Effect of Textile Properties on the Bidirectional Solar-Optical Properties of Shading Fabrics

Abstract

This paper presents an experimental approach to and preliminary results of measurements of bidirectional solar-optical properties of shading fabrics. Transmittance and reflectance profiles for three woven and three knitted fabrics are presented as a function of altitude and azimuth angle for selected incidence angles of simulated direct solar radiation. The woven fabrics exhibit transmittance profiles that are sharply peaked in line with the incident beam. At normal incidence, woven fabrics with transparent yarns result in high peak transmittance of approximately 41%, whereas opaque yarns and dense structures result in low peaks of 0.5–2%. All of the wovens tested exhibit low reflectances of 1–2%. Knitted fabrics also show sharply peaked transmittance profiles in line with the incident beam. However, the open knits have peak values of up to 63% at normal incidence, whereas opaque knits show peaks of only 1–4%. Peak reflectance values for all the knits were low at approximately 1–2%, even with metallized yarns.