Air Curtains vs Vestibules: Are Air Curtains a Good Alternative?

Air curtains (also known as air doors) and vestibules both serve as viable barriers to prevent air infiltration at building entrances — although by different mechanisms and with different costs.

An air curtain installed at an entryway blows a powerful air stream downwards to essential seal the entrance and prevent the infiltration of outside air and the loss of temperature in your climatized air.

A vestibule, on the other hand, is a foyer or antechamber that leads to a larger space (like an entrance hall or a lobby). The vestibule acts as a buffer and prevents sudden gusts of outside air from entering this space when someone opens the exterior doors.

Both air curtains and vestibules play an important role in maintaining consistent indoor temperatures. They also take some of the load off your heaters or air conditioning systems to create substantial energy savings.

In this post, we’ll present a comparative analysis of air curtains vs vestibules and explain which solution may be better suited for your needs.

Can air curtains replace vestibules?

As you can imagine, vestibules require additional space which can be a formidable challenge for businesses located in dense urban areas. For instance, for a retailer, every square foot of space translates to sales and revenue.

Likewise, as a restaurant owner, you could probably fit in a couple more tables in the space you’d have to carve out for a vestibule. For retail businesses, every square foot of space matters, and setting aside a large chunk of real estate just to maintain indoor temperatures is a serious waste.

Apart from eating up your floor space, a vestibule also has implications for the design of a building. It’s an additional constraint for architects who must weave in the design considerations of a vestibule into their plans.

As such, air curtains are an effective replacement for vestibules. They don’t consume floor space (they don’t create any barrier to the free flow of people or traffic), nor do they alter the architecture. They resist the entry of hot and cold air through openings in the building envelope and also act as barriers to dirt, fumes, flying insects, and wind.

Air curtains and building code compliance

The International Energy Conservation Code (IECC) — published by the International Code Council — has conventionally required buildings with over 3000 square feet of lobby/main hall to have a vestibule. This is to reduce air infiltration, heat transfer, and energy loss.

But in 2012, the International Green Construction Code (IgCC) permitted the use of an air curtain as an alternative to a vestibule. Later, in 2015, the IECC approved air curtains as effective energy conservation devices.

In 2019, however, the introduction of a new standard gave much-needed relief to engineers, architects, HVAC contractors, and building owners in the US. The American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) allowed the replacement of vestibules with air curtains for energy conservation.

Per ASHRAE Standard 90.1-2019, “Energy Standard for Buildings Except Low Rise Residential Building,” air curtains were deemed effective alternatives to vestibules in most commercial facilities. But ASHRAE 90.1 also dictates that the performance of air curtains must be tested in accordance with ANSI/AMCA 220. This is to ensure they can provide a minimum airstream velocity of 400 feet/min at the floor.

In addition, the Air Movement and Control Association International (AMCA) also sponsored the “Air Curtain Effectiveness” task force — that certifies air performance statistics of manufacturers.

All this goes to show that air curtains are not just technically sound and operationally effective, but are also compliant with building codes and regulations.

Why air curtains are fast replacing vestibules in commercial buildings

Air curtains provide fundamental advantages over vestibules that you simply can’t ignore. Seemingly small metrics like cost-effectiveness and energy efficiency can make a significant difference to your profit margins — especially in thin profit-margin industries like food service. Let’s take a closer look at the benefits of air curtains vs vestibules:

1. Air curtains are more cost-effective

Constructing a vestibule typically costs around $10,000 while you can get an air curtain for significantly less. Air curtains create significant energy savings so they actually, pay for themselves over time (typically within 18 months). Plus, they reduce the pressure on your building's HVAC system thus bringing down its maintenance costs.

The Mars ROI calculator can help you easily calculate how long it may take to recover the cost of your air curtain. Just plug in some details, like your zip code, and the calculator will automatically take into account your utility costs to paint an accurate picture.

Studies have actually proved that air curtains are more effective than vestibules at minimizing heat transfer thus, saving energy. Dr. Liangzhu Wang, Ph.D., Assistant Professor at the Department of Building, Civil, and Environmental Engineering of Concordia University, Montreal, Canada conducted a study called the “Investigation of the Impact of Building Entrance Air Curtain on Whole Building Energy Use.”

Using ANSYS Fluent for CFD simulation, he found that the whole building annual energy consumption is less with an air curtain door as opposed to the vestibule door in all climate zones. Specifically, an air curtain door can save 0.3% ~ 2.2% of the whole building annual energy usage for zone 3 ~ 8, which corresponds to 1146 kWh ~ 18986 kWh.

All to say that air curtains can reduce your carbon footprint and are in line with sustainable business practices. Also, they don’t need to keep running all the time. Air curtain switches can provide automated control of the air curtain so they turn on when someone opens the door, thus reducing the energy consumption further.

As such, air curtains can save you up to 75% in labor and material costs compared to constructing a vestibule. Plus, they’re low-maintenance and don’t require frequent servicing.

It’s also worth noting that revolving doors are essentially free-standing vestibules that are 8X more efficient than swinging doors at preventing air infiltration. But they can be expensive. You can save that cost with an air curtain.

2. Air curtains take up less space

An air curtain is simply a thin, invisible shield of air over your entryway as opposed to vestibules that are considerably larger. In fact, air curtains can help you save 50-2,000 square feet of floor space that’s typically occupied by vestibule designs.

With costs of real estate and rent skyrocketing across the country, vestibules are viewed as much less favorable than air curtains. In fact, when air curtains are a viable option, there seems to be no logical reason for simply giving up a large portion of your commercial space to construct a vestibule.

It’s easy to see why more and more businesses are opting for air curtains these days — especially given that they are now perfectly acceptable and compliant with building regulations.

3. Air curtains pave the way for better/optimized building design

With air curtains, building designers and architects are free from the constraints of leaving room for vestibules. They no longer need to alter their designs to fit in a vestibule at the entrance doors. An air curtain, on the other hand, gives ample flexibility to designers, as it has literally no architectural implications. There is also no ductwork required to install an air curtain.

Air curtains are great for retail establishments that typically get a high amount of foot traffic. In contrast, vestibules can sometimes be an obstruction that slow or impede the movement of people in and out.

Air curtains are especially useful in facilities where doors need to be kept open for prolonged periods of time. In fact, by keeping your door open at all times, air curtains help you make your store look more inviting. Open doors naturally attract more pedestrians off the street giving you more sales opportunities.

Plus, they allow the easy passage of heavy-duty goods and conveyance vehicles. In case of emergencies such as fires, air curtains allow easy evacuation because there are no physical obstructions. Doing away with a vestibule also makes your store more accessible to disabled customers or those with children, the elderly, or bulky items.

Apart from the front entrances, large back doors or other openings can also be a source of air infiltration. Air curtains can be easily installed at these openings, creating zero impact on the design or construction of your building.

Final words

Air curtains not only provide greater comfort for your employees and customers, but are also great at keeping out flies, insects, pests, pollutants, and bad odors. Commercial air curtains also find applications at cold storage facilities helping avoid wet floors and condensation and preventing accidents due to slippage.

But besides all this, they solve the most pressing challenges that come with vestibules, primarily the high costs of construction and the wastage of space. They also offer greater energy savings than vestibules and enable the free movement of goods and customers while maintaining high levels of hygiene and sanitation.

No wonder, air curtains are fast becoming the solutions of choice for business owners not just in the US, but across the world! Need help finding the right air curtain for your business? Use our interactive product builder to figure out the best solution for your facility.