Ventilation in 102 Finnish single-family houses

This study reports generally low actual air change rates in Finnish houses. Average air change rates in winter were 0.3 ach (11 l/s,pers) in natural, 0.34 ach (10 l/s,pers) in mechanical exhaust and 0.41 ach (13 l/s,pers) in mechanical supply and exhaust ventilation. The prevalence of indoor climate related complaints was lowest within an air change range of 0.3...0.5 ach. At lower air change the prevalence of odors and at higher air change the prevalence of draft and dry air was significantly higher. Ventilation units were used at low speeds (1/4 or 2/4 in 93% of houses in winter) which was the reason for low supply airflow rates (2.1 l/s,pers) as well as low noise levels (22 dB(A)) in bedrooms. In general, larger, in some cases even oversized ventilation units resulted as higher air change rate at lower noise level.