| Air Infiltration |
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“Air infiltration can account for 30% or more of a homes heating and cooling costs and contribute to problems with moisture, noise, dust and entry of pollutants, insects and rodents. Nearly 45% of this uncontrolled air infiltrates through openings in ceilings, walls and floors as well as plumbing penetrations.”
U.S. Department of Energy A better sealed, ventilated and insulated building envelope will save you money on utility bills for years to come. And by using less energy to heat and cool your home, you reduce the negative impact on the environment caused by fossil fuel use. Air Infiltration Basics: Air flows with buildings are either controlled or uncontrolled. Controlled airflow is generated by a mechanical device and is designed to help ventilate a building and/or distribute “conditioned” air throughout the house. (generally areas we want to intentionally heat and cool) Ventilation systems, bath fans, spot ventilators, kitchen range hoods, air conditioners and furnaces are typical sources of controlled air flow. Uncontrolled air flow on the other hand is any non-designed or unintended movement of air into or out of the building. This air enters the structure uncontrolled through cracks, gaps and openings – called bypasses or penetrations. This uncontrolled air flow can be caused by wind, the force of heat rising within the building (stack effect) or an uncontrolled fan. The rate of air infiltration in a home depends on many factors, the most important being the size of the bypasses in the thermal envelope and the difference in temperature between the inside and outside of the home. Warm air inside a dwelling gives rise to the stack infiltration as it tries to escape from the top of the envelope, sucking in cold air at the bottom. Wind also has a major effect on infiltration which can be at its worst on the coldest days. As a result of the widespread use of blower doors, building performance professionals are increasingly seal leak paths, often called bi-passes or penetrations in attics, basements and crawl spaces where the most significant air infiltration and ex-filtration takes place. Some of these include:
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