Air quality, thermal environment, and several environmental controls were investigated in elementary school classrooms equipped with cooling systems in mild climate areas. Pupils' thermal evaluations and preferred temperature evaluations were obtained from a questionnaire. There were variations in control conditions of cooling systems at the beginning of summer while cooling systems were almost always operated in midsummer. There were classroom and seasonal variations in opened and closed conditions of windows and doors while cooling systems were operating. Outside windows were completely closed in many classrooms while cooling systems were operating in midsummer. When windows and doors were closed while cooling and heating systems were operating, there were air quality problems such as increase in indoor CO2 concentration. Excessive increase in indoor CO2 concentration could be avoided by opening windows and doors on corridor side. The neutral temperatures based on pupils' thermal evaluations changed seasonally and declined to outside temperatures compared with neutral temperatures of adaptive model in case less than 20°C.
