Water management is the new trend in civil engineering. Since it is difficult to ensure perfect vapor- and watertightness of building components, a limited moisture ingress is acceptable as long as the drying process is effective enough to avoid moisture damage. Recent computer models for the simulation of heat and moisture transport are valuable tools for the risk assessment of structures and their repair or retrofit. Unventilated, insulated assemblies with a vapor-resistant exterior layer can accumulate water because winter condensation and summer drying are not balanced. The balance can be re-established if the vapor retarder is more permeable in summer than in winter. Parametric computer studies have defined the required properties of such a vapor retarder. Developed according to the computed specifications, the smart vapor retarder shows a seasonal variation in vapor permeability of a factor of ten. The secret of this behavior lies in the humidity-dependent vapor diffusion resistance of the film material.

• smart vapor retarder : film material with permeance depedent, computer simulation

1. A new model for mould prediction and its application on a test roof
2. Ecological insulation materials - does sorption moisture affect their insulation performance?
3. Effect of interior and exterior insulation on the hygrothermal behaviour of exposed walls
4. Moisture risk assessment of roof constructions by computer simulation in comparison to the standard Glaser-method
5. More moisture load tolerance of construction assemblies through the application of a smart vapor retarder
6. Smart vapor retarder: an innovation inspired by computer simulations