Abstract

White polyethylene film marked as shade fabric with claimed 50-55% shade factor from embedded particles of titanium dioxide and UV neutralizing chemicals, when folded into 6 layers, absorbs 15% of solar energy and reflects 76%. Similar material knitted into a mesh that allows air passage absorbs 28% and reflects 61% when folded into 4 layers. If the absorption can be reduced to 5% and the reflection increased to more than 80%, the fabrics will be more effective for use in cities to reduce urban heat island effects and reduce global warming. The most reflective commercially available fabric reflects 92% and absorbs only 3% when folded into 2 layers. This sets an upper limit to what can be achieved because this material needs modification to resist UV damage. Climate change is creating an urgent need for development of better shade fabrics, mass produced frames to hold fabric and allow efficient replacement of damaged fabric, and better structures to support the frames. We outline ways of making highly reflective fabrics.

Keywords: Radiant Energy; Solar absorption; Microporous