What is an air barrier?

What is an air barrier? Air Barriers control the unintended movement of air into and out of a building enclosure [1].

[1]ABAA, “Air Barrier Association of America (ABAA)- The center of excellence for the air barrier industry,” Air Barrier Association of America, 2011. [Online]. Available: http://www.airbarrier.org/about/index_e.php. [Accessed 26 June 2013].