Solar radiation-controllable double-skin façades to enhance natural ventilation for green buildings

Naturally ventilated double skin façades (NVDSFs) can effectively promote natural ventilation by utilizing solar energy to reduce energy demand. However, the optimum solar control strategies for NVDSFs with inclined louvers remain unknown, not to mention under various solar radiation intensities. To address this gap, this study investigates the coupled effects of the inlet louver (θi, 15°–90°) and outlet louver (θo, 15°–90°) inclined angles and solar radiation (300–700 W/m2) on its ventilation performance experimentally and theoretically. A solar radiation simulation was used to simulate solar radiation in this study. When the outlet and inlet louver blinds are controlled at the optimum angle, the NVDSF's natural ventilation performance increases by 33.1–63.5 % compared to the configuration when the inlet and outlet louver blinds are both at 45°. Additionally, experimental results indicate that solar radiation intensity affects the optimum design of controllable NVDSF with inclined louvers. We found that 500 W/m2 is an important irradiance to determine the optimum louver blind inclined angle: when solar radiation is low (≤500 W/m2), the optimum louver inclined angles are (θo = 90°; θi = 90°), and when solar radiation is high (>500 W/m2), the optimum combinations are (θo = 90°; θi = 60°). A theoretical model for natural ventilation in NVDSFs that accounts for both louver inclined angle and solar radiation intensity was developed and validated. This study demonstrates that controlling the outlet and inlet louver blinds with the optimum control strategy in the practical application of NVDSF can enhance natural ventilation.