THERMAL ENVIRONMENT IN OFFICE ROOM SERVED BY TASK/AMBIENT AIR-CONDITIONING SYSTEM WITH NATURAL VENTILATION

A task/ambient air-conditioning system with natural ventilation was installed in a high-rise office buildingin Osaka, Japan. This paper will report the results of the field measurements of indoor thermalenvironment and natural ventilation opening performances. From the thermal environmental aspect,the office is properly divided into working task zones and a general ambient zone so as to ensureboth occupants comfort and energy savings. Task air-conditioning is for satisfying individual thermalpreferences by using floor outlets. Ambient air-conditioning for the ambient environment is moderatelycontrolled with ceiling outlets. Natural ventilation substitutes for ambient air-conditioning during goodweather conditions. Natural ventilation openings are so shaped to diffuse the air along the ceiling andsend it as deep into the room as possible. The air flow from task floor outlets makes small temperaturedifferences between the upper space and the lower space in the task zones and gives occupantsthermal comfort. Sufficient ventilation can be ensured by this type of natural ventilation openings, andthe differences in the room temperature are small among various places due to air flow along theceiling surface. Heat consumption by ambient air conditioning was reduced by the natural ventilation by1/3 for the measurement period.