Perceived air quality, temperature, air movement, natural ventilated spaces
Perceived air quality is an important aspect in current guidelines and standards for indoor environment. It represents occupants’ real feeling about indoor air and affected by almost all environmental parameters, such as the temperature, the relative humidity, the air movement, and et al. Studies were conducted mainly in controlled climate chambers or air-conditioned spaces, rarely in natural ventilated spaces. In this paper, the effects of temperature and air movement on perceived air quality in natural ventilated classrooms are investigated. The indoor environmental parameters in 7 classrooms for 35 lessons are continuously measured and the students in class are asked to report their perception on the temperature, air movement, and the air quality of classrooms by filling questionnaires at once after a lesson. The number of received validated questionnaires is 992. The correlation analysis is used to investigate the effects of temperature and air movement on the perceived air quality. Results show that in natural ventilation classrooms, which are warm at temperature and moderate at humidity with an air speed lower than 0.1m/s, it is the thermal sensation rather than the temperature, enthalpy, thermal acceptability, or CO2 concentration that affects the perception of occupants for air quality. The perception for air movement influences the air quality acceptability. Increasing air movement increases the air quality acceptability. Besides, it is found that the preference of air movement is related to the air quality acceptability. When participants feel that the air movement is just suitable, the acceptability of air quality reaches the highest. When participants feel the air movement need to be adjusted, the air quality acceptability decreases.