An innovative solar shading device for outdoor thermal comfort

This study illustrates the design, the development and the testing of an innovative solar shading device to be installed in outdoor urban spaces, with the aim to provide better thermal comfort during summer. The device consists in either a single or a double membrane tensioned through a flying mast and hung to existing poles and trees. Adjustable corner joints facilitate the installation and dismantling by the users and guarantee adaptation to most urban spaces. The double membrane configuration is proposed in order to reach a very low solar transmissivity, while an adequate air gap between the two layers allows cooling by ventilation. Two 25 m2 prototypes were created and installed side by side in an outdoor space in the Politecnico campus in Milan, Italy: a single layer device (based on a standard white membrane) and a double layer one (adopting a standard white membrane on the top and a low emissivity membrane on the bottom). The experimental campaign showed that the latter can provide better thermal comfort, since the mean radiant temperature under the double layer device was found to be lower (about 3°C on average and about 5°C at maximum) than under the single membrane.