The accuracy of the building heating and cooling load prediction becomes a critical factor to achieve the optimal operation of the HVAC systems with thermal storage tanks. In this study, the cooling load prediction method based on the algorithm proposed by Yoshida was applied to an actual HVAC system with thermal storage tanks. And the accuracy of the cooling load prediction was verified through comparing predicted values with the measured values. By the simulation study, it was clarified that the prediction accuracy can be improved by revising the cooling loads based on the AHUs' running ratio and by using humidity at the near past. The EEP (Expected Error Percentage) of the cooling load prediction was improved substantially to 10.5%, which was 33.7% by original method. Moreover, the improved cooling load prediction method was applied to a real building. As a result of trial run of three months, the EEP of the daily summed cooling load was 9.8%, which shows this cooling load prediction method is accurate equal with methods evaluated by the benchmark test in past report.

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This paper reports the measurement results of indoor airborne microbial contamination in 9 hospital waiting rooms. Based on the measurement results, the design method on an air conditioning system to carry out improvement in the indoor air quality, especially in airborne microbes, was discussed from the view point of reducing the risk of mutual infection in hospitals. The main findings obtained from this study are as follows. Since the major sources of airborne fungi in waiting rooms are from the outdoor, it is important to appropriately maintain hospital environment in order to prevent the multiplication of fungi. On the other hand, as the major sources of the airborne bacteria in waiting rooms are patients themselves, it is necessary to reduce the mutual infection risk in hospitals by controlling indoor airborne bacteria contamination. Since the present performance of the air conditioning system is inadequate for filtrating and diluting indoor airborne microbes during reception period of a waiting room, indoor airborne bacteria concentration may become remarkably high. From the standpoint of reduction of mutual infections, it is important to install high performance equipment.

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The mechanism of the structure of indoor air and thermal environment in a hybrid air-conditioned office room is investigated by means of the trcer-gas measurement. In Summer, this office room is air-conditioned by task-ambient air-conditoning system. In interim period, ambient zone is naturally ventilated by the special ventilation openings located below the ceiling near the window. Local mean age of air, SVE4 (scale for ventilation efficiency No.4) and CRI3 (contribution ratio of indoor climate No.3) were calculated by means of tracer gas method to investigate the distribution characteristics of supply air and fresh outdoor air in the room. As a result of these investigations, task zone of around the occupants is clearly formed because the influence of UFAD is large in summer. In interim period, the occupants are greatly affected by natural ventilation than UFAD at the measured area.

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