Study on the influence of retroreflective materials on the “secondary reflection” on the room above the horizontal sunshade

Existing studies on horizontal sunshade systems mainly focus on the influence of the sunshade on the room under or inside the sunshade systems. Meanwhile, the top surface of horizontal sunshade, especially those with mirror surface or made of metal, reflects solar radiation into the indoor and surroundings, resulting in "secondary reflection". This paper mainly focuses on the influence of secondary reflection on the room above the sunshade, using DesignBuilder software to conduct numerical simulation analysis and building architectural model for field measurement. Results from simulation and field measurement both prove that mirror materials increase secondary reflection reflected into the indoor. Moreover, results from experiments show that retroreflective materials decrease secondary reflection reflected into the indoor. At low latitude, the application of retroreflective materials on the top surface of horizontal sunshade effectively reduces the adverse influence of secondary reflection on the room above the sunshade.