Skylight wells: A finite element approach to analysis of efficiency

Skylight well efficiency (WE), a measure of the overall light transmittance of a skylight well, is influenced by the intrinsic characteristics of the well, such as its geometry and the visible reflectance of all its inner boundaries. In this study, a finite-element approach is used to model the distribution of the luminous energy inside square skylight wells with varying splay angles, height-to-width ratios, well-wall reflectance and effective reflectance of the glazed cover. Resulting efficiencies are compared to the results published by Serres and Murdoch where the skylight well efficiency was evaluated analytically on the assumption that the well-wall exitance is uniform across each surface irrespective of the depth of the well. The finite-element approach showed differences of up to 6% compared to the uniform exitance approach.