“Building owners have lobbied code organizations for an alternative to vestibules because of their higher costs, waste of space, and less effectiveness compared to air curtains,” said David Johnson, director of engineering at Berner International. “The overlay helps high-performance green building advocates push through design criteria such as substituting a vestibule with an air curtain; however, it’s still up to the discretion of local code jurisdictions whether it’s accepted in a project.”

Recent proposals to the IgCC by the Air Movement and Control Association International (AMCA), Arlington Heights, Ill., helped establish air curtains as a vestibule alternative with the stipulation that they’re tested in accordance with ANSI/AMCA Standard 220-05, Laboratory Methods of Testing Air Curtains for Aerodynamics Performance Ratings.

“The IgCC is an overlay code to the base energy code,” said Amanda Hickman, manager of regulatory affairs, Intercode Inc., Delray Beach, Fla. “This means the requirements of the IECC must be met first. The IECC does not contain the same allowance that the IgCC just accepted for an air curtain alternative.”

Air curtain proponents continue to present energy efficiency data to code committees, in hopes of instituting the vestibule alternative measure into the IECC. The next meeting on the subject is scheduled for January 2013.

“The next step for the air curtain industry is to seek the same allowance that was approved by the IgCC and get it into the IECC,” said Hickman. “Then, designers will be able to use an air curtain as an alternative to a vestibule full-stop throughout the country.”

Publication date: 3/5/2012