Building Codes: What You Need to Know about Vestibules and Air Curtains

[This blog was originally published on August 21, 2018 and was updated on April 24, 2020]

What is an air curtain?

An air door or air curtain is a device used to prevent air or contaminants from moving from one open space to another. The most common use is a downward-facing blower fan mounted over an entrance to a building, or an opening between two spaces conditioned at different temperatures.

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) defines an air door as follows: “In its simplest application, an air curtain is a continuous broad stream of air circulated across a doorway of a conditioned space. It reduces penetration of insects and unconditioned air into a conditioned space by forcing an air stream over the entire entrance. The air stream layer moves with a velocity and angle such that any air that tries to penetrate the curtain is entrained. Air curtain effectiveness in preventing infiltration through an entrance generally ranges from 60 to 80%”. 

The Air Movement and Control Association (AMCA) defines an air curtain as: “A directionally-controlled airstream, moving across the entire height and width of an opening, which reduces the infiltration or transfer of air from one side of the opening to the other and/or inhibits flying insects, dust or debris from passing through”. In North America, the more commonly used term for an air door is “air curtain”.
(Credit: Wikipedia)

What is a Vestibule?

A vestibule, also known as an arctic entry, is an anteroom (antechamber) or small foyer leading into a larger space, such as a lobby, entrance hall, passage, etc., for the purpose of waiting, withholding the larger space view, reducing heat loss, providing space for outwear, etc. The term applies to structures in both modern and historical architecture since ancient times. In modern architecture, commercial vestibule typically refers to a small room next to the outer door and connecting it with the interior of the building. In ancient Roman architecture, vestibule (Latin: vestibulum) referred to a partially enclosed area between the interior of the house and the street.
(Credit: Wikipedia)

Is a vestibule required by code?

We often get asked whether commercial vestibules are required by code or not. To answer this question in short: Vestibules are required by code but if you can’t have a vestibule then you can use an air curtain as an alternative. Want to learn more about this requirement, read below on or click on this link.

What is the IECC (The International Energy Conservation Code)?

The International Energy Conservation Code (IECC) was established in 2000 and institutes a range of energy efficiency requirements for both residential and commercial buildings. In relation to air curtain technology, the most relevant part of the code is the vestibule requirement. In the past, the IECC code has required commercial building designers to include vestibule entrances on the primary entrance doors to large open spaces. Specifically, the requirement states that primary entrance doors to spaces that are 3,000 square feet or larger must include vestibules. In other words, if the main lobby of a building is 3,500 square feet in size, then the primary entrance to that space must include a vestibule.

This requirement puts an obvious burden on building designers, project developers, and building owners alike. For one thing, commercial vestibules take up much space on their own and eat up valuable real estate in a building. Even small entrance vestibules or lobby vestibule take up valuable floor space in a mostly non-functional way. Vestibules also add extra costs to the building project or force expensive and time-consuming redesigns to avoid the IECC rule.

Vestibule Cost – Vestibules themselves can cost $15,000 – $ 20,000, meanwhile, an unheated air curtain can range from $900 – $1,200, and a heated air curtain can range from $2,000 – $2,500.

What is the IGCC (International Green Construction Code)

The International Green Construction Code (IGCC) regulates the construction of new and existing commercial buildings. The release of Public Version 1.0 was announced by the International Code Council on March 11, 2010. The IGCC was established to aid in the construction of sustainable buildings in the business and residential sectors.

Why the Vestibule Requirement Exists

Before we get to the air curtain part of this conversation, let’s talk a little bit about why the IECC requirement includes a vestibule requirement in the first place. After all, vestibules are not—and have never been—an efficient use of space. Why was this building design strategy ever utilized, let alone required by an international building code?

According to the United States Department of Energy, the intention behind the vestibule requirement is “to reduce infiltration of air into a space.” By cutting down on infiltration, vestibules help limit heat transfer, reduce energy usage, and provide greater creature comfort to occupants or guests just inside the entrance.

IECC / ASHRAE and Air Curtains

Of course, vestibules have been rendered mostly obsolete by air curtains. Air curtains can achieve the same benefits as vestibules—the energy conservation, the creature comfort, the limited infiltration of fumes or contaminants—without taking up precious ground space or adding tens of thousands of dollars to the construction bill. By simply installing air curtains on their primary entranceways, commercial building designers can do more with less.

