The classification of fa? ade systems by “morphological” aspects, i. e. form, dimension, construction, material, function etc. led to a great variety, (23 parameters and up to six variations per parameter in the morphological box). The number of classified solutions could dramatically be reduced, if only the physical properties were considered, which had an influence on the energy demand. It was possible to reduce the 23 parameters to six energy relevant parameters: window/fa? ade (Awindow), mean heat transmittance of fa? ade (Um), heat gain coefficient of glass (gG), heat gain coefficient of shading devices (FC), light transmittance of glass (TL), equivalent air change rate (neq). For each parameter there are defined five equidistant values, the bandwidth between lowest and highest value given by minimal building standards and best practice solutions (Table 1).

Table 1. Equidistant steps and bandwiths of relevant parameters (U-values of opaque and transparent elements

were combined to a mean faqade value)

In total there were 15,625 facade combinations to be simulated by TRNSYS for each of the (four) major fa? ade orientations. All simulations were carried out under the same boundary conditions, such as office floor plan and weather data.