Daylight transmittance through Expanded Metal shadings

Abstract

Due to the substantial need for energy efficiency, the daylight performance of building envelopes is a key issue in sustainable architecture. A frequently used shading system consists on static expanded metal meshes (EM). As a very prominent textural facade element, expanded metal is widely used as both a cladding and static shading device. One first aim is to provide a sufficient description of EM, including fabrication, possible usage and overall properties. This includes a set of parameters needed to control accurately the complex geometry of EM. Those parameters are also useful to get reliable 3-D computer models of EM. The main objective of this paper is to assess, describe and compare EM light transmittance performance as a shading device. We were specifically looking to determine the influence of parameters such as geometry, colour, position and direction of incoming light on the shading performance. The research is based on BSDF simulations via Radiance and experimental data provided at a previous laboratory stage. We have simulated and compared the performance of various EM shading devices for a south exposed facade in Madrid in most characteristic times of the year: solstices and equinoxes, as well as midday transmittance throughout the year.