Thermal comfort in Japanese schools

Comfort standards (ASHRAE 55, ISO 7730) specify exact physical criteria for producing acceptable thermal environments, which include temperature, air movement, and humidity limits that are often difficult to comply with, particularly in the subtropical climate of Japan. Changing expectations of comfort are important in evaluating comfort since schools in Japan are not typically air-conditioned. With the rapid growth of school buildings in the US and all over the world, provisions for comfort are critical to student performance and occupant well-being. Are these temperate-climate, air-conditioning based standards applicable in these locations? This paper builds upon previous thermal comfort work that has focused primarily on office environments. For this project we adapt traditional methods of data collection and inquiry for use in the school environment. During the late summer 2000, we conducted surveys in naturally ventilated and air-conditioned schools, polling responses from 74 students, while simultaneously measuring indoor climate variables. Air-conditioned classrooms had conditions within the comfort zone, causing occupants to report 'slightly cool' thermal sensations. The naturally ventilated classrooms were 3 °C warmer than the air-conditioned classrooms and occupants voted that conditions were also within the central three categories (surrounding neutral) of the ASHRAE thermal sensation scale-therefore equated with comfort. These 'neutral' sensations, however, do not correlate to people's preferred thermal state. Comfort responses are discussed in terms of comparisons to ASHRAE Standard 55-92 Thermal Conditions for Human Occupancy.