Air curtains create an invisible air stream across an open doorway to reduce air exchange between two spaces. In this guide, we’ll cover the basics of how air curtains work, their main benefits, common applications, and the different types available.
What Is an Air Curtain?
An air curtain, also called an air door, is a ventilation device installed above or beside an open doorway. It creates a continuous stream of air across the opening, forming an invisible barrier between two spaces. Unlike a physical door, an air curtain does not block the entrance. People, carts, forklifts, and goods can pass through freely. It also helps reduce the unwanted exchange of indoor and outdoor air. This makes an air curtain system especially useful for frequently opened doors where temperature control, insect control, and indoor comfort are important.
Most air curtains are mounted horizontally above a doorway. Vertical and recessed configurations are also available depending on the doorway and building design. They are commonly used at commercial entrances, warehouses, loading docks, restaurants, and other frequently opened doorways. It is important to note that an air curtain does not create an airtight seal like a closed door. Its performance depends on proper airflow coverage, air velocity, and installation.
How Does an Air Curtain Work?
An air curtain works by drawing in surrounding air through the intake. A fan or impeller speeds up the air and pushes it through the internal air chamber. Then, the air moves towards a long discharge outlet. The outlet helps spread the airflow evenly across the full width of the doorway and creates a controlled air stream.
This continuous, high-velocity air stream helps reduce the movement of warm or cold air through an open doorway. Instead of completely blocking outdoor air, it reduces air exchange between indoor and outdoor spaces. It can also make it more difficult for flying insects, dust, fumes, and other contaminants to enter the space.
For the air curtain to work effectively, the airflow needs to cover the full width and height of the opening. It should also reach the floor or opposite side of the doorway with enough velocity. Air velocity, airflow uniformity, throw distance, and external conditions are the core factors that affect the effectiveness of air stream. This is why you should not judge air curtain performance by airflow volume alone.
Why Are Air Curtains Used?
The doorway in commercial and industrial buildings needs to open frequently due to the entry and exit of customers, employees, goods, or vehicles. Once the doorway is opened, indoor and outdoor air is exchanged. Air curtains can be used to help separate two environments without blocking an open doorway.
Reduce Heating and Cooling Loss
Every time a door opens, indoor and outdoor air can more more freely through the opening. It causes the indoor temperature becomes harder to maintain stability. This can make the HVAC system work harder to maintain a stable indoor temperature. Air curtains can help you to reduce unnecessary heating or cooling loss. They create a high-velocity air stream across the doorway to reduce air exchange. This makes it easier to maintain a stable indoor temperature and reduce the load on HVAC systems.
Improve Indoor Comfort
Due to frequently opened entrances, the temperature near entrances will fluctuate. It may create uncomfortable hot or cold drafts, especially for people standing or working close to entrances. Air curtains can keep the area around the entrance more stable and comfortable by limiting the movement of outside air. They are ideal for retail stores, restaurants, and other commercial spaces with frequent foot traffic. However, the standard air curtain cannot heat or cool the entire space by itself.
Help Control Flying Insects
A properly selected air curtain can also help make it harder for flying insects to pass through an open doorway. The high-velocity air stream can also help reduce the entry of dust, fumes, odors, and other airborne contaminants from outside. This is one reason air curtains are commonly used at restaurant entrances, warehouses, loading areas, and other entrances. However, the actual performance is impacted by airflow velocity, installation, mounting height, wind, and pressure. Therefore, we recommend you directly select an air curtain based on project requirements.
Keep Openings Accessible
An air curtain does not physically block the doorway. It can provide separation without slowing pedestrian, cart or material movement. People can walk through freely. Carts, forklifts, pallets, and goods can also continue moving in and out without waiting for a physical door to open or close. For busy entrances, loading docks, and service doors, this can help maintain a smooth traffic flow. Meanwhile, it still provides some separation between indoor and outdoor conditions.
What Are the Main Types of Air Curtains?
Air curtains come in several configurations. The main differences are airflow design, heating method, and installation style. The right type depends on the doorway, mounting conditions, comfort needs, and overall application.
By airflow design
The two common airflow designs are cross-flow and centrifugal. Cross-flow air curtains use a long tangential fan to create relatively even airflow across the unit width. They are often used for commercial entrances and applications where a slim profile and lower noise are important. Centrifugal air curtains can provide higher pressure and stronger throw. They are suitable for applications where stronger airflow or more demanding operating conditions are required.
By heating
Air curtains can be ambient or heated. Ambient models simply move room air and focus on separation. Heated air curtains can warm the air stream for greater comfort in colder environments.
By installation
Common installation options include surface-mounted, recessed, and vertical air curtains. Most air curtains are surface-mounted above the doorway. Recessed models sit inside the ceiling for a cleaner look. Vertical air curtains mount on the side of the opening and are used when overhead space is limited.
The best choice depends on the available space, doorway design, and mounting requirements. For a detailed comparison, you can see our complete guide to air curtain types.
