Development and Adoption of Air Leakage in Building Codes
All Codes are Local
Sponsored by Air Barrier Association of America | Presented by Theresa A. Weston
Live Webinar Airing on October 16, 2025 at 11:00 AM ET
Model energy efficiency codes (ASHRAE 90.1 & Internation Energy Efficiency Code (IECC)) are under continuous maintenance and publish an updated edition every three years. The energy code, however, does not become a regulation until it is adopted by a state or jurisdiction. Therefore the timeline for updating varies by individual jurisdiction. Further, the adopted code must than be enforced by local authorities. This presentation will discuss the development of air leakage requirements in the model energy codes for commercial buildings. It will then describe the status of adoption of model codes by the states. Finally, the implications for enforcement through whole building airtightness testing of the adopted code will be discussed.
Photo courtesy of Holt Weston Consultancy, LLC
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Dr. Theresa A. Weston is a building science research professional specializing in the durability and energy efficiency of buildings. She started The Holt Weston Consultancy in November 2020. Prior to starting her company, Dr. Weston was a DuPont Laureate with Dupont Safety and Construction where she was active in product and market development. She is an inventor on four U. S. patents. In addition to building science consulting, Dr. Weston is an ASHRAE Distinguished Lecturer. She received her Bachelor of Science degree in Chemical Engineering from the Massachusetts Institute of Technology, and Masters and PhD degrees in Chemical Engineering, both from the California Institute of Technology. Dr. Weston is active in industry standard and code development. At ASHRAE, she has served on the Technical Activities Committee, the Standards Committee and as the Chair of the Residential Buildings Committee, as well as serving on a number of Technical and Standards Project Committees. As chair of ASHRAE 90.2 ANSI/ASHRAE/IES Standard 90.2-2018, Energy-Efficient Design of Low-Rise Residential Buildings, Dr. Weston led the committee to transform the standard to a leadership standard. At ASTM, she has served as the chair of E06.41 “Performance of Buildings Sub-Committee on Air Leakage and Ventilation”. She has been awarded the DuPont Lavoisier Medal for Lifetime Technical Achievement, the ASHRAE Distinguished Service, Exceptional Service and Residential Service Awards, the Wagdy Anis Award from the Air Barrier Association of America, and the E. George Stern Award of Excellence from ASTM Committee E06. |
The Air Barrier Association of America (ABAA) is a national, not-for-profit trade association comprising a broad cross section of stakeholders in the building enclosure industry. Their membership, which is over 650 member companies, includes manufacturers, architects, engineers, trade contractors, researchers, testing & audit agencies, consultants and building owners. ABAA is the national voice of the air barrier industry and the number one resource for anything to do with air and moisture barriers.
Originally published in Building Enclosure
Originally published in September 2025
LEARNING OBJECTIVES
- Recognize how code regulations for air leakage control have evolved in the model codes (ASHRAE 90.1 & IECC).
- Cover the status of state adoption of model codes.
- Recognize through examples, how air leakage control regulations are specific to climate zones and, therefore, to state requirements.
- Cover required air barrier verification included in code enforcement, including when whole building air barrier airtightness testing and/or dwelling unit testing is required.
