An improved procedure for determining skylight well efficiency under diffuse glazing

This paper presents a simplified procedure for determining skylight well transmission efficiency for vertical and splayed sky light wells when the glazing is assumed to be diffuse. The radiative exchange form factor between the top and bottom openings of the well is the key parameter that must be determined in applying this new approach. Equations and graphs for accurately determining this form factor are provided An approximate well efficiency is then determined using a simple three-surface flux transfer system, to which a correction factor is applied to bring the calculated well efficiency into close agreement with a more accurate five-surface flux transfer model that addresses a variable wall luminance across the height of the well This procedure provides a more accurate result than the existing graph in the IESNA Lumen Method for Toplighting (Rea 2000), and permits expansion of that method to splayed skylight wells of assorted geometries.