Using radiance to estimate transmitted solar radiation energy for thin perforated screens

Design of shading systems is essential, since they plays an important role in the modulation of daylight and solar gains. Yet, current simulation tools are not capable of providing accurate results for both daylighting and energy performance simultaneously, especially when complex geometries are present. This work investigates whether shading coefficients (SC) can be applied to evaluate the performance of thin screens, and it compares the results to those obtained through other methods, such as the use of a fixed transmittance value over the whole year. Results showed that hourly SC can take into account the variability of total transmitted solar radiation throughout the year. As a result, the cooling energy reached reductions of up to 22 % in comparison to the use of a fixed transmittance value. SC also enabled the assessment of inter-reflections within the PS-glazing system, especially those resulted from varying the distance between the PS and glazing.