Experiment of wind-driven-rain measurement on building walls and its in-situ validation

This study proposes an empirical equation that estimates the amount of wind-driven rain (WDR) on a building wall, meaning the amount of rainfall intercepted by a building wall. The proposed equation was formulated by analyzing the results obtained in previous studies on the vertical profile and spatial distribution of WDR on building walls. A laboratory experiment was conducted to collect WDR measurements for several building wall models that fit the proposed empirical equation. This study also observed the WDR for a miniature building located on the rooftop of the Engineering Building of Korea University. The proposed empirical equation was validated by comparing its estimates to in-situ observations. The results indicate that the estimations and the observed results are similar overall, but there are some discrepancies particularly when the WDR is small, with a correlation coefficient of 0.71 and root mean square error of 1.90 mm/hr⋅m². This study also estimates the amount of rainwater that can be collected from a building wall. The result shows that, even for a small building with a ratio of building wall to building roof of one, the amount of rainfall intercepted by the building wall can be up to 50% of the amount of rainwater collected on the building roof. This finding supports the idea that the WDR from a building wall can be a significant source of harvested rainwater.