Indoor domestic water demands are increasing rapidly in many cities of China, among the causes, water wastage due to overpressure outflow (OPO) at water distribution points in buildings, especially in high-rise buildings, is a factor that has not gained much attention. Field tests in 23 high-rise public buildings and laboratory tests were conducted to quantitatively evaluate the influence of water pressure on water consumption in buildings. The water-saving potential by adopting pressure reducing measures was theoretically analyzed and verified based on a case study. Results indicated that water consumption is closely related to water pressure and overpressure outflow is a very common culprit of water wastage in high-rise buildings. Pressure management measures, such as branch pipe pressure-reducing valves, can reduce water consumption in buildings and improve the comfortability of use as well. Based on the laboratory pressure–outflow characteristics study of different water appliances, water-saving potential of pressure reducing measures can be theoretically evaluated. Case study demonstrated a theoretical reduction of 19.4% in water consumption by adopting branch pipe pressure-reducing valves, an actual 14,773 m³ water (11.9% reduction) and 15,955 kWh embodied energy was saved in 2015 after the implementation of branch pipe pressure-reducing valves retrofitting measure. Therefore, despite the current measures of adopting high-efficiency water appliances and/or utilization of unconventional water resources in buildings, implementation of pressure management measures is highly recommended in designing water supply system for new high-rise buildings and reconstruction of water supply system in existing high-rise buildings, thereby, promoting water, energy saving, and development of green building.

Practical application: Water and energy saving in building is gaining more and more attention, however, water wastage due to overpressure outflow in buildings has not gained much attention. Based on field and laboratory tests, the water and energy saving potential in building water supply system were evaluated theoretically and further verified by a case study. Results indicate that pressure management measures such as branch pipe pressure reducing valves (PRVs) can reduce water and energy consumption in buildings. We strongly suggest that pressure management measures should be implemented in buildings, thereby, promoting water, energy saving, and development of green building.

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Water and energy saving potential by adopting pressure-reducing measures in high-rise building: A case analysis