This study aims to investigate the actual conditions of indoor environment in schools, and to obtain fundamental information for ventilation design of school buildings. Indoor environment of two new elementary schools in Tohoku district of Japan were investigated. Temperature and humidity, concentrations of Carbon Dioxide(CO_2), ventilation airflow rates, concentrations of chemical substances, and the condition of opening the window and doors were investigated in the classrooms. As a result of this investigation, it was found that ventilation airflow rates was insufficient in classroom and CO_2 concentration was higher than 1500ppm in many hours due to the lack of window opening, and students hardly any opened the windows.
