A study released last month by the National Institute of Standards and Technology (NIST), “Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Energy Use,” confirms that continuous air barrier systems can reduce air leakage by up to 83% and energy consumption by up to 40%. The report states that:
“Despite common assumptions that envelope air leakage is not significant in office and other commercial buildings, measurements have shown that these buildings are subject to larger infiltration rates than commonly believed. Infiltration in commercial buildings can have many negative consequences, including reduced thermal comfort, interference with the proper operation of mechanical ventilation systems, degraded indoor air quality, moisture damage of building envelope components, and increased energy consumption.”
The study was conducted by Steven J. Emmerich (Building and Fire Research Laboratory, NIST), Timothy P. McDowell (TESS Inc.), and Wagdy Anis (Shepley Bulfinch Richardson and Abbott). It evaluated the energy savings of an effective air barrier requirement for non-residential buildings in five cities representing different climate zones (Miami, Phoenix, St. Louis, Bismarck, and Minneapolis).
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 90.1 Envelope Subcommittee is looking to update the building air leakage requirements in the standard to include a continuous air barrier system. The NIST report was prepared in part to show that committee the potential energy savings and cost effectiveness of an air barrier requirement.
Some states mandate thermal air barrier systems as part of their Commercial Energy Code, and 29 other states include similar mandates in their provisional Energy Codes.
For more on this report, or to download a PDF of the report, visit the NIST website at www.nist.gov/public_affairs/techbeat/tb2005_1007.htm.