Supply and demand of indoor air qualities in dwellings

Indoor air quality (IAQ) influences the health of humans, the young and the old being generally more susceptible. In this study we examined how supply and demand of indoor air quality in dwellings are matched. On the supply-side, we evaluated ventilation systems, including natural ventilation, balanced ventilation, and adaptive systems. Two major health-related aspects are flexibility (both a secure base level and a high on-demand level) and the size of the air-exposed surface of the inlet part of the ventilation system. The indoor air quality in Dutch dwellings, as a result of ventilation system and (activity by) inhabitants, was evaluated from continuous measuring in 37 different dwellings for a whole week each during winter time. CO2 concentration, humidity class, ventilation rate and fine particle ratio (indoor versus outdoor) were used as quality parameters. On the demand-side, three population groups with different sensitivity towards air quality were identified: healthy adults (up to 49 years of age), elderly and young (aged over 49 years or under 20 years), and chronic lung sufferers. Complaint percentages in different air qualities derived from literature, and actual IAQ levels in dwellings were compared. IAQ criteria for the different population groups were derived from literature. In none of the dwellings an acceptable IAQ for the most susceptible group was present, whilst only 1 dwelling met the standards for the group of young and elderly persons. This indicates that for most of the population IAQ at home is less than optimum. Especially pollution-reservoirs should be avoided, and maintenance must be simple and effective. At present, ventilation is inadequate. Within an ageing population and an increasing incidence of airways-related diseases, ventilation facilities should be directed towards the actual needs of the persons concerned. Managing IAQ in dwellings through adaptive sensor-controlled ventilation systems may be a way to avoid health risks from indoor air for the elderly and other susceptible populations