A Computer Analysis of Window Shading Coefficients by Calculating Optical and Thermal Transmission

Measurements of solar heat gain through windows with different shading devices are rather complicated and need a calorimeter or some other kind of expensive equipment. The optical properties of a single layer can be found quite easily by spectrometer measurements in a laboratory. The paper describes a method to calculate the solar beat gain through combinations of layers outgoing from the optical data for the single layers. The ALGOL-program developed to solve this problem allows an arbitrary number of layers, anyone could be diffusing. The direct and total transmission through the combination, the reflexion, and the shading coefficients are calculated. The results of a theoretical investigation of different window combinations are presented. Key Words: Artificial lighting, daylighting, daylight distribution, fenestration, light transmission, polarization, shading coefficient, shading devices, solar heat transmission, solar optical properties, solar radiation, window shading coefficients.