This paper presents the benefit of natural ventilation of a roof cavity to reduce summer thermal loads ofa factory and, therefore, the cooling load due to air-conditioning systems with respect to various climatezones in Japan. A simulation program was developed to analyze the impact of cavity ventilation on theoperative temperatures of the occupied zones in a factory. Three climate zones in Japan: cold region(Sapporo), temperate hot-humid region (Tokyo), and subtropical region (Naha) were selected forcomparison. In an air-conditioning mode, two calculations of cooling loads were made.
The characteristics of a hybrid air-conditioning system, utilizing natural and mechanical ventilation, is investigated in an office setting. The characteristics of the indoor environment are examined with CFD(Computational fluid Dynamics) simulation under various conditions of incoming outdoor air. The control of the room air conditioning system (VAY system) is included in the calculation through changing the supply air volume to keep the task zone's temperature at a target temperature.