Identification of the important parameters in thermal building simulation models

Two parameter screening techniques, a sequential bifurcation technique and a factorial sampling method, have been applied to a building thermal model, used to predict thermal comfort performance of a building in its design stage. Combined application of both screening methods revealed a set of 12 important model parameters out of a total of 81, explaining 94% of the variability in the model output. These important parameters were identified by the factorial sampling method on the basis of 246 model evaluations, while sequential bifurcation only needed 52 evaluations. However, the factorial sampling scheme was effective in identifying of not only the important parameters, but also the directions of parameter main effects and the severity of interaction effects. This additional information showed that isolated application of the sequential bifurcation method would have been unreliable, as satisfaction of the inherent assumptions could not be guaranteed. Only on the basis of proper knowledge of the sign of the parameter main effects, adequate clustering of important parameters and transformation of the model output, all obtained from the results of the factorial sampling scheme, reliable and economic application of sequential bifurcation was possible.