Influence of Changes of Material's BRDF on a Skylight Performance under Various Exterior Conditions

The article describes the results of the characteristics of a set of selected light pipes in different sky conditions. The first light source is the CIE Standard Overcast sky and the second is the partly cloudy sky with brighter circumsolar on the 21st of June. The light transmission efficiency of the light pipe with the ideal mirror-coated surface and a standard aluminum mirror is observed. Furthermore, differences in the use of the clear cupolas from the glass or from the PMMA are shown. The results show an unequable decrease in light transmission efficiency with increasing of skylight length.