Object of this study was the development of a method for the one and two-dimensional calculation of the simultaneous heat and moisture transport in building components, using simple parameters. For this purpose, we first examined closely the moisture storage and transport mechanisms and their effect on heat transport. We disregarded moisture movements based on air flows, gravitation, hydraulic pressure differentials as well as osmotic or electrokinetic effects.

Moisture storage in building components is divided into three regions. The first region is characterized by hygroscopic equilibrium water contents (sorption isotherms). In capillary-active materials, this is followed by the super-hygroscopic region with water contents up to free saturation. In this region, the equilibrium moisture depends on the capillary vacuum in the water-filled pores or the relative humidity over the pore water. This dependence, which can be determined with measuring techniques, forms the basis for supplementing the sorption isotherms for high water contents. This results in a steady storage function which can be defined throughout the entire moisture region of 0-100% relative humidity. Water contents above free saturation are characterized by a third region, in which there are no more equilibrium states. The building material is supersaturated, i.e. the relative humidity, regardless of the water content, is always 100%. Using results from the literature as well as our own findings, we analyze the significance of the temperature dependence and hysteresis of the moisture storage function for moisture storage calculations. For the determination of the moisture storage function, we provide a simple approximation which is sufficiently accurate in cases without liquid transport across layer boundaries.

• governing equations for heat and moisture transfer : simplified 2D
• HAM: computer models
• HAM: theory and modelling
• liquid transport, moisture diffusivity

1. Calculation of heat and moisture transfer in exposed building components
2. Combined effect of temperature and humidity of the detoriation process of insulation materials in ETICS
3. Flexible vapor control solves moisture problems of building assemblies - smart retarder to replace the conventional PE-film
4. Moisture buffering effects of interior linings made from wood or wood based products
5. Mold growth prediction by computational simulation
6. Simulation of indoor temperature and humidity conditions including hygrothermal interactions with the building envelope
7. Two-dimensional transient heat and moisture simulations of rising damp with WUFI 2D
8. Uncertainty of hygrothermal calculations
9. WUFI-ORNL/IBP - A North American Hygrothermal Mode