The relationship between humidity and indoor air quality in schools

Indoor air quality differences were investigated among five schools with and five schools without active humidity control systems. The active humidity systems provided approximately 15 cfm/person of ventilation air, while the schools without the active humidity control systems averaged less than five cfm/person. The space humidity levels in varying widely without active humidity control, and rose to unacceptable levels during summer shut-down periods. Field data and modeling showed that if the schools without active humidity control systems were operated at ventilation rates above five cfm/person, >70% relative humidity levels might occur for extended time periods. This research showed the importance humidity control and adequate ventilation in schools for contaminant control, comfort, and energy savings.