What is the primary purpose of an air barrier in a building?

The primary purpose of an air barrier in a building is to control air infiltration. This is essential for maintaining indoor air quality, energy efficiency, and overall comfort. By effectively managing the flow of air between the inside and outside of a building, an air barrier helps to prevent unwanted drafts, minimize the load on heating and cooling systems, and reduce energy consumption. Properly installed air barriers contribute to a more stable indoor environment by limiting the movement of unconditioned air into the habitable spaces, which can lead to significant energy savings.

While sound transmission, moisture accumulation, and thermal mass are all important factors in building performance, they do not specifically address the core function of an air barrier. Sound transmission is primarily managed through insulation and other sound-dampening materials. Moisture accumulation typically relies on vapor barriers and proper drainage systems, while thermal mass relates to a building's ability to store and release heat, which is influenced by materials rather than an air barrier's function. Thus, the focus on air infiltration underscores the crucial role of air barriers in energy-efficient building design.