Modeling Intensity Distributions of Advanced Daylight Systems Surrounded by Arbitrary Luminance Maps

Abstract

For more than a decade, daylighting optical devices (DOD) using reflection, refraction and diffraction have been used in commercial buildings. Some of these systems show considerable promise for south facing facades, as they can reject or redirect sunlight and diffuse daylight. However, their daylight performance is not clearly understood. Simulation tools employing Monte Carlo forward ray tracing are now available and can used to trace rays from the source (the exterior environment) through a devise and into the building interior. Two problems remain, however. The first is the generation of a ray distribution of the exterior environment. The second problem is the representation of the resulting daylight distributions at the DOD exit surface. There would be several advantages if an exiting ray distribution could be represented as an intensity distribution in narrow angular increments in a photometric file format. We shows how to generate ray representations of hemispherical luminance maps for exterior environments, introduce a method to determine intensity distributions for DODs, and discuss errors involved. Results of tests against measurements for a commercially available specular micro louver are reported.