STUDY ON EVALUATIONS OF THERMAL ENVIRONMENT UNDER CROSS VENTILATION AND AIRFLOWS FROM AIR-CONDITIONING SYSTEM AND ELECTRIC FAN

The purpose of this study was to clarify differences between evaluations of thermal environment undercross ventilation and airflows from air-conditioning systems and electric fans. Nine subjects evaluatedthermal sensation, thermal comfort sensation, airflow sensation and humidity sensation in anexperimental room in the summer of 2006. The surrounding ambient temperatures, relative humidity,and air velocity were measured simultaneously. The following results were obtained: (1) Airflowfeatures of three airflows were clarified on the basis of turbulence statistics and fluctuations in time andspace. (2) Changing frequencies of most sensation scales under cross ventilation were more thanthose under airflows from the air-conditioning system and their change ranges were wider. (3) Theratios of agreements between sensation scales over the whole body and those at respective body siteswere higher under airflow from the air-conditioning system than under cross ventilation, because flowdirections and fluctuations at respective body sites were different. Thermal sensation showed thelowest ratios of agreement of the four sensations. (4) When the air velocity was less than 0.5m/s, thecooling effects of cross ventilation for subjects were insufficient from the viewpoints of air velocity andairflow fluctuations based on the different results for four sensations. When the air velocity was morethan 0.5m/s, various air velocity changes and airflow fluctuations in time and space made subjects feelmore comfortable under cross ventilation than under airflows from the air-conditioning system.