Observation Experiment of Wind-Driven Rain Harvesting from a Building Wall

Abstract

Rainwater harvesting is generally assumed to collect rainwater from the roof or ground. However, this study shows that this structural limitation of rainwater harvesting can be overcome by employing a building wall. The rainfall on a building wall is called wind-driven rain (WDR), which is the target for the rainwater harvesting addressed in this study. To prove the possibility of WDR harvesting, this study prepared three different gauges to collect the rainwater from a building wall. These gauges are like miniature buildings used to collect the WDR on the building wall inside a storage tank at the bottom. The WDR harvesting gauges were located on the rooftop of the Engineering Building, Korea University, and a total of 15 rainfall events were observed during the rainy season in Korea from June to September 2020. Our analysis of the collected data confirms the significant role of the building wall in rainwater harvesting. For a building height of 0.5 m, the rainwater additionally harvested from the wall was about 40% that from the roof, which became about 70% for the height of 1.0 m and about 90% for the height of 1.5 m. In addition, Cho et al. (2020)'s empirical equation for estimating the WDR is found to be useful for estimating the amount of rainwater harvested from the building wall. The correlation coefficients between the measurements and estimates were estimated to be high as 0.94, 0.92 and 0.91 for building heights of 0.5 m, 1.0 m, and 1.5 m, respectively.