There are stipulations, of course. The IECC / ASHRAE only recognizes air curtains as meeting the vestibule requirements if they meet the following criteria:

• They have been tested and found to meet ANSI/AMCA Standard 220
• They are installed in accordance with all manufacturer instructions
• They have an air stream velocity of 2 meters per second, directed at the floor
• They have manual/automatic controls that allow the air curtain to operate when the door opens
• The air curtain controls are compliant with Section C408.2.3 of the IECC / ASHRAE Standard 90.1-2019

The good news is that air curtain manufacturers are familiar with these requirements and have taken steps to comply with them. For instance, Berner & Mars are two of the biggest brand names in the air curtain market, offers air curtains that have been “certified” to meet the IECC building code /ASHRAE Standard 90.1-2019. Most Berner & Mars air curtains have been carefully tested and certified per the ANSI/AMCA Standard 220. Commercial building owners who are required to comply with the IECC /ASHRAE vestibule rule should make sure they are purchasing air curtain systems that include this certification. If you are worried about air curtains being loud, manufacturers have low noise units available for the quietest of applications.

Air Door Distributors supplies both Mars & Berner AMCA certified air curtains to meet ASHRAE Standard 90.1-2019 and the IECC Building Code.

Here is a list of Berner & Mars series that meet building codes (ASHRAE Standard 90.1-2019, IECC, IgCC) for main entrances with AMCA certification:

BERNER Air Doors:

Most Common for Vestibule Use
Commercial High Performance 10 Series (CHD10): Unheated, Electric Heated, Steam, Hot Water
Architectural High Performance 10 Series (AHD10): Unheated, Electric Heated, Steam, Hot Water
Architectural Elite 8 Series (AED08): Unheated, Electric Heated
Architectural Recessed 12 Series (ARD12): Unheated, Electric Heated, Steam, Hot Water
Architectural Recessed 16 Series (ARC16): Unheated

MARS Air Doors:

Most Common for Vestibule Use
Standard 2 Series (STD2): Unheated
High Velocity 2 Series (HV2): Unheated
Phantom 10 Series (PH10): Unheated
Phantom 12 Series (PH12): Unheated

To make it easy to know if a model is viable for energy code vestibule exceptions, look for the AMCA seal on Berner & Mars spec sheets. 

Click here to find the status the energy code adoption by state

In addition to product innovation, Berner & Mars have been instrumental in the drive to achieve greater recognition of the air curtain, a.k.a. air door, as an important part of any building’s design.  Part of that drive has been to research and promote third-party studies on the efficacy and benefits of air curtains.  This research has led to air curtains being included as an exception to vestibules in ASHRAE Standard 90.1-2019, ASHRAE Standard 189.1, the IECC (International Energy Conservation Code) and the IgCC (International Green Construction Code) building codes.

ASHRAE Standard 90.1 Update Approved!

Effective Fall of 2019, ASHRAE Standard 90.1, “Energy Standard for Buildings Except Low Rise Residential Buildings,” allows air curtains tested in accordance with ANSI/AMCA Standard 220 as an exception to vestibules

ASHRAE Standard 90.1,Section 5.4.3.3 Vestibules and Revolving Doors  states:

Vestibules and revolving doors shall be installed in accordance with this section. The new list of exceptions include air curtains complying with mandatory provisions and can be found in Section 10.4.5:

“Air curtain units shall be tested in accordance with ANSI/AMCA 220 or ISO 27327-1 and installed and commissioned in accordance with the manufacturer’s instructions to ensure proper operation and shall have a jet velocity of not less than 6.6 feet per second (2.0 m/s) at 6.0 in (15 cm) above the floor and direction not less than 20 degrees toward the opening. Automatic controls shall be provided that will operate the air curtain with the opening and closing of the door.”

NOTE: 2 m/s is equivalent to 400 ft/min

Code Change Approved!

Code change proposal CE192-13, toward the 2015 IECC (International Energy Conservation Code) was approved at the IECC (Group B) Committee Action Hearings in Atlantic City, N.J. The code change adds air curtains as an exception to a vestibule in the section C402.4.7 Vestibules. The new code reads:

Exceptions: Vestibules are not required for the following: Item 6. Doors that have an air curtain with a minimum velocity of 2 m/s at the floor, have been tested in accordance with ANSI/AMCA 220 and installed in accordance with manufacturer’s instructions. Manual or automatic controls shall be provided that will operate the air curtain with the opening and closing of the door. Air curtains and their controls shall comply with Section C408.2.3.

Code Change Approved!

The 2012 IgCC (International Green Construction Code) states,

“Where a building entrance is required to be protected with a vestibule in accordance with the International Energy Conservation Code, an air curtain tested in accordance with ANSI/AMCA 220 is permitted to be used as an alternative to separate conditioned space from the exterior.”
See page 37, Section 605.1.2.3 Air Curtains in the 2012 IgCC

Third-Party Certifications

Berner & Mars use industry-accepted best practices and third-party certifications to verify that what we build is safe to use and does what we say it does.  Some product certifications are required as part of being in compliance with various building codes and health codes.

