Feasibility analysis of decentralized hybrid rainwater-graywater systems in a public building in Japan. (June 2021)

• Record Type: Journal Article
• Authors: Chen, Weilun; Gao, Weijun; Jiang, Jinming; Wei, Xindong; Wang, Rui
• Is Part Of: Sustainable cities and society. Volume 69(2021)
• Publication Date: 2021-06
• Subjects: Hybrid rainwater-graywater system -- Public building -- Water-saving -- Electricity consumption -- Economic analysis; Sustainable urban development -- Periodicals; Sustainable buildings -- Periodicals; Urban ecology (Sociology) -- Periodicals; 307.76
• DOI: 10.1016/j.scs.2021.102870
• Languages: English
• ISSNs: 2210-6707

Abstract

Highlights: Evaluating the feasibility of HRGs in public buildings based on the actual data. Performance of HRGs in the public building is superior to residential and commercial buildings. The economical unfeasibility of HRGs is caused by the waste of excess reclaimed water and high maintenance costs. The HRG can achieve economic benefits when the water tariff is higher than 880 JPY/m 3 or the non-potable water tariff is set to at least 200 JPY/m 3 . Abstract: The development of hybrid rainwater-graywater systems (HRG) has greatly alleviated urban water scarcity. However, the HRGs in public buildings have rarely been explored, which had limited the popularity of hybrid systems. In this study, a campus in Japan was selected to evaluate the feasibility of HRGs in public buildings. A water balance model with an hourly time step was performed to quantify the performance of the rainwater and graywater subsystems in the HRGs. Second, the electricity consumption of the HRGs was evaluated. Then, a detailed life cycle cost model was designed to calculate the economic benefit of the HRGs under the current and optimization scenarios. Finally, the results obtained are compared with HRGs in residential and commercial buildings to discuss the advantages of HRGs in public buildings. The results indicate that the promotion of HRGs in public buildings can not only achieve higher water-saving efficiency than other building types but also reduce electricity consumption in comparison with the traditional water supply methods. The economical unfeasibility of HRGs is caused by the waste of excess reclaimed water and high maintenance costs. HRGs in public buildings has the potential to be promoted preferentially in regions where the water tariff is higher than 880 JPY/m 3 or the non-potable water tariff is set to at least 200 JPY/m 3 .