Good news for building owners, engineers/architects, and HVAC contractors who can now save energy, construction costs, and space in commercial facilities with this approved code addition.
Doorway air curtains were approved as alternatives to vestibules on most commercial building entries in the upcoming ASHRAE Standard 90.1-2019 Energy Standard for Buildings Except Low Rise Residential Buildings.
The professional association’s approved addition requires that the air curtain performance be tested in accordance with ANSI/AMCA Standard 220 to ensure it provides a minimum of 400-ft/min. airstream velocity at the floor.
Waive Expense Of Vestibules
This is good news for retail, restaurants, healthcare, hotels, office, and other facility owners, because they can now opt to forego the expense of vestibules in new construction, or repurpose significant square footage for more productive uses by retrofitting existing vestibules.
Consulting engineers and architects, who previously were hesitant to replace vestibules with air curtains due to inconsistent code language, now have the support of ASHRAE Standard 90.1-2019 which will be published soon.
Air Curtains On Demand
HVAC contractors will see a spike in air curtain installations to accommodate facilities looking to prevent energy loss through their main entries and meet building codes.
Air curtains also protect against the infiltration of outdoor air, fumes, flying insects, wind, and dust through open doorways, and contribute to occupant air comfort.
AMCA’s Sponsorship
The addition’s Air Curtain Effectiveness task force was sponsored by AMCA (Air Movement and Control Association–International), an Arlington Heights, Ill.-based trade association dedicated to certifying manufacturers’ air performance statistics.
“This is the most significant recognition of air curtains as an effective energy conservation device since the International Energy Conservation Code (IECC) approved air curtains as vestibule substitutes in 2015,” said David Johnson, President of AMCA, and Director of Engineering for Air Curtain manufacturer, Berner International, New Castle, Pa.
Research And Performance
ASHRAE’s mechanical, building envelope, and other subcommittees required additional research of real-world air curtain situations Inclusion in ASHRAE Standard 90.1 required more than eight years of air curtain research and presentations.
The IECC code and the high-performance overlay code, the International Green Construction Code (IgCC), helped initiate the path to Standard 90.1 acceptance by allowing AMCA-certified air curtains as substitutes for vestibules.
However, ASHRAE’s mechanical, building envelope, and other subcommittees required additional research of real-world air curtain situations such as wind loads and building pressure differentials on an annual national-weighted average basis.
Air Curtains Equally Effective Than Vestibules
Subsequently, the subcommittees accepted AMCA’s commissioned research represented by three third-party lab studies by Montreal-based Concordia University professor, Dr. Liangzhu Wang.
All three studies proved air curtains that maintained a minimum of 400 ft/min. airstream at the floor (as per ANSI/AMCA Standard 220), were equally effective or better than vestibules in buildings 3,000-square-feet and larger.
Testing Air Curtains
Decades ago, two-door vestibules were code-mandated to save building energy. Theoretically, they created an airlock as one door would open and close before the second door opened.
However, the emergence of automatic door opening sensor requirements, smaller space-saving dimensions, and other infringements on vestibule effectiveness, helped make air curtains an attractive energy-saving alternative.
Saving Energy Usage
On average, air curtain-protected doorways were proven to save total building energy usage by a factor of 0.3-2.2% moreover that of vestibules, according to Wang’s studies.
This illustrates they’re equal or more effective at separating outdoor and indoor environments regardless of the door opening styles or cycles.