Where Are Air Curtains Commonly Used?
Air curtains are used in many commercial and industrial settings. However, the suitability of a unit depends more on the conditions at the opening than on the industry itself.
Commercial Entrances
Air curtains are common at retail stores, supermarkets, hotels, and office entrances. These locations often have frequent foot traffic and doors that open many times throughout the day. A reliable air curtain can help maintain stable indoor conditions without blocking people.
Restaurants and Food Facilities
Restaurants, service doors, and food-processing areas often use air curtains where doors need to stay accessible during busy operations. Moreover, they can also help address the problem of flying insects.
Warehouses and Loading Docks
Large warehouse doors and loading-dock openings often have forklifts, pallets, and goods moving through them throughout the day. For these larger or more demanding openings, we recommend choosing an air curtain according to the required mounting height and operating conditions.
Cold Rooms and Freezers
Air curtains are also used at cold rooms, and freezer openings where two spaces may have a large temperature difference. A freezer air curtain helps reduce the exchange of warm and cold air every time the door opens.
The right air curtain depends on the opening size, temperature conditions, and how often the door is used. Not sure which air curtain fits your doorway? Send us your opening dimensions and application details. We’ll help you find the right air curtain for your projects.
FAQs
Do air curtains need to run continuously?
Air curtains do not usually need to run 24/7. The operating method depends on the frequency of door opening, the usage scenario and the control method. If the door opens occasionally, you can connect the air curtain with a door switch or sensor. They can help you achieve automatically start and turn off based on the door’s open or closed state. In busy locations such as retail stores, restaurants, or supermarkets, we recommend keeping the air curtain running continuously during business or operating hours.
Should an air curtain be wider than the doorway?
An air curtain should ideally cover the full width of the doorway. Its width can be the same as the door opening, or slightly larger than the door opening. If the air curtain is narrower than the doorway, there may be gaps on both sides. This allows outdoor air, dust, insects, or other contaminants to enter, reducing the effectiveness of the air barrier. For wider entrances, you can install multiple air curtains side by side to provide full coverage.
How effective are air curtains?
Air curtains can be effective when they are properly sized, installed, and operated. They create a continuous stream of high-velocity air across an open doorway. It can help reduce the exchange of indoor and outdoor air. In addition, it also helps maintain indoor temperatures while limiting the entry of dust, odors, insects, and outside air. However, air curtain’s performance depends on factors such as doorway height and width, air velocity, installation position, and outdoor wind conditions.
Can wind affect air curtain performance?
Yes. Wind can affect the performance of an air curtain. Strong crosswinds or outdoor winds can disrupt the airflow barrier formed by the air curtain. It causes the airflow to deviate or fail to stably cover the entire doorway. For windy entrances, we recommend choosing an air curtain with sufficient air velocity and airflow for the doorway height and site conditions.
Do air curtains need heating?
Air curtains do not necessarily need heating to work effectively. An unheated air curtain can still create a strong air barrier across the doorway. It also helps reduce air exchange and limit the entry of dust, insects, and outside air. The heating function is mainly used to improve comfort. A heated air curtain is more suitable for using in colder climates. It can make the entrance area feel warmer and reduce the sensation of cold drafts for customers and employees.
How to clean air curtains?
Before cleaning an air curtain, you should turn off the power first. You can use a soft cloth, soft brush, or vacuum cleaner to remove dust from the casing, air intake, and air outlet. If the air curtain has a removable filter, clean or replace it according to the manufacturer’s instructions. Regular cleaning and maintenance can help maintain airflow performance, reduce operation noise and extend service life.
Should air curtains be installed inside or outside?
Air curtains are usually installed inside the building and fixed above the doorway. Indoor installation can protect the unit from rain, dust, direct sunlight, and harsh weather conditions. It also makes cleaning and maintenance easier. In some applications, an air curtain may be installed outside, but you need to choose a unit that designed for outdoor use.
Can an air curtain replace a physical door?
No. An air curtain cannot fully replace a physical door. An air curtain creates a high-velocity air barrier across an open doorway. However, it does not provide the same physical separation as a closed door. A physical door is still important for security, sound insulation, weather protection, fire safety, and complete sealing. We recommend using air curtains together with physical doors.
What happens if an air curtain is undersized?
If an air curtain is undersized, the created air barrier cannot cover the entire doorway. A unit that is too narrow can leave gaps at the sides of the entrance. Insufficient airflow or air velocity may prevent the air stream from reaching the floor effectively. This also reduce the effects of dust prevention, insect prevention and odor isolation.
Can air curtains be used with automatic doors?
Air curtains can be used with automatic doors. The air curtain can be connected to a door switch, sensor, or automatic door control system. This helps achieve both air isolation effect and energy consumption control. It is especially useful in places with frequent traffic, such as shopping centers, hotels, hospitals, airports, and office buildings.
