The Plan behind the Curtain
Retailers discover new green and IAQ uses for air curtains.
By Michael Coscarelli

Coscarelli

In the continual quest for increasing profitability by lowering construction costs, improving energy savings and reducing maintenance costs, retailers are innovating new uses for the air curtain.

 Air curtain technology isn’t new, but dozens of retail chains are finding new uses for the air curtain and they like the results. While the air curtain’s ability to separate environments within commercial cold storage facilities, trucking docks and warehouses have made it a decades-long staple in industrial applications, here’s just a few new retail applications that have come on the scene recently:

• Eliminating the need for expensive vestibules.

• Saving energy at high traffic doors.

• Improving employee air comfort at POS and near entrances.

• Increasing indoor air quality (IAQ) by eliminating the potential hazard of carbon monoxide at drive-thru window stations in quick-serve restaurants (QSR).

• Giving a store or restaurant an open-door appearance without environmental infiltration or energy losses.

• Reducing infiltration of flying insects that create unsanitary kitchen/restaurant conditions.

• Drying entranceway floors, thus eliminating slippage and reducing floor maintenance for immediate benefits.

Fortunes Coffee Roastery in Pittsburgh installed an air curtain to separate exterior and interior environments to save energy and keep employees comfortable, but a bonus benefit was drying the pavement around the threshold, which leads to drier floors and less maintenance. Photo courtesy of Berner International.

Air curtains that operate in an interior application take conditioned air from the facility and discharge it through field-adjustable (+/-20 degree) linear nozzles to produce a non-turbulent air stream that meets the floor approximately at the threshold of the door opening. Temperature differences across the opening and prevailing wind conditions cause approximately 70% to 80% of the air to return it to the space. Because the air curtain discharges at velocities generally in the range from 3,000 to 6,500 feet per minute, a strong air stream shield is created to prevent outside air, airborne contaminants and insect infiltration. To continually protect the door opening from these exterior forces, sizing and factory-engineering the air curtain for volume, velocity and uniformity is critical to its success.

Is the Air Curtain the Vestibule of Tomorrow?

Fortunes Coffee Roastery in Pittsburgh discovered sales increased 20% to 30% when the front door was propped open. However, an open door throughout Pittsburgh’s frigid winters was an energy loser and made employees cold. An air curtain installed above the door’s interior solved both problems while allowing owner Paula Scuillo to keep the door open year round. Photo courtesy of Berner International.

Some retailers are now using air curtains as a more efficient and cost-saving substitution for the conventional vestibule. For pharmacies, supermarkets, big box retailers, apparel stores and other retail formats, air curtains are hitting two birds with one stone — eliminating the need for expensive vestibules, and simultaneously reducing energy losses through doorways.

Many times, store designers run into inflexible local codes or officials that don’t allow the substitution. Such is the case with an Akron, Ohio-based architect, Timothy Londeree, R.A., David A. Levy & Associates, who has specified air curtains on dozens of commercial retail apparel projects, many times to avoid the high costs of vestibules.

While Levy customers appreciate the firm’s quest to “think outside the box” and save anywhere from $20,000 to $60,000 per project by substituting a vestibule with an air curtain in prototypical retail designs, code officials aren’t always as receptive, according to Londeree. It varies by jurisdiction, but some code officials either aren’t aware of air curtain technology or don’t allow them because they’re absent from energy codes such as the International Energy Conservation Code (IECC), which is published by the International Code Council (ICC) and adopted by more than 30 states. The IECC doesn’t disallow air curtains; there just isn’t a provision for them as vestibule substitutes — yet.

An estimated vestibule cost is anywhere from $20,000 to $60,000 while an air curtain for a single 6-foot-wide entrance/exit opening plus installation labor costs less than $6,000. Add the fact a vestibule consumes anywhere from 50 square feet at a small retail store on up to 2,000 square feet at a large home center retailer, and the advantages of air curtains appear even more impressive. Growth-minded pharmacy chains using air curtains as vestibule substitutes can save hundreds of thousands of dollars annually, which can affect bottom line construction costs. Pictured here is a Walgreens store. Photo courtesy of Berner International.

Besides construction costs, an air curtain substitution for a vestibule can also save anywhere from 200 to 500 square feet of space that can be used for merchandising.

New Study Might Help Change Codes

While there’s no doubt about the savings in construction costs and square footage, a new study proved what a lot of consulting engineers had assumed all along — that air curtains actually save energy versus vestibules. Produced last year by an air curtain manufacturer with second-party validation from a Charlottesville, Virginia-based research/validation consultant, Blue Ridge Numerics, the study has become a credible document that architects and consulting engineers are now using as a reference with code officials. The newly released 3-month-long research study has certified results from proven computational fluid dynamics (CFD) analysis. When compared to conventional automatic two-door vestibules, the study’s results overwhelmingly confirm that an air curtain/automatic door entrance combination is up to 10% more energy efficient in environmental separation performance. The study’s results can be referenced at www.berner.com.

