scope:

INTRODUCTION

Humidity levels in building components and in indoor air depend on vapor transfers, on energy fluxes and resulting temperature levels and on air flows. The interactions between these phenomena are essential for the whole building (WB) Heat Air and Moisture (HAM) response. Indeed, the levels of relative humidity in the indoor air are strongly dependent not only on the moisture transfers between the air and the construction and moisture sources, but also on the correct analysis of airflows and of temperature levels, dependent upon proper energy balances.

When the impact of moisture on whole building energy response is considered, the first and essential step is to correctly represent the moisture balance, including vapor absorption and desorption from hygroscopic surfaces. In some practical applications, when only an estimate of the indoor climate is of interest, this can be done using simplified models for moisture buffering, such as Effective Moisture Penetration Depth (EMPD) model. However when the moisture level in constructions is of interest, the investigations require use of coupled heat and mass transfer models to describe the complex physics in walls. When a detailed field of moisture in the air or in the constructions is needed, Computational Fluid Dynamics (CFD) can help to get a precise prediction of the conditions. All these approaches, from EMPD to CFD, are complementary, and are of interest in HAM simulations of buildings.