AMCA CERTIFIED AIR PERFORMANCE

• AMCA (Air Movement and Control Association) International, backed by almost 80 years of experience, is the world’s leading authority in the development of the science and art of engineering as relates to air movement and air control devices.  AMCA standards are referenced by building codes all over the world.
• Berner & Mars Air Curtains are tested in accordance with AMCA Standard 220 – Test Methods for Air Curtain Units – assuring customers that their unit will perform as stated. A unit that has not been tested and certified in accordance with AMCA Standard 220 may not be reliable or meet the performance claimed by the manufacturer. Accurate information helps you make the right decision.
• The AMCA seal on a product’s data sheet means that AMCA has independently tested the product and certifies the published performance data for that product is accurate.
• For AMCA’s directory of certified products, click here.

UL CERTIFICATION

• UL is a nationally recognized testing laboratory. UL Standards for Safety help insure public safety and confidence in product. Millions of products and their components are tested to UL’s rigorous safety standards. Berner  & Mars understand the importance of UL certified products.

C-UL CERTIFICATION

• A UL certification, the C-UL (Canada – Underwriters Laboratories, Inc.) mark appears on products for the Canadian market. The products with this type of mark have been evaluated to Canadian safety requirements, which may be somewhat different from U.S. safety requirements

NSF/EPH CERTIFICATION

• Berner & Mars manufacture Air Curtains / Air Doors with EPH certification tested to ANSI/NSF Standard 37 for flying insect control for many food service applications. The presence of the UL/EPH Mark on food service equipment means that the equipment has been evaluated, tested, and certified by UL as meeting international commercial food equipment standards. Berner air curtains that meet ANSI/NSF Standard 37 help keep your food establishment free of insects and are noted as, “EPH Listed per NSF 37.”
• NSF International is an independent, not-for-profit organization dedicated to public health safety and protection of the environment.
• NSF/ANSI Standard 37 is the certification for air curtains for entrance ways in food and food service establishments, e.g., service and customer entries, service windows, cooler and cold storage entries.
• Many health departments, and some building codes, around the country require an EPH Listed per NSF 37 air curtain and/or some other chemical-free insect deterrent as part of being in compliance with their heath and safety standards.

EPH CERTIFICATION

• A UL certification, the UL EPH (Environmental & Public Health) mark appears on products that have been evaluated to Environmental and Public Health Standards. Berner & Mars manufacture many products that are UL EPH certified to NSF/ANSI standard 37.

FDA RECOMMENDATIONS

• A part of the United States Department of Health and Human Services (HHS), the FDA (United States Food and Drug Administration) is one of the nation’s oldest and most respected consumer protection agencies. Stated most simply, FDA’s mission is to promote and protect the public health by helping safe and effective products reach the market in a timely way, to monitor products for continued safety after they are in use, and to help the public get the accurate, science-based information needed to improve health.
• The FDA is the regulatory body of the United States Department of Health and Human Services.
• In the 2000 Food Establishment Plan Review Guide, the FDA recommends controlled air currents (which is what an air curtain provides) for insect control at all openings, as well as specifically recommends air curtains for loading docks and delivery doors.
• In Chapter 6 of the 2001 Food Code put out by the FDA, Section 6-202.15 Outer Openings, Protected, properly designed and installed air curtains are specified as a method to protect openings of food establishments against the entry of flying insects.

USDA RECOMMENDATIONS

• The USDA’s, “Sanitation Performance Standards Compliance Guide,” recommends air curtains for protection against insects and rodents for windows and doors of food establishments.

DOE ENERGY CONSUMPTION STANDARDS – WALK-IN COOLERS / FREEZERS

• The DOE has issued energy consumption standards for certain walk-in cooler / walk-in freezers based on the Energy Independence and Security Act of 2007 (HR 6, Section 312).  By protecting the interior temperature of the walk-in when the door is open, research has shown that properly sized and installed air curtains are effective at reducing the number of run times for the compressor, thus reducing energy consumption.

Other Sources

ASHRAE HANDBOOKS

• Air curtains can be found in the following ASHRAE Handbooks: “HVAC Applications,” “HVAC Systems and Equipment,” and “Fundamentals.”

At Air Door Distributors, we can help you find certified air door products from trustworthy brands, including Berner. To find the right vestibule alternative for your building, contact us today.