Hybrid equivalent model algorithm for the prediction of glazing angular properties

Daylighting and energy consumption evaluation for actual rooms requires knowledge of the luminous and energetic parameters of the fenestration, both at normal and off normal incidence. In the case of coated glazings, the off normal parameters can be achieved only with very complex measurements. The Hybrid Equivalent Model Algorithm allows the prediction of the fenestration characteristics solely on the basis of the transmittance and reflectance spectra, measured at normal incidence, without need of any information about the coating composition. In this paper, the algorithm effectiveness is tested on single, double and triple-pane glazings by applying it to a set of synthetic coated glasses, inspired by :real specimens; the variety of the considered coatings makes this set quite representative of the industrial production. The results are very encouraging: for 19 samples, on the 22 considered here, the mean deviation of the g-factor from the true values is less than 1%; for the remaining 3 it is not larger than 3.7%, and probably it could be reduced by further refining of the hybrid model because these 3 samples belong to the same product class. (C) 2002 Elsevier Science B.V. All rights reserved.