What Is an Air Curtain and How Does It Work?

You've probably walked through one without realising it. That gentle blast of air at the entrance of a supermarket, restaurant, or warehouse? That's an air curtain at work. Simple in concept but highly effective in practice, air curtains solve one of the most persistent challenges in commercial and industrial buildings: how do you keep a doorway open for people, forklifts, and goods while keeping out cold air, insects, dust, and heat? Here's everything you need to know.

What Is an Air Curtain?

An air curtain, also known as an air door, is a fan-powered device mounted above a doorway or opening that projects a continuous, high-velocity stream of air downward across the full width of the entrance. This stream acts as an invisible barrier between two environments, typically indoors and outdoors, without physically blocking the passage.

Unlike a physical door, an air curtain allows free movement of people, vehicles, and equipment through the opening while still maintaining separation between the two sides. It is used in both commercial settings like retail stores and restaurants, and industrial environments like food processing facilities, warehouses, and cold storage rooms.

How Does an Air Curtain Work?

An air curtain works by drawing air in through the top of the unit and then forcing it downward in a uniform, controlled sheet across the entire opening below. This downward airflow creates a pressure differential at the doorway that resists the movement of air, insects, and airborne particles from one side to the other.

Most units include adjustable directional vanes that allow the angle of the airstream to be fine-tuned depending on the application. Tilting the vanes slightly can improve the seal against strong cross-breezes, reduce turbulence at floor level, and help deflect insects more effectively. The stream is continuous, so people or objects moving through the doorway simply pass through the airflow without disrupting the barrier in any meaningful way.

For industrial applications such as food processing and abattoirs, air curtains must meet strict performance standards. In Australia, AQIS requirements specify that the airstream velocity must be no less than 8 metres per second, measured 900mm above the floor, across the entire opening.

Heated vs Unheated Air Curtains

There are two main types, and the right choice depends on what you primarily need the unit to do.

Heated air curtains add warmth to the airstream, making them the better choice for environments where temperature control is the main concern. A retail store entrance in winter, for example, benefits from a heated unit that prevents cold draughts from entering while also providing a secondary heat source near the door. Heated models also offer contamination control as a secondary benefit.

Unheated air curtains focus purely on creating a barrier without adding or subtracting heat. These are the preferred choice in environments where contamination control is the top priority and where adding heat could interfere with temperature-sensitive processes, such as in hospitals, commercial kitchens, laboratories, and food production areas.

What Are Air Curtains Used For?

The most common applications fall into three broad categories.

Temperature separation is the primary use in most commercial settings. An air curtain keeps conditioned air inside during both summer and winter, reducing the load on heating and cooling systems and cutting energy costs. In cold storage environments where doors open frequently for staff and equipment, air curtains can maintain internal temperatures without needing doors to close between each entry, as shown in this cold storage case study.

Insect and pest control is critical in the food industry. The downward airstream creates a moving barrier that flying insects cannot easily penetrate, helping facilities meet hygiene standards without relying on physical doors that slow down operations. Meat processing facilities in particular rely on air curtains to maintain AQIS-compliant hygiene conditions, as covered in this meat processing case study.

Dust, fume, and odour control is equally important in industrial environments. Air curtains help keep contaminants out by opposing the incoming airflow that would otherwise carry dust and fumes inside, particularly in facilities adjacent to loading docks, vehicle bays, or outdoor work areas.

Common settings include warehouses, supermarkets, restaurants, hospitals, cold storage rooms, and food processing plants.

Are Air Curtains Effective and Worth It?

Research shows that a properly selected, installed, and operated air curtain is approximately 80% effective at keeping warm air on one side and cold air on the other when a door is open. That is a meaningful result for any facility where energy efficiency matters.

From a cost perspective, air curtains are also recognised under ASHRAE Standard 90.1-2019 and the IECC building code as an equivalent alternative to a vestibule. A traditional two-door vestibule can cost between $25,000 and $50,000 to construct. A quality air curtain achieves the same outcome for a fraction of that cost, while also freeing up the entry space a vestibule would otherwise occupy.

Noise is rarely a concern for temperature-separation applications. Low-profile units designed for this purpose run quietly and produce a gentle airstream that will not disturb staff or customers. Units used for insect control move more air at higher velocity and can be louder, though mounting them externally over a rear or loading dock entrance largely removes this as a practical issue.

The Bottom Line

Air curtains are one of the more underappreciated pieces of equipment in any commercial or industrial building. They maintain comfortable temperatures, block insects and contaminants, reduce energy waste, and keep high-traffic entrances fully accessible around the clock. Choosing between a heated and unheated model comes down to whether your priority is temperature control or contamination prevention, and in many cases a good unit delivers both.