Assessing the distribution and mitigation effects of wind-driven rain load on buildings with vertical louver shading facades

Wind-driven rain (WDR) is a critical moisture source threatening building envelope durability. While substantial research has focused on quantifying WDR loads on bare facades or isolated elements, a significant gap remains in examining WDR resistance in building envelope systems from a spatial-morphological perspective. Vertical louver shading facades are widely used in hot-humid regions for solar and thermal control, yet their WDR mitigation potential remains unexamined. The study investigated a six-story building with vertical shading louvers in Guangzhou through field measurements and numerical simulations, assessing the influence of meteorological and geometric parameters on WDR distribution and mitigation effects across interior facade and floor surfaces. Results indicated that the shading facade effectively modulates WDR, yielding a catch ratio (η) of 0.08–0.20 and inducing raindrop size sorting. Wind speed dominates WDR distribution, raising the facade η while lowering that on the floor. The wind direction governs the spatial distribution of η, dictating the location and asymmetry of high-deposition zones. The influence of rain intensity saturates at torrential level. Geometric parameters alter local flow: smaller cavity depth increases facade wetting, larger depth raises floor wetting; lower width to gap ratio concentrates wetting centrally, higher ratio shifts raindrops sideways; higher rotation angles weaken shading and increase WDR load. Compared to a bare facade, the shading facade achieves over 50% mitigation on the rear facade but underperforms locally versus a buffer zone facade. The research clarifies how vertical louver shading facades regulate WDR through combined obstruction and aerodynamic effects, defining key parameter influences to support climate-adaptive facade design.