An air curtain is a controlled stream of air across a doorway that slows the rush of outdoor air into the shop. Air conditioning cools or heats the room behind that door. They answer different problems. A high-street unit that props the door open will not hold a setpoint with a cassette alone. Many shops end up with both: a curtain at the opening, and cooling aimed at staff and customers inside. The survey should say which door position you really trade with.
A sheet of air across the opening
Warm air spills out at the head of an open door and cooler air pours in at the floor, or the reverse in winter. A curtain fan blows a sheet of air down, or sometimes across, to resist that exchange. Some curtains heat that sheet. Some are ambient. Neither one is a split indoor unit, and neither one rejects heat to a condenser by itself. Mounted badly, the curtain blows onto a thermostat or onto customers' heads and the comfort complaint gets louder. Door height, lobby depth and how often the door stands fully open all change the fan selection. That selection is a shop-door design, not a fascia upgrade.
Cooling aimed at the till, not the pavement
Staff at the till and customers in the first few metres are the people HSE's workplace temperature guidance is about. Reasonable comfort is the duty. There is no legal maximum temperature, and spending the plant's entire output on the pavement does not create comfort indoors. Aim the indoor units at the zone you occupy. Accept that the square metre in the doorway will track the street. If the door is shut most of the day and only opens for customers, a normal retail split or cassette can be sized for the room, with the curtain as a winter heat-loss tool. If the door is open all afternoon, say so before anyone quotes a closed-door kilowatt figure.
Heated curtains and a cassette that cancel out
A heated air curtain and a cooling cassette running together will happily cancel each other out. Interlocks, door switches and a sensible cooling setpoint in the mid 20s keep the plant purposeful. A building management system can do this on a larger store. A small shop can do it with a clear staff rule and a controller that is not left at 18C. The condenser for the air conditioning still needs a lawful outdoor position, a drain and an F-gas certified install. GOV.UK publishes certification for companies working on that refrigerant circuit. The curtain's electrical supply is a separate circuit for a competent electrician. Put both on one drawing so the ceiling grid is not full before the bracket arrives. Energy Saving Trust's air-to-air pages describe the cooling plant in a room it can hold. They do not describe a doorway.
Frequently asked questions
Can an air curtain replace air conditioning?
No. It reduces exchange at the door. It does not hold the sales floor at a cooling setpoint. Shops that need a cooler interior still need cooling plant.
Should the cassette be set colder if the door is open?
A lower setpoint with the door fixed open mostly buys a larger bill. Design the door treatment and aim cooling at the occupied zone. Then pick a livable setpoint.
Does the curtain need F-gas certification?
A plain air curtain has no refrigerant circuit. The split or VRF that cools the shop does. Use a certified company for that plant, and an electrician for both supplies.
What does the survey need to decide about the door?
Door position in trading hours, curtain type, indoor unit type, setpoint policy and whether summer and winter are both in scope. As a 2026 illustration, adding a commercial air curtain to a single-cassette shop is often a four-figure installed extra including VAT once power and mounting are real, and it can still be cheaper than oversizing cooling that never catches the street.
Does the curtain remove an air conditioning inspection?
No. Larger cooling systems may cross the rated-output threshold for air conditioning inspections on GOV.UK. Confirm that page for the plant you buy. The curtain does not remove the inspection question from the cooling system.
Core buying guides
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How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.