Effects of modified near-infrared retro-reflective film on urban thermal environment

We investigated the specifications of a modified retro-reflective film for the window surfaces of buildings that reflects the near-infrared component of incident solar radiation upward toward the sky in order to reduce the indoor cooling load in the building and improve the thermal environment of the surrounding urban area. With the previous specifications, there were concerns that the near-infrared component, reflected upward away from one building, would strike the upper portions of neighboring buildings. To minimize this effect by reflecting as much radiation as possible back along the incident direction, we evaluated the modified film structure, replacing a saw-tooth section model with a pyramid-type microstructure model. In order to investigate its merits and quantitatively assess the impact of this technology on surrounding urban areas, annual simulations with this modified film were performed, using simple block model, actual city model and the results of an experimental study.