Inadequately sealed building envelopes can lead to significant air leakage that decreases the comfort of a building by allowing moisture, drafts, and undesired noise to enter. Air leakage may also reduce indoor air quality by permitting dust and airborne pollutants to infiltrate the building.
A building envelope constructed with proper air sealing can provide many benefits, including:
- Increased comfort: A tighter building envelope reduces the amount of unconditioned air, drafts, noise, and moisture that enter your home. Proper air sealing will also minimize temperature differences between rooms. As a result, tight envelopes can maintain a more consistent level of comfort throughout a house.
- Improved indoor air quality: A tighter building envelope reduces the infiltration of outdoor air pollutants, allergens, dust and radon as well as moisture infiltration from outdoor air in humid climates. Properly sealing the building envelope will also eliminate paths for pests to enter.
- Lower utility bills: Air leakage accounts for 25% to 40% of the energy used for heating and cooling, hampering the performance of other building systems, including HVAC, fenestration, and insulation. All building systems must perform well together to optimize the energy efficiency of a home.
- Fewer condensation problems: In hot, humid climates, moisture can enter into wall cavities through exterior cracks, resulting in mold and mildew problems that can lead to costly damage to framing and insulation. In cold climates, gaps in the interior walls allow moisture from warm indoor air to enter wall cavities and attics, which can condense on cold surfaces and lead to similar damage. Proper air sealing can significantly reduce the incidence of these problems.
Commercial Policy Options
Taken from proposals for the 2012 IECC
The building envelope shall be designed and constructed with a continuous air barrier to control air leakage into, or out of, the conditioned space. Construction documents shall identify the air barrier components for each assembly, including detailing joints, interconnects and sealing of penetrations. The opaque building envelope air barrier shall be located on the inside or, outside of, or be integral with the building envelope or any combination thereof.
BSD-104: Understanding Air Barriers | Building Science Corporation
Images courtesy of Building Energy Codes Resource Center