Impact of resident behavior versus ventilation system design in indoor air quality and human health

This paper describes a study of reduced performance of mechanical exhaust systems in 42 Dutch houses after several years of operation. It also describes the effect of reduced ventilation on air quality and the perception and use of the ventilation system by residents. The guanine contents of dust samples taken from the sleeping room were determined to assess the risk of allergy.
In 93% (n=42) of the houses the reduction of the exhaust rate was more than 10% of the value demanded by Dutch building regulations that applied when the houses were built. Deterioration of the system started within 2 years. After 5 years the average reduction of the exhaust rate was 50% of the initial rate.
Interviews of the residents revealed that the systems could not be cleaned and maintained easily. Grids and fanlights in the vicinity of seats and benches were in a closed position because residents fear cold draught. To avoid noise production, residents selected the lowest speed of the exhaust fan. They did not know that minimum ventilation demands are only met at the highest speed level.