Performance analysis of domestic rainwater harvesting systems under various European climate zones

Domestic Rainwater Harvesting (DRWH) is recognized as one of the widely accepted solutions to save potable water in buildings and has seen increasing popularity in Europe due to the improved reliability and understanding of system design and realization issues. In this paper, the performance of DRWH systems is examined in order to support their optimal design under various precipitation regimes. For this purpose 46 sites are selected within the European territory, equally distributed among 5 main climate zones based on the Köppen–Geiger classification. A behavioural model is implemented and non dimensional parameters are used to suitably compare the system performance under various environmental (i.e. hydrologic characteristics) and operational (storage capacity) conditions. Regression analysis is performed to investigate the relationship between hydrologic variables and the DRWH system performance examined in terms of the total water-saving efficiency index, E and the median value of the detention time, T. Results demonstrate that the Antecedent Dry Weather Period (ADWP) is the main hydrologic parameter affecting the system behaviour, while rainfall event characteristics (including event rainfall depth, intensity and duration) reveal weak correlations. Linear regression curves between the ADWP and the system performance are obtained with respect to each storage fraction.

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► Non dimensional parameters (S/Q and D/Q) are used to compare the performance.
► The cold and humid temperate zones show the highest water saving efficiency values.
► The Mediterranean and hot temperate zones show the shortest detention time values.
► ADWP is the main hydrologic parameter affecting the system behaviour.
► Linear regression curves between ADWP and performance indexes are obtained.