a local scale (microclimates), or to BES (Building Energy Simulation) models which focus on the interaction between air and porous materials at building level. Validation of these numerical codes is essential to gain confidence in the codes. However, available experimental data are rather scarce. This paper describes the design of a new test facility for humidity experiments. A dedicated AHU system is used to provide well-controlled air (constant temperature and RH) to an airtight and well-insulated room-size test chamber. In one of the walls of the chamber a calcium silicate sample is installed. A step in RH of the supply air is imposed. Temperature and RH of the supply air, the room air and on various depths inside the sample are continuously registered during the experiments. Two types of experiments were carried out to validate a coupled CFD–HAM model and a coupled BES–HAM model. The temperature outside the test chamber was controlled and there was no temperature difference imposed across the chamber walls. Comparing the models with the measured data gave satisfactory agreement.