High-Reflectance Technology on Building Façades: Installation Guidelines for Pedestrian Comfort

The focus of this study is on the impact of solar radiation reflected from the building façade to a pedestrian. The possibility of using high-reflectance technology on building façades was evaluated by using a two-dimensional simple building façade model. The effectiveness of applying retroreflective materials to building façades was also evaluated in regards to avoiding adverse effects on pedestrians. The ratio of diffusely-reflected solar radiation to a pedestrian from a given floor is proportional to the ratio of the angle of the reflective arc reaching a pedestrian from that floor to the angle of the reflective arc from the entire building. Specular reflection of solar radiation from the building façade is calculated by ray-tracing method corresponding to solar angle θ. In Japanese cities that are located at mid-latitudes, applying high-reflectance technology to a building façade at the fourth floor and above produces reflection of solar radiation that does not have adverse effects on pedestrians. High-reflectance technology is applicable on building façades above the fourth floor at any latitude, if we ignore a negative effect, since incident direct solar radiation to the building façade around noon is small at low latitude. Retroreflective material was considered for use on building façades below the third floor in order to avoid impacts on pedestrians from the reflection of solar radiation.