The effects of moisture movement and residual moisture content are becoming a recognized part of a performance based design of buildings. Despite the long-time existence of a basic 3-D formulation of heat and mass transfer within porous materials, the generalized hygrothermal behavior of construction elements that contain hygrothermal bridges and/or air voids has not been studied. Neither have the processes, which occur at the interfaces between different materials, been investigated. Relying on basic energy and mass conservation principles, a general integral form of presentation was applied to establish the coupled heat and mass transfer field equations, which were further transformed to a discrete set of algebraic equations. This form of presentation is more suitable for treatment of irregular regions, such as material interfaces and internal air voids. To treat these regions, specific mathematical procedures were implemented. Two Software packages were written to simulate the evolution of moisture content in non-homogeneous flat planar walls, without and with air voids. Finally, the results of modeling are presented for both types of constructions, thus enabling one to analyse a hygrothermal behavior of irregular wall's regions. building material [4 to 9]. Despite the long-time existence of a basic 3-D formulation of heat and mass transfer within porous materials, the generalized hygrothermal behavior of construction elements that contain hygrothermal bridges and air voids has not been studied yet. Neither have the processes, which occur at the interfaces between different materials, been investigated. Moreover, the effects of commonly existing air-voids (in the form of large hollow-cores or small deffects) within the materials composing the wall, or at the interfaces between the materials (as usually stems from the construction methods for the jointing), have not been studied either. This paper is devoted to the mathematical modeling and numerical solution of the moisture-content evolution in walls with hygrothermal bridges, including the case of a construction with air voids, concentrating mainly on methods of mathematical treatment of irregular wall's regions.

• HAM: theory and modelling

1. Air leakage of curtain walls -- diagnostics and remediation
2. Patterned mold growth on rendered facades in Israel - A consequence of substrate thermal insulation
3. Research and development needs for better implementation of the performance concept in building