Controlling double-skin façades with inclined louvers for natural ventilation: An experimental and theoretical study

Naturally ventilated double skin façade (NVDSF) is an emerging renewable energy system that utilizes external solar radiation to enhance the natural ventilation of buildings to save energy. Louver is one of the most effective and convenient passive control methods for NVDSF systems. However, the control mechanisms of the louver on its natural ventilation performance are still unknown. Therefore, this study experimentally and numerically investigated the effect of different inlet and outlet louver inclinations (within 15–90°) on the natural ventilation performance of NVDSF at a solar radiation intensity of 500 W/m2. The experimental results showed that a higher inlet louver inclination increases the thermal buoyancy driving effect of the NVDSF and enhances the airflow in the cavity. However, a higher outlet louver inclination increases the airflow resistance at the outlet, resulting in a lower outlet air velocity. The optimal louver combination that provided the highest volume flow rate was an inlet louver inclination of 60° and an outlet louver inclination of 90°, leading to a 56.4 % increase in outlet volume flow rate compared to the scenario when the outlet and inlet louver inclination of 45°. A theoretical model of the NVDSF outlet volume flow rate at different outlet and inlet louver inclinations was developed. Based on the model, the mean relative error between the predicted volume flow rate and the experimental value was 13.1 %. This study experimentally investigates the operation strategy and optimal configurations of NVDSF with inclined louvers, providing guidance for the optimized design of NVDSF.