The energy consumption of pumps for hot and chilled water circulation cannot be ignored because it can be 10-20 % of the consumption of heating, ventilating, and air conditioning (HVAC) systems. This value generally accounts for a significant proportion of the total building energy consumption. In most HVAC systems, water is usually delivered by several centralized pumps, which may reduce the pumping system's energy efficiency because of unnecessary pressure loss. A decentralized pumping system is an alternative that only circulates the minimum water required by the respective terminal unit and can reduce the excess pressure loss. Therefore, such a system is considered effective in reducing HVAC energy consumption.

This study verifies the performance of a decentralized pumping system by conducting an experiment comparing centralized and decentralized pump systems in terms of their energy consumption for water delivery and their energy saving potential, under various water flow conditions. A reduced-scale experimental apparatus, which can represent an actual HVAC water delivery system, was used herein. A comparison was also performed using the theoretical pump power to avoid the effect of the performance characteristics of various pumps on the experiment. The following results were obtained: (1) The decentralized pumping system consumed lesser energy for water delivery than the centralized pumping system in both full and partial loads. (2) The decentralized pumping system particularly showed a higher energy saving potential when a variable water volume control was adopted in the HVAC system.