Impact of retro-reflective materials as urban coating: a theoretical study through simulations

The use of retro-reflective materials has been recently proposed as a strategy to mitigate the urban overwarming by increasing the solar irradiation reflected out of the urban environment. The hereby study focuses on the definition of a methodology to estimate the impact of retro-reflective coatings through a comparison with other surface treatments such as traditional and high-reflective materials. The case study is an urban canyon located in Milan (Italy). Firstly, the impact given by the geometry and the canyon’s orientation was investigated. Secondly, traditional, diffuse high-reflective and retro-reflective materials were applied to the façade and to the street. The outcomes demonstrated how the retro-reflective layer could perform better than the high-reflective when applied to the street in wide canyons, increasing by four times the solar irradiation reflected towards the sky dome. Conversely, the retro-reflective façade turns out to be more performant in narrow urban canyon models.