Air pressure conditions in Finnish residences

Air pressure conditions in typical Finnish residences are analyzed using data from fieldmeasurements and computer simulations. Field measurements were conducted in a two-storeydetached house and in a five-storey apartment building. The effects of airtightness, ventilationrate, air leakage distributions, and outdoor environmental conditions on air pressure conditions in a detached house were simulated on a multi-zone simulation model using the IDA ICE simulation program. There is almost always a positive and negative air pressure difference across the building envelope in detached houses and in apartment buildings. During winter, in detached houses there is continuous positive air pressure at ceiling level on the top floor and negative pressure at floor level on the bottom floor. For detached houses, the design value of air pressure difference across the building envelope for the moisture convection analysis is close to 10 Pa. The control of air pressure difference in normal and leaky houses is difficult: 15 differences in ventilation airflows have only a minor influence on the air pressure difference. To control air pressure differences, the balancing of ventilation systems in airtight houses is very important.