The IECC’s Section 103.1 (Alternate Materials–Method of Construction, Design or Insulating System) does specify that alternatives to the code can be used based on a local code official’s discretion, according to Vickie Lovell, president of Intercode Inc., a Delray Beach, Florida-based building code consulting firm. Specifically, it reads: “This code is unintended to prevent the use of material, method of construction, design or insulating system not specifically prescribed herein; it provides that such construction, design or insulating system has been approved by the code official as meaning the intent of this code.”

This Drive Thru Unit (DTU) air curtain was developed in response to quick-serve restaurants that needed to prevent the infiltration of insects, vehicle emissions and wintertime air. Photo courtesy of Berner International.

Londeree has referred several code officials to the research study when questions arise about the viability of air curtains versus vestibules. Some code officials change their minds, while others remain steadfast behind the current IECC language. “Just because one code official approves or disapproves of an air curtain as an alternative method, it doesn’t mean the next code official will agree with that precedent or reach the same conclusion,” says Lovell.

New Uses for Air Curtains

Many convenience stores and restaurants aren’t newcomers to air curtains because they’ve used the technology on back-end operations for years, mainly to improve kitchen sanitation by eliminating flying insect infiltration. Putting air curtains on front-end operations to save energy is a new twist, however. Convenience store chains — such as Des Moines, Iowa-based Kum and Go — are using air curtains on front doors to save energy and improve employee air comfort during extreme winter temperatures while simultaneously eliminating flying insect infiltration.

It’s the energy-saving possibility of air curtains that appear to supplement many retailers’ green missions. In addition to high-efficiency lighting, 13-SEER HVAC and other green elements, the air curtain in its new Johnston, Iowa, fuel/c-store location could help the 430-store chain successfully register its first Leadership in Energy & Environmental Design (LEED) store with the U.S. Green Building Council (USGBC), based in Washington, D.C. (The store’s LEED application status was still undetermined by press time.)

At an Arby’s restaurant in Struthers, Ohio, a drive-thru window air curtain has been successfully beta tested to stop the infiltration of harmful idling vehicle emissions, flying insects, and extreme temperatures. Specially-designed drive-thru window air curtains are relatively a new concept, but they could be instrumental in protecting employees from vehicle emission inhalation. Better employee health could possibly help reduce the restaurant industry’s skyrocketing turnover rate, which the National Restaurant Association (NRA) estimates as 145%.

In theory, one end of a vestibule doorway should open after the other end closes; however, high traffic patterns typically keep both ends open simultaneously and allow free flow of air into the building. An air curtain positioned on the interior wall above the inside doors would eliminate air infiltration. Also, the interior door wouldn’t be needed. Air curtains combined with an automatic door has been proven to save more energy than a conventional vestibule. Photo courtesy of Berner International.

The U.S. Labor Department’s Occupational Safety & Health Administration (OSHA) has recently alerted QSRs that inhalation of vehicle emissions carries a potential hazard such as carbon monoxide (CO) poisoning (www.osha.gov). Combined with the fact that an increasing majority of restaurant business is transacted at drive-thru windows, unchecked vehicle emission challenges will grow for QSR’s.

The drive-thru air curtain stops more than vehicle emissions, however. Because it separates the exterior/indoor environments at the window threshold, drive-thru operators, as well as other employees working nearby are not subjected to sub-freezing temperatures during Ohio’s cold winters. This adds employee indoor air comfort as well as safety and energy savings factors to the drive-thru air curtain.

Employee air comfort was also a major concern at Fortunes Coffee Roastery in Pittsburgh’s famous Strip District after owner Paula Sciullo discovered foot traffic and sales jumped 20% to 30% when the front door remains open. Passersby see the coffee retail store as more inviting when the doors are open; however, sub-freezing winter temperature typically left employees chilled in the small 1,200-square-foot store. After installing a 72-inch-wide air curtain above the front door, exterior/interior environments were separated. Sciullo gained more sales, employees stayed warmer, and energy losses were minimized.

Other retailers have used this strategy as well. At a north side of Chicago location, Whole Foods uses an air curtain to separate environments when a wide, former garage doorway remains open during business hours. The garage doorway was retained in the store design when the former factory was converted to a unique, industrial-style urban store. Leaving the doorway open establishes an inviting auxiliary doorway for approaching customers.

It’s expected that even more uses for the air curtain will be developed in the future as retailers creatively see additional opportunities to save energy, increase IAQ and improve overall operations.

Michael Coscarelli has been with New Castle, Pennsylvania-based Berner International for 26 years. He is currently the company’s national sales manager. Coscarelli has also been an advocate of furthering the standards and exposure of air curtains and has served on the sales/marketing committee of the Air Movement and Control Association (AMCA), based in Arlington Heights, Illinois, for 5 years