Use of mechanical ventilation in Finnish houses

This study reports ventilation measurement and occupant questionnaire results fromnewly built 102 Finnish detached houses. The results show that ventilation units wereused constantly and the fan speed setting was changed very seldom. There was aslight tendency to use higher speed in the summer than in winter. Ventilation unitsprovide an average actual air change rate of about 0.4 ach (13 L/s,pers) both inwinter and summer which is less than the code value of 0.5 ach. Airflowmeasurements at design fan speed show that only 57% of houses comply withregulations. Low actual air change rates were caused by low fan speeds used byoccupants as 52% of houses in the winter and 47% in the summer used the lowestpossible fan speed. Correspondingly, actual supply airflow rates in bedrooms werelow, in average 4 L/s. Occupant complaints about ventilation noise correlated withnoise level in bedrooms. It is concluded that ventilation noise is an important factoraffecting the use of ventilation units. Inspection of drawings and ventilation systemsshowed that in houses not complying with ventilation regulations either ventilationunits were undersized or sound attenuation was poor.KEYWORDS: mechanical ventilation, ventilation rate, PFT, dwellings, complaints