Materials for outdoor curtains and awnings as a solution for improving thermal comfort and mitigating urban heat island

Outdoor modular structures with curtains and awnings may be an effective solution for mitigating Urban Heat Island, in particular for Cooling Dominated Zones (CDZ). The choice of suitable materials for outdoor shadings plays a fundamental role, especially in dense urban areas, because of high solar irradiance, low ventilation and high mean radiant temperature which might reduce the thermo-hygrometric comfort in summer conditions. For that reason, outdoor textiles materials with high solar reflectance upwards and low thermal emittance downwards could represent an effective microclimate mitigation strategy: textiles with low thermal emittance downwards, in particular, contributes to reduce the infrared radiation towards the covered area, which may ensure better thermal comfort conditions. Furthermore, materials with retro-reflective (RR) capabilities could help to reduce the amount of radiation that reaches the urban surfaces, as they reflect the incoming solar radiation mostly towards the incident beam direction. In this context, the present paper is aimed at studying textile materials for outdoor curtains and awnings in terms of their solar, radiative and RR characteristics, in order to improve human thermal comfort conditions under the coverings. For this purpose, a novel, glass fibre-based material for outdoor shading applications was analysed in terms of thermal emittance, spectral reflectance and directional reflectivity. Results of the experimental characterization show that the tested samples present a good global reflectance, while a high thermal emittance value has been observed. Directional reflectivity characterization reveals that all samples present a RR trend for incident light directions near the perpendicular.