What is an Air Barrier?
Air Barriers control the unintended movement of air into and out of a building enclosure.
Air barrier systems are comprised of a number of materials which are assembled together to provide a complete barrier to air leakage through the building enclosure. The building enclosure includes all six sides of the building and may included separations within a building. This system essentially “wraps” the building shell and ensures that it protects the building from the effects of air leakage. Air leakage can have detrimental effects on how a building functions and reduces the life span of a building.
A properly functioning air barrier system provides a barrier against both the air leakage and the diffusion of air caused by wind, stack and mechanical equipment pressures.
For the occupants to be comfortable, we condition the air in buildings. In summer or in cooling climates, we normally cool and dehumidify the air to a lower temperature and humidity that the exterior environment. In winter or heating climates, we normally heat and humidify the air to a higher temperature and humidity than the exterior.
When this conditioned air leaks out of a building and unconditioned air leaks into a building we must then use additional energy to then condition this air. Air leakage can result in an increased use in energy costs of up to 30-40% in heating climates and 10-15% in cooling costs.
Buildings which have a properly installed air barrier system can operate properly with a smaller HVAC system as the mechanical engineer does not have to compensate for a leaky building. In some cases, the reduction in mechanical equipment size and cost can offset the cost of the air barrier system.Air barrier systems also provide a barrier to pollutants entering either the building or the building enclosure. Water vapor, suspended particulates, dust, insects, smells, etc are all pollutants which we want to keep out of either the building in general or the building enclosure. Water vapors that leaks into the building enclose (from the inside in heating climates and from the outside in cooling climates) can condensate and forms liquid water a key ingredient to corrosion and the potential development of mold.