Heating/cooling cost allocation is of growing concern in many countries because it contributes much to the energy conservation of central air-conditioning system. This paper intends to summarize the current studies and techniques on the heating/cooling cost allocation and discuss about the key problems to them. The contents mainly include the following parts: (1) probing into the methods of heating/cooling measurement; (2) establishing the calculation model for thermal billing; (3) presenting several typical systems for heating/cooling cost allocation. The significance of the paper is to help the engineers in this field have a good idea of the current development of heating/cooling cost allocation and promote the application of the relevant technologies to practice.

A large cooling system of residential building in Changsha City in China was investigated in the summer of 2003. The relationships among the controlled variables, uncontrolled variables and the chillers’ performance were obtained empirically with the test data. A model of optimal operation for the system was established based on these empirical relationships. A parameter, system coefficient of performance (SCOP), is presented to analyze the effect of energy saving of the cooling system. The results show that the energy saving is likely to reach as high as 10% by applying the optimal model to the cooling system.

Although variable-air-volume system (VAVS) can save much energy compared with other kind of HVAC system (e.g. constant-air-volume system (CAVS), fan-coil system (FCS)), it demands more investment. The rate of return of variable-air-volume system, which is closely related to the energy-saving rate of the system, ought to be taken into account by the engineers in the course of design. China has a wide territory and different climates that will impact on the energy-saving rate of variable-air-volume system. To help the engineers have a good idea of the rate of return of variable-air-volume system in different areas of China, it is necessary to establish such program that can evaluate the energy-saving rate of variable-air-volume system compared to constant-air-volume system and fan-coil system. In this paper, the specific energy models of the primary equipments in HVAC system are established, and the evaluation program for the energy-saving of variable-air-volume system compared to constant-air-volume system and fan-coil system are expounded. The parameters in the energy models, which may impact the validity of the evaluation program, can be obtained from the field-testing data or the performance data provided by the product manual. One small office building is taken as an example, the year-round energy simulations of the three kinds of HVAC systems (variable-air-volume system, constant-air-volume system and fan-coil system) of the same building have been made, and the energy-saving of the variable-air-volume system has been evaluated in six cities of China by the program. The evaluation program can also be used to analyze the energy-saving of variable-air-volume system in medium and big office buildings.

This study mainly explored the thermal comfort from the perspective of physiology. Three physiological parameters, including skin temperature (local and mean), electrocardiograph (ECG) and electroencephalogram (EEG), were investigated to see how they responded to the ambient temperature and how they were related to the thermal comfort sensation. A total of four ambient temperatures (21℃, 24℃ , 26℃ and 29℃ ) were created, while the other thermal conditions including the air velocity (about 0.05±0.01 m/s) and the air humidity (about 60±5 m/s) were kept as stable as possible throughout the experiments. Twenty healthy students were tested with questionnaire investigation under those thermal environments. The statistical analysis shows that the skin temperature (local and mean), the ratio of LFnorm to HFnorm of ECG and the global relative power of the different EEG frequency bands will be sensitive to the ambient temperatures and the thermal sensations of the subjects. It is suggested that the three physiological parameters should be considered all together in the future study of thermal comfort.

Energy-cost allocation systems apportion heating and/or cooling costs among the individual apartments in centrally-metered buildings based on various measures of relative energy use or thermal comfort. The most commonly used systems measure one or more parameters related to the thermal output of the terminal elements. In this paper, a new method for energy-cost allocation purposes was developed and studied. Taking advantage of the theory of frequency response, the individual apartments’ energy consumption for cooling in summer may be calculated using several parameters that include indoor and outdoor temperatures and the values of solar radiant-intensity. Experiments were done in this study, which indicates that the method of frequency response is fairly good in calculating the energy use of cooling.