This paper proposes an effective means of achieving appropriate operation of a heating and cooling system by initial commissioning through simulation. In this study we considered a means of verifying the performance of the designed storage tank. We estimated the temperature stratification in the thermal storage tank by CFD analysis using the simulation results of the heating and cooling plant carried out in the design step. Moreover, we considered the temperature stratification state as compared with the CFD analysis results of the thermal storage tank and summarized the usability of the CFD analysis in the design step.

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This paper reports the experimental results on the reduced energy consumption and environmental improvement when a window shade filled up with gelled n-paraffin (i.e., phase change material window shade) was installed inside a double-skin facade. The test equipment of a 1/3 office model was exposed to the external climate in summer. The maximum surface temperature of the PCM window shade was 20 K lower than that of window shade made of metal. The improvement in the indoor radiation field was predicted. The equivalent solar radiation transmittance was reduced by up to 38%; thus, the PCM window shade was confirmed to reduce the cooling energy consumption. While the shade temperature was kept constant, the potential of the natural ventilation was measured by the velocity and temperature distribution of the jet that occurred at the upper part of the slit of the double skin. The driving force behind the natural ventilation with the PCM window shade at night found to be 4.0 times that with metal shade. In addition, the amount of heat discharged at night was increased 6.7 times. These results show that construction can be cooled with night purges, and that PCM window shade can reduce the energy consumption to convey air throughout the day.

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The present paper proposes an optimal operational strategy for an actual HVAC system with a seasonal underground thermal storage system using a simulation technique. The simulation is a powerful tool for the system because it is difficult to try various operational methods experimentally in the actual system because of the long heat transfer time underground. This paper develops the whole system simulation by connecting an underground thermal model, which can simulate the heat exchange between the ground and the pipes buried in the foundation piles, with models of mechanical components in the air-conditioning system. Case studies about the operational method of the system are conducted using the simulation. The optimum operational strategy found using the simulation, which is to minimize the energy consumption of the whole system, can reduce energy consumption by approximately 12% (30.2 GJ to 26.5 GJ) and improve system efficiency from 3.61 to 7.14 as compared with the values of the present operational method.

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The number of cases of individual system air-conditioning being adopted has increased increasing remarkably in recent years. Various reasons for this have been, such as the ease of design, individually measurable fuel and light prices, the simplicity of a fee collection charge, the facilitation of overtime work in a tenant building, and initial cost. However, because the indoor air-conditioning machines distributed and installed in the ceiling with the individual system, the indoor environment may be affected by microbial contamination because of the difficulty in maintaining sanitary conditions. In order to clarify the influence of the temperature and relative humidity (RH) on the mold multiplication characteristics inside an individual air-conditioner, a laboratory experiment was performed, and seven buildings were examined in situ. The results clearly showed that the growth speed of mold in an individual air-conditioning system quickly increased when a RH of 70% or more occurred more than 30% of the time. On the other hand, when the coefficient of variation for the RH exceeded 10%, the mold index of an individual air-conditioner became small, and mold growth was controlled.

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