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Sea water-cooled chilled water plants have been popular in Hong Kong and have been preferred for district cooling systems. This is generally recommended by policymakers and consultancies as a more energy-efficient option than cooling tower-equipped chiller plants. Often district cooling and sea water cooling (including lake water) is discussed synonymously as usually district cooling plants are large and generally only large plants are worth the hassle of sea water cooling. The argument of district cooling systems has always been the ability to concentrate capital to deploy better performing technology and the centralization of equipment to allow for maintenance and operation. All of this is supposed to make the plant more efficient, and these arguments may not be as true nowadays and there is an engineer's bias to build bigger and more complicated systems. The author would challenge these conceptions and explore the realities of district cooling and seawater cooling. This paper will argue that generally it is district cooling plants will be less efficient than multiple distributed chiller plants serving the same load at the same technology level and that centralization will result in an increased chance of catastrophic failure. There is however a window of opportunity where district cooling systems are competitive and desirable, this paper is intended to be a guide to assist in the decision if a district system and or sea water cooled system should be pursued. [ABSTRACT FROM AUTHOR]

Cooling towers have been installed on different roof levels due to a variety of reasons such as space limitations, leasing rights, and architectural features. For an open system, this is a height difference is inherently troublesome and engineers have used a variety of methods to address the potential issues. This issue is especially prevalent in Hong Kong where buildings tend to be needle high rises with limited real estate on the roof that is often shared between multiple tenants and where space is allocated on a first come first lease basis and thus uncoordinated cross over the placement of plant equipment is common. The failure of many such installations has resulted in the loss of condensing water as the lower cooling towers flood while the upper cooling tower dries up. In more extreme cases, air enters the system and airlocks the pumps causing a complete cooling system failure. While this is not a case study, the author has come across many such installations and has been commissioned to re-engineer the system to fix many of the issues in its operation. This paper will explore the common ways of installing and operating cooling towers at different height levels, the limitations, risks, and strengths of each approach. [ABSTRACT FROM AUTHOR]

Ongoing commissioning is important for improving the energy efficiency of large scale air conditioning systems. It should be an essential part of building operation and maintenance. However, normal ongoing commissioning is time-consuming and needs expert experience. This paper therefore presents a quick, streamlined ongoing commissioning method. Based on operation data logs stored by building management systems (BMS), this method can give primary evaluations on system performance and supply suggestions for operation optimization and equipment retrofit. This method has been applied in a shopping center in Hong Kong. The applications have been introduced in detail as examples to illustrate the method. [ABSTRACT FROM AUTHOR]

Common design guides on smoke management in atria will be reviewed in this paper. Different approaches used in those guides are outlined. It is observed that the engineering principles behind those design guides are basically the same, though the approaches might be different. Smoke ventilation appears to be a common approach for smoke management in an atrium. An acceptable smoke layer height can be kept, or at least the descending rate of the smoke layer could be reduced. Designs based on different guides are compared by referring to some real cases in Hong Kong. There are deviations among different guides even under the same fire scenarios. At the moment, these guides only give general design principles, not yet covering all atria, especially the tall ones in the Far East. In other words, only simplified design procedures for systems under some agreed fire scenarios in an atrium are outlined. Guidance on solving practical problems frequently encountered in atria apart from those cases is discussed, taking the huge development in the construction industry of China as an example. [ABSTRACT FROM AUTHOR]