Room Airflow Rates in Finnish Houses

Airflow rates were measured in one hundred and two newly built single-family houses during 2002-2004. Of the measured houses, 10 % used natural ventilation, 28 % used mechanical exhaust and 61 % used mechanical supply and exhaust. Exhaust airflow rates were measured during the summer period from terminals. Supply airflow rates and sound pressure levels were measured in master bedrooms. During a 2-3 week period in winter, air change rates were measured with a passive tracer gas technique to determine the overall air change rate.
An average actual air change rate in the summer period was 0,40 1/h in houses with mechanical supply and exhaust ventilation and 0,37 1/h in houses with mechanical exhaust ventilation. Winter period values were respectively 0,41 1/h, 0,34 1/h and 0,3 1/h in naturally ventilated houses. All these values are below the code value of 0,5 1/h. Similarly, the average supply airflow rates in bedrooms were lower than the recommended value in the building code. Both exhaust and supply airflow rates will be reported.
Actual air change rates, room airflow rates together with sound pressure levels compared to airflow rates at the design speed of the ventilation units show possible improvements needed in the ventilation of houses.