Simulation software needs to be validated before it can be confidently used for general investigations. This is done by comparing the results of simulations with experimental investigations of the thermal and hygric behavior of building components. The simulation results depend not only on the mathematical model used for the calculation, but also on the material properties and the weather data fed into the simulation. For this reason only test cases are suitable for which the detailed specimen assembly, the initial state and the boundary conditions have been well documented, and for which representative material data are available. If this is not the case, one runs the risk of replacing the missing data by conveniently chosen prejudiced guesses which do produce the desired results but which cannot reveal possible shortcomings of the model.

Unfortunately, the literature contains only very few experimental investigations which meet the above requirements. For this reason, some of the examples described here are based on unpublished experimental tests.
The ongoing work on the IBP outdoor testing field results in numerous well-documented investigations on the hygrothermal behaviour of building components exposed to natural weather. The comparison between experiment and calculation shows convicingly that WUFI is able to reproduce the complex effects which natural weather induces in a building component.

In addition, the purely mathematical correctness of the simulation software can be assessed by comparison with simple cases for which exact mathematical solutions are available.

Page created: 07 Aug 2000; last update: 24 Jul 2012