Ventilation strategies and children's perception of the indoor environment in Swedish primary school classrooms

This study explored the relationship between children's subjective perception of indoor environmental quality in classrooms, measured thermal and air quality factors, and the type of ventilation. Environmental data were collected in 45 classrooms in 23 primary schools in Sweden during the heating season. Schools with three types of ventilation were recruited: natural or exhaust ventilation (category A), balanced supply-exhaust with constant air volume (category B), and balanced supply-exhaust with variable air volume or demand-controlled ventilation (category C). 796 children (8–14 years of age) answered a questionnaire about their perception of the classroom's indoor environment. Based on ten dichotomous questions, the children's overall perceptions and subjective well-being was scored (“Individual score”) from worst (0) to best (10) perception. A Perception Index (PI) was calculated as the arithmetic mean of the Individual scores from all children in a given classroom. We did not find statistically significant differences in the Individual scores or PI between the three ventilation categories. However, the PI of classrooms with ventilation category A, which also had lower ventilation rates and higher concentrations of pollutants, was noticeably lower than that in classrooms with ventilation category B or C. Correlations between the PI and most of the measured environmental parameters or the individual questions about perception were weak and not significant. The PI may be improved by including factors not considered in this study, such as those related to acoustic and lighting conditions.