Air Curtains - What is Air Curtain - Air Doors

Last Updated on November 14, 2021 by Jose Villegas Jr.

What is air curtain?

An air curtain (also known as an air door, air barrier, or air screen) is a fan-powered device that makes an air barrier invisible over the doorway, separating two distinct environments, while not restricting access for individuals or vehicles.

The energy-savings air screen cuts the costs of heating and cooling by as much as 80 percent while safeguarding the climate inside and improving the comfort of the people.

It protects the environment free of flying insects and pests, dust, airborne pollutant, smells, and scents and stops draughts. It also prevents cool or hot air entry.

The air doors consume electricity during operation, but can provide a net energy savings by reducing the heat transfer between two spaces (via mass transfer when the air mixes across the threshold).

Installed horizontal air curtain at the entranceway

How do air curtains function?

The air will be pushed through the inlet grille with filter after the power is on.
The filter shields the interior components (heat exchanger electronic components, fans, etc.) from particles and dust.
The air is then pushed into the fan housing then compressed by internal fans and accelerated through air outlet.
The air that is moving quickly enters a plenum that ensures an evenly distributed air flow across the entire width of the discharge tube.
Vanes with airfoils in the nozzle form a consistent air stream that has very little turbulent.
The air released through the nozzle produces an air stream that flows to the floor. Around 80% of the air is returned to the side that is on the intake of the air curtains and 20% of it goes to the other direction.

What are the types of air curtains?

Non-recirculating

Non-recirculating units discharge the air into the atmosphere.

Recirculating

Recirculating units gather and return air that was discharged.

Are air curtains effective?

Yes! air curtains also known as air doors or fly fans when properly installed, selected, and operated effectively work to create a barrier of the air that is blown across an opening.

This is why ASHRAE Standard 90.1-2019 and the International Energy Conservation Code (IECC) building code allows AMCA certified air doors to be applied as alternatives to vestibules.

Diagram showing no air curtain

Computational Fluid Dynamics CFD diagram-without air curtain

Diagram showing with air curtain

Computational Fluid Dynamics CFD diagram-with air curtain

The air jets from the air curtain placed on top clearly divides the cold and warm space into two different thermal zones.

UPC University air curtains studies have demonstrated that air turbulences are among the main factors that influence an air jet’s distance.

The air curtains are classified by their benefits into four categories

Commercial profit

The rise in sales is because of an “open door effect”. It is well-known to be true that, when doors opened and people are able to access the market, their wealth rises significantly.
The doorway is an open shop window, allowing shoppers to look inner workings of the business
Doors are always open, which is an invitation to customer
Access is free for people with disabilities (wheelchair) or those using baby strollers umbrellas, trolleys, and so on.
Cut the energy costs by reducing the loss of cool and hot air that escapes through doors.
Help to reduce unpleasant sensations caused by draughts
More usable space is available on entrances
Keeping indoor climate comfortable increases employee productivity and account to energy savings.

Hygienic and safe environment

Helps maintain an adequate environment
Prevent flying insects and pests
Protection against airborne dust, pollutants, fumes, and unpleasant smells

Energy conservation

Reduces energy loss in the conditioned space
Energy savings through control of air transfer
Reduces emissions of CO^₂
Reduces the energy costs of running the building
Reduce the capacity of central plants (heating/cooling)

Safety improvements

Improve visibility and reduce the risk of collisions since there’s no physical obstacle
In cold rooms, it reduces the amount of misting, dries out the doorway, and stops the formation of ice on floors
Easy evacuation via the doorway to exit in case an emergency or fire

Where to use an air curtain?

The most common places where air curtains can be put in place:

Buildings	Universities
Airports	Museums
Train stations	Theaters
Hospitals	Banks
Stores	Factories
Shopping Centers	Hotels
Restaurants	Theme & Sports Parks

Additionally, air curtains can be placed in other locations in which doors are often opened.

The use of air doors creates a seamless, invisible air barrier over any exterior opening including windows, pass-thru windows, concession windows for food trucks, dock doors, receiving doors, cold storage doors, service doors, customer entrances, and patio entrances, as well as internal separations within buildings.

The air curtain selection factors

In selecting an air curtain, these things to keep in your mind:

The installation’s height is measured by the distance from the discharge diffuser up to the floor
The door’s width
The site of the building will determine the amount of protection needed from the weather (climate, humidity, and winds)
If the building has multiple doors that are located in the same region and a different façade
If the building is comprised of several floors connected by escalators or stairs
Pressure variations between the exterior and the interior of the structure
Door characteristics: If the door is always open, it automatically opens, opens manually revolving door, etc.

Control of the air doors and regulation

Controlling the air curtains is vital to reduce unnecessary energy use by altering the efficiency of the curtains in line with the conditions at any given moment.

Do air curtains cool a room?

Air curtains are not the same with air conditioners, however, they are extremely efficient in maintaining the interior temperature by keeping cool air inside while letting warm air out in the event that the doors are opened. Since they aid in containing the air that is heated or air-conditioned, they can provide significant energy savings as well as increased comfort in commercial or industrial settings.