Wind-Direction-Dependent Design Implications for Natural Ventilation Performance of Rain-Shield Monitor Roofs

Monitor-roof designs are widely used in buildings to enhance natural ventilation while protecting interior spaces from rain penetration. However, the ventilation performance of rain-shield monitor roofs can be significantly influenced by their geometric configuration and the interaction between wind-driven and buoyancy-driven airflow. In this study, computational fluid dynamics (CFD) simulations were conducted to investigate the ventilation performance of rain-shield monitor roofs under hybrid natural ventilation conditions. The effects of key geometric parameters, including the outlet height (Lz) and lateral spacing (Ly), were examined under different approaching wind conditions. The results indicate that ventilation performance is governed by the combined influence of wind-driven and buoyancy-driven mechanisms. Among the investigated configurations, an intermediate outlet height of approximately Lz ≈ 0.6 m generally provides favorable ventilation performance, while a lateral spacing Ly in the range of 0.6–0.8 m maintains effective airflow passage without excessive flow resistance. The findings provide quantitative guidance for the design of rain-shield monitor-roof ventilation systems in buildings operating under hybrid natural ventilation conditions.