Façade Photometrics: Luminance Distribution Analysis Through Building Skins

Abstract

This paper presents a novel technique to evaluate how building façades propagate light into interior spaces. Just as electric light photometry charts the luminous intensity around a light fixture, Façade Photometry, a term coined by the author for the method introduced in this paper, uses annual simulations and localized weather data to create temporally based luminance distributions. This photometric chart is a unique signature of a particular façade design located in a specific climate in a specific orientation. This method seeks to provide designers the ability to more easily compare the performance of complex and intricate glazing and daylight control systems. Current methods of obtaining annual luminance values require the collection of High Dynamic Range (HDR) images, an inefficient and time-consuming task; far from optimized for use by the design community. The method proposed in this paper uses a bi-directional measurement of daylight received by digital sensors arranged hemispherically in a black room, aimed at the façade. The results provide data on spatial luminance distribution, vertical eye illuminance distribution, luminance contrast, and glare index from different gazing angles. While further analysis of the method and comparison to human perception is necessary in order to understand the meaning behind the results, the method has the potential to become a streamlined tool to further aid designers in the pursuit of designing highly energy efficient and beautiful spaces.