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Abstract: A human being spends approximately one-third of his/her life in sleep. Sleep can help people overcome tiredness, and is very important to one''s memory. With the gradual understanding of the influence of thermal parameters in a sleeping environment on the quality of sleep, different thermal environmental control approaches, such as electric blankets, space heating for cold sleep environments and circulation fans and air-conditioning for hot sleep environments, have been used to maintain a suitable thermal environment for sleep, so that sleep quality could not be adversely affected. In this review paper, firstly, the concept of thermal comfort applicable to sleeping environments is introduced and the relevant studies reviewed. Secondly, the review of the two important issues related to air-conditioning for sleeping environments in tropics and sub-tropics, i.e., night-time space cooling load characteristics, and ventilation requirement for a sleeping person, is presented. Thirdly, different air-conditioning systems used in sleeping environments and these related energy consumptions are reviewed, with an emphasis on bed-based (task/ambient conditioning) TAC applicable to a sleeping environment, which could help save more energy without scarifying the thermal comfort of a sleeper and indoor air quality. Finally, a number of research areas where future studies are needed are reported, including developing optimized control strategies for air-conditioning systems for sleeping environments according to night-time space cooling load characteristics, and new TAC systems applicable to a sleeping environment for greater energy saving. [Copyright &y& Elsevier]

Abstract: In general, a proper balance of temperature and humidity control is essential for efficient datacenter operation and is integral to protecting the significant investment in computer and network technology in datacenter facilities. However, the rising costs of energy and the drive to be green are resulting in a greater demand to conserve energy. One method of reducing facility costs for a chilled water plant is by adding an economizer. The purpose of this study is to develop energy models of the most common economizer systems. A normal chiller plant with an air-side economizer and a water-side economizer are compared. Results show that outdoor conditions influence facility energy consumption. This paper provides terminology and definitions for the two different types of economizer modes and compares their energy performance against key datacenter attributes in temperate or subtropical regions. The electrical end use breakdown and the Power Usage Effectiveness (PUE) value for a typical year were estimated. The water-side economizer made it possible to achieve a maximum energy performance improvement of about 16.6% over the reference base cooling system, whereas the air-side economizer made it possible to achieve about 42.4% improvement. [Copyright &y& Elsevier]

Abstract: Hainan province is the only tropical and island province in China, with the unique climatic and geographical features. It has a different energy performance in public buildings from those in the inland areas. This paper investigated the current situation of energy consumption of the sampled public buildings, including 26 hotels, 24 office buildings and 7 department stores, through analyzing utility billing data, on-site survey and measurement, and site operational records. The breakdowns of energy consumption found out that the electricity dominated the energy consumption for all the sampled buildings and the air conditioning system played a key role in the energy consumption of major building services. By analyzing the main factors for building energy consumption, the annual average energy use indexes were calculated to be 141.63kWh/m2, 87.70kWh/m2, and 166.95kWh/m2 for hotels, office buildings and department stores, respectively. Besides, the comparison between Hainan province and other areas revealed that the building energy consumption of this tropical province was at a low level. Because indoor environment quality can influence the health and work efficiency of humans in buildings, field tests on the indoor environment quality were also carried out, and the performance of indoor environment quality was rated. [Copyright &y& Elsevier]

Household air conditioners (ACs) with cooling capacities of less than 6 kW are popular in the tropics but are highly energy intensive because of the humid ambient condition. The hybrid dehumidifier-AC concept was studied here to improve the energy efficiency of such systems. Feasibility of the concept was investigated by looking at the design complexity, expected performance, and economic aspects. From the design analysis, it was concluded that small desiccant wheels are most practical for portable and window ACs, while no dehumidification concept was found ideal for split-type room ACs. Performance of the system was benchmarked with data from a 6.4 m2 room under tropical ambient conditions with air change rates of 1-4 changes per hour. It was found that an average load reduction of up to 8.1% was obtainable. The corresponding potential power saving was 9.4%. The performance data were then used for the economic analysis. It was found that the hybrid system is financially attractive mostly when cooling capacity, usage rate, and electricity price are high. Furthermore, the system should have a cooling capacity of at least 4 kW and 4 air changes per hour to be financially justifiable, particularly in places with low electricity prices. [ABSTRACT FROM AUTHOR]

Air-conditioned offices in the subtropics are recommended to operate within specified ranges of indoor temperature, relative humidity, air velocity, and carbon dioxide concentration for thermal energy conservation. As environmental discomfort leads to productivity loss, this study investigates the impact of an indoor environmental policy on Grade A offices served by different airside systems in terms of energy consumption, thermal comfort, and productivity loss. Occupant thermal response is specifically considered as an adaptive factor in the evaluation of energy consumption and productivity loss. Simple Monte Carlo sampling technique was applied to determine the input parameters referenced from literatures for simulation. The findings indicate that the reduction of clothing value improves thermal sensation and should be addressed in the environmental policy to ensure a thermally comfortable indoor environment.Practical application: This study is a useful reference source for evaluating indoor thermal environmental policies for air-conditioned offices in subtropical climates. Implication of clothing value in thermal sensation should be addressed in the environmental policy to ensure a thermally comfortable indoor environment of air-conditioned offices. [ABSTRACT FROM AUTHOR]