Analysis of wind-driven rain characteristics acting on building surfaces in Shanghai based on long-term measurements

Wind-driven rain (WDR) is a critical boundary condition for the thermal and moisture coupling calculations of buildings, and understanding its distribution patterns on facades helps to better design building envelope structures and reduce humidity-induced problems. Given that WDR research in China is limited to a small number of numerical simulations, with field measurement data especially lacking, long-term and high-time resolution WDR measurements on a building module were launched in Shanghai. This research aimed to explore the WDR characteristics of building facades under meteorological conditions in the Shanghai region and compare the accuracy of existing semi-empirical models of WDR through measurements. The results show that when the angle between the inflow wind direction and the vertical direction of the wall facade increased, the WDR capture ratio decreases, and the increases in rainfall amount and wind speed contributed to an increase in WDR amount. The measurement relative errors had a negative exponential relationship with the WDR amount in this research. Compared to non-rainy conditions, the temperature during rainfall was 4.0-5.6 degrees C lower, and relative humidity was 9.8-21.8% higher. WDR results were compared with two semi-empirical models, which indicated that the ISO model was 0.5-0.8 times that of the measured values, while the ASHRAE model was 1.3-2.4 times greater. The collected data can provide a valuable and unique reference for WDR semi-empirical models and computational fluid dynamics simulation validation in China.