Simplied Solar Optical Calculations for Windows with Venetian Blinds

Solar gain through a window represents the most variable heat gain imposed on an indoor space. It is also likely to represent the largest heat gain of the indoor space. Shading devices like venetian blinds, roller blinds and drapes are routinely used to control solar gain through windows and their potential for reduction of building load and annual energy consumption is recognized to be large. As such, there is a strong need for models that allow shading layers to be included in glazing system analysis. In this paper, three sets of calculations are presented for a window with light- and dark-coloured venetian blinds using simplified models and computational procedures. For each of the three sets; hourly transmitted, reflected and absorbed fluxes are calculated for both summer and winter conditions. In the first set, the venetian blind is placed on the indoor-side of the window. For the second set, the venetian blind is placed between the glazings. Finally, the third set of results is obtained by placing the venetian blind on the outdoor-side of the window