Optimizing water supply pump replacement in buildings of Hong Kong

Abstract

This paper investigates the pump efficiency of existing water supply systems in high-rise buildings in Hong Kong and provides economic justification for pump replacement by comparing the long-term energy cost savings to the initial installation costs. Energy consumptions of water supply pumps were measured with the pump efficiencies determined from the water consumptions of 20 water supply systems in buildings. The study results indicate that for typical pump motor ratings that range from 1 to 40 kW in a high-rise water system, with new pump efficiencies and annual pump efficiency drops that range from 0.68 to 0.74 and 0.012 to 0.028 respectively, a shorter replacement period can be justified on energy cost grounds for larger pumps with greater annual efficiency drops. Practical application: This paper exhibits numerical solutions of replacement period justified on energy cost grounds for typical pump motor ratings that range from 1 to 40 kW in a high-rise water system, with new pump efficiencies and annual pump efficiency drops that range from 0.68 to 0.74 and 0.012 to 0.028, respectively.