The aim of this research project was to evaluate transient thermal and fluid mechanical simulation models by means of on-site measurements in order to obtain information concerning the importance of the various extremely important base parameters of these very complex models of calculation. From October 2001 to September 2002, climate and flow conditions were measured on and in the glass facade of the new Federal Institute of Social Education building completed in 1998 in Baden near Vienna and analysed as to their correlation with the results of parallel numerical simulation calculations. It was shown that the basic version of the TRYNSYS software package lends itself well to describing the thermal situation in the space between the facade layers. The findings may be taken as a base for further development of the calculation model for more complex facade structures with partially transparent outside walls (double facades). The CFD (Computational Fluid Dynamics) calculations performed with the aid of the FLUENT software package also correlated well, in part, with the measurements, although they are more suited for scientific applications than for construction practice due to the considerable hardware requirements and duration of computing.