Modelling the angular behaviour of the total solar energy transmittance of windows

The angle dependence of the total solar energy transmittance, the g-value, is addressed. Factors that influence the angular behaviour and possible ways to simulate it are discussed. A simple and accurate model to simulate the angle dependence is presented. Besides the data for normal incidence, the model employs two inputs: the number of panes in the window and the type of coating used. Detailed information about the coating composition is not required. The model gives good results and could easily be incorporated in building simulation programs or window selection tools where the angular dependence of the g-value for windows needs to be known. (C) 2000 Elsevier Science Ltd, All rights reserved.