Retro-commissioning (RCx) plays a vital role in energy conservation by regularly assessing and fine-tuning building systems to ensure optimal energy performance, reduce energy waste, deliver cost-effective savings with long-term sustainability. The EMSD collaborated with the Hospital Authority (HA) and the Hong Kong Green Building Council to conduct a RCx study of the chiller at the Prince of Wales Hospital (PWH), which received the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Hong Kong Chapter Technology Award 2025 in March this year, and later won the ASHRAE Region XIII (Asia Pacific) Technology Award in June.
Air-conditioning and ventilation account for the largest portion of electricity consumption in public hospitals. One approach to saving electricity is RCx, which identifies opportunities to enhance the operational efficiency of existing systems, allowing clients to save energy without replacing equipment, with lower investment costs and a shorter payback period. The award-winning study focused on the central chiller plant at the Main Clinical Block and Trauma Centre of the PWH. The team analysed the historical operating data for the units and optimised the control system, such as further adjusting the water supply temperature, pump pressure, and the number of operating units during periods of lower air-conditioning demand. The challenge of this project lies in the fact that the hospital’s air-conditioning system has stricter performance requirements compared to typical office buildings, involving operating theatres and various medical equipment with higher temperature and humidity control requirements, thus making the design and implementation of related energy-saving optimisation plans more difficult.
The study was completed in August 2024 and implemented by mid-2025, with an estimated annual energy saving of 800 000 kWh, equivalent to the annual electricity consumption of over 200 Hong Kong households, and an expected payback period for the costs of RCx within two years.
The EMSD will continue to conduct RCx for air-conditioning and ventilation systems for more buildings to enhance energy efficiency, contributing to Hong Kong’s long-term carbon neutrality goals. If clients wish to learn more about the RCx project, they are welcome to contact our Senior Engineer, Mr Yip Wai-tong, at 2808 3383.
