What is an Air Barrier?
control the unintended movement of air into and out of a building
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
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
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.