For a UK shop, a cassette is often the right indoor when you already have a grid ceiling and an open sales floor. Ducted is often right when the ceiling is plastered, the plan is L-shaped, or you need to serve a stock room as well as the counter. Both need an outdoor unit, an F-gas install and a load that includes the door, the lights and the people, not a domestic room chart. Survey before you pick from a photograph.
A grid over a square sales floor
A cassette drops into a grid, throws across a square floor and is a known quantity for fit-out firms. It looks like shop equipment, which is fine in most retail. It struggles if the void is shallow, if racking walls the air off, or if you need the ceiling to stay a clean plaster plane for a fitted interior.
Plaster, an L-shape, and a stock-room grille
Ducted hides the fan coil and uses grilles. It costs more to design and install, and it needs space for the unit and the distribution. In return you can put air where the customers are and leave a stock room on its own grille. That is a layout decision, made on site.
Door, glass and lights at the busy hour
People, display lighting, sun through a glazed front and a door that opens all day add up. A domestic 3.5 kW wall unit rarely holds a sales floor. The survey should state the duty at the busy hour, not at an empty Monday morning with the lights off.
- Cassette: faster in a grid, visible grille, open floor.
- Ducted: hidden fan coil, better for awkward plans and back rooms.
- Door, glass and lighting dominate the shop load.
A jet parked over the till
Staff comfort and customer comfort are not identical. A jet over the till all afternoon is a complaint. Cassette throw and duct grille direction belong on the drawing, not as an afterthought once the fascia is up. One cassette does not cool a stock room through a wall.
Building a ceiling to hide the saving
As a 2026 illustration, a single cassette in an existing grid on a small shop is the lower commercial step. Ducted runs higher because of ductwork, grilles, access and commissioning time. Making a void, out-of-hours work, and a crane or scaffold for the outdoor unit move both. If you have to build a ceiling to hide a cassette, the saving can vanish.
Landlord consent and the outdoor spot
Plan dimensions, ceiling type, photos above the grid if it is safe to take them, door position, and whether a stock room must be included. Say if you trade on Sundays or late, because install access may have to be out of hours. Landlord consent for plant is part of the same conversation. Compare the same cooling duty and the same outdoor position. The Planning Portal is the outdoor-unit check. Efficiency data must be for the quoted model, not a domestic SEER borrowed from a wall unit. Daikin is one commercial range shops get offered. GOV.UK F-gas certification applies when the work opens the refrigerant circuit, and larger charges bring extra record-keeping. Energy Saving Trust describes air-to-air heat pumps. Ask what applies to the proposed system. The reply should name kW, outdoor location and condensate.
Frequently asked questions
Is a cassette always cheaper than ducted for a shop?
In a ready grid, it is often the lower install cost. If you have to build a ceiling to hide it, the saving can vanish. Ducted costs more where it is doing more distribution.
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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.