Today, the numerical solution of moisture transfer models in porous building materials has become a common tool for assessing the hygric behavior of building components. Use of these models necessitates the knowledge of the moisture properties: the moisture permeability and the moisture storage or capacity function. For use in numerical models, the moisture capacity or capillary pressure curve is commonly expressed by closed form analytical functions. The parameters of these functions are obtained by fitting the functions to experimental data.

In the building physics literature, different analytical functions were introduced. There exists however no agreement on the most suitable form for these functions nor is there consensus on the experimental procedure to follow, in order to obtain the necessary input data. Some authors prefer simple models, easy-to-use in practice, and limit the number of parameters in order to reduce the required number of experimental input data (K¨ąnzel, 1995, Hansen, 1986). Models frequently used in soil science emphasize more on the accuracy of the fitting procedure and simulate the capillary pressure curve by a sum of different functions (Durner, 1994 ).

In this paper, we try to compromise between accuracy and experimental effort. Therefore, we optimize both the functional form as well as the number of the required experimental data and determine the optimal location of these data. Essential is that the parametric function has to be appropriate for the whole moisture range. Therefore, we introduce the modality of the pore volume distribution as an important quantity, which determines the required number of analytical functions. We focus on the main wetting curve, which is of main interest in most building physics applications. The procedure is applied to two common porous materials: ceramic brick, which shows a strong capillary behavior with negligible hygroscopicity and calcium silicate, which is a highly hygroscopic, but less capillary active material.

• capillary break
• HAM: material properties : multi modal
• material property: pore size distribution
• Whole building HAM: humidity level in houses
• Whole building HAM: models

1. A comparison of different techniques to quantify moisture content profiles in porous building materials
2. A multiscale network model for simulating moisture transfer properties of porous media
3. A review of wind-driven rain research in building science
4. A simplified numerical model for rainwater runoff on building facades: Possibilities and limitations
5. Conservative modelling of the moisture and heat transfer in building components under atmospheric excitation
6. Determination of the isothermal moisture transport properties of porous building materials
7. Determination of the liquid water diffusivity from transient moisture transfer experiments
8. Determination of the moisture capacity of porous building materials
9. Driving rain on building envelopes II: representative experimental data for driving rain estimation
10. Microscopic analysis of imbibition processes in oolitic limestone
11. Modeling fluid flow in fractured media using continuum, network and discrete aproaches
12. Pedestrian wind environment around buildings: literature review and practical examples
13. Performance prediction for masonry walls with EIFS using calculation procedures and laboratory testing
14. Position paper on material characterization and HAM model benchmarking
15. Rainwater runoff from building facades: A review
16. Simulating non-isothermal water vapour transfer: an experimental validation on multi-layered building components
17. Spatial and temporal distribution of driving rain on a low-rise building
18. The influence of soil moisture in the unsaturated zone on the heat loss from buildings via the ground
19. Wind, rain and the building envelope: studies at the Laboratory of Building Physics, KULeuven
20. Wind-driven rain as a boundary condition for HAM simulations: Analysis of simplified modelling approaches  

1. A comparison of different techniques to quantify moisture content profiles in porous building materials
2. A comparison of the Nordtest and Japanese test methods for the moisture buffering performance of building materials
3. A quasi-steady state implementation of air convection in a transient heat and moisture building component model
4. Determination of the isothermal moisture transport properties of porous building materials
5. Determination of the liquid water diffusivity from transient moisture transfer experiments
6. Determination of the moisture capacity of porous building materials
7. Impact, absorption and evaporation of raindrops on building facades
8. In situ determination of the moisture buffer potential of room enclosures
9. Microscopic analysis of imbibition processes in oolitic limestone
10. Modeling fluid flow in fractured media using continuum, network and discrete aproaches
11. Position paper on material characterization and HAM model benchmarking
12. Qualitative and quantitative assessment of interior moisture buffering by enclosures
13. Review of mould prediction models and their influence on mould risk evaluation
14. Simulating non-isothermal water vapour transfer: an experimental validation on multi-layered building components
15. Wind-driven rain as a boundary condition for HAM simulations: Analysis of simplified modelling approaches