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Home> Promoting Energy Efficiency and Conservation> Water-cooled Air Conditioning Systems (WACS)

Water-cooled Air Conditioning Systems (WACS)


Water-cooled Condenser Plants The use of air conditioning in Hong Kong attributes a large proportion of our total electricity consumption, due primarily to its geographic location and economic activities. In 2000, air conditioning accounted for 32% of the total electricity consumption, of which 72% was consumed by non-domestic buildings. Our total electricity consumption grew by 52% from 1990 to 2000, while the electricity consumption by air conditioning had a growth of about 55% from 27,253 Terajoule (TJ) to 42,225 TJ during the same period. The use of air conditioning is expected to grow further in view of our increasing population and economic activities. We therefore need to take measures to improve our energy efficiency, in particular, on air conditioning. We should aim to reduce our energy demand and minimize the emission of greenhouse gases from our power generation plants to protect our environment through using energy-efficient water-cooled air-conditioning systems.


What is District Cooling System (DCS) and how it operates?

DCS is a centralized cooling system which provides chilled water to the air-conditioning system of user buildings for cooling purpose. The central chiller plant supplies chilled water and conveys it to the user buildings via underground chilled water pipe network.

Benefits to Society

Highly energy-efficient feature of DCS enables energy saving up to 35% compared with conventional air-cooled air-conditioning systems.
Environmentally friendly system as it consumes less electrical energy and hence produces less greenhouse gases and contaminants to the environment. Other environmental problems caused by the chillers, such as noise, vibration, and thermal plume are also resolved as no chiller plant is required in the end-user building.
Architectural benefits such as more freedom in architectural and facilities design, can be achieved from elimination of roof top chiller plant, resulting in roof space available for installation of sky garden or PV panels.

Benefits to End-users

Reliability and Quality are superior to conventional air-conditioning. With a team of professional engineers and supporting staff, DCS's computerized Central Chiller Plant ensures stable cooling supply to the end-user building at all time.
Save plant room space with an average of 70% for end-user building.
Flexible design to meet growth of cooling demand and extended service hours easily.
Save initial cost as no need to build its own chiller plant.
Save maintenance and operation cost due to less serviceable equipment and higher efficiency.

District Cooling System at Kai Tak Development

To further promote energy efficiency and conservation, the Government plans to implement a district cooling system at the Kai Tak Development to supply chilled water to buildings in the new development area for centralised air-conditioning. The DCS is the first project of its kind to be implemented by the Government in Hong Kong.

Charges for the Kai Tak District Cooling Services

According to the District Cooling Services Ordinance which was passed by the Legislative Council in March 2015, the effective rates for 2014/15 and the subsequent 2015/16 based on the adjustment formula as provided in the Ordinance are as follows:

2014/15 Charge Rates 2015/16 Charge Rates
Capacity Charge Rate $112.11 per kilowatt refrigeration per month $116.03 per kilowatt refrigeration per month
Consumption Charge Rate $0.19 per kilowatt-hour refrigeration $0.1959 per kilowatt-hour refrigeration
Remark: As announced by CLP, the annual rate of change in electricity tariff applied to the year 2015/16 is 3.1%

Technical Guidelines for Connection to District Cooling System

The Electrical and Mechanical Services Department (EMSD) has prepared a Technical Guidelines for Connection to District Cooling System, which aims to provide the technical requirements and arrangement for connection of district cooling system which is currently being developed at Kai Tak Development. Please click here to read/download the document [PDF format (925KB)].


EMSD completed three consultancy studies on Water-cooled Air Conditioning Systems in Hong Kong from 2002 to 2005, namely "Territory-wide Implementation Study of water-cooled Air Conditioning Systems in Hong Kong", "Implementation Study for a District Cooling Scheme at South East Kowloon Development" and "Implementation Study for Water-cooled Air Conditioning Systems at Wan Chai and Causeway Bay - Investigation". Please click here for the executive summaries of the study and other related reports.


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