Natural ventilation of dwellings is commonly applied, especially in mild and moderate climates. The disadvantage of natural ventilation is the poor control of both flow directions and flow rates within the ventilated building. To improve control, theuse of mechanical exhaust is often recommended. Though this may improve total ventilation, the ventilation of separate rooms often is insufficient still.
Air infiltration and ventilation has a profound influence on both the internal environment and on the energy needs of buildings. In most electrically heated high-rise residential buildings, in cold climates, during the peak winter conditions (below -18 deg C ambient temperature and above 15 km/hour wind velocity), the air infitration component contributes to heating load by 10 to 28 w/m2 - roughly 25 to 35% of peak heating demand. Any reduction in such uncontrolled air infiltration, without sacrificing indoor air quality, will have potential to reduce the peak heating demand.
After the oil crisis in the seventies the main aims of ventilation research changed. Many energy saving measures had been taken by the authorities, among them the reduction of infiltration heat losses. The Ministry of Building and Urban Development ordered the production and installation of better quality airtight windows, and the draughtproofing of existing window assemblies.
In Finland, there are three main topics in the field of air infiltration research: * simulation and measurement of air-leakage rates in building components and in buildings as a whole * airtightness and indoor air quality (thermal comfort) * thermal effects of air flow in building components. Goes on todiscuss aspects of air infiltration research in Finland.
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