Ducted air conditioning systems
By Airva Editorial Team · Checked against published UK guidance · Updated
Ducted air conditioning hides the equipment. Instead of a unit on the wall of every room, a single concealed indoor unit sits in a ceiling void or loft and distributes air through insulated ducts to slim grilles. From inside the room you see a vent, and nothing else.
It is the most expensive and most disruptive way to cool a home, and in the right property it is the only one that satisfies. The question that decides whether it is even possible is not budget — it is whether you have somewhere to put the ductwork.
The ceiling void decides everything
A ducted system needs three things above your heads: space for the indoor unit, space for the duct runs radiating from it, and access to service the unit afterwards. That last one is forgotten with depressing regularity.
The required depth is set by the specific unit, and it is the first figure to check on the datasheet rather than a general rule. What matters is the comparison with what your house actually has:
- A generous loft above a bungalow or a top floor is the easiest case. The unit sits in the loft, ducts drop to ceiling grilles, and the work is largely out of sight.
- A suspended ceiling in part of the house — often a hallway, utility or bathroom — can carry the unit and the main duct runs, with branches into adjacent rooms.
- A boxed bulkhead built specifically to carry ducts is a legitimate answer, and it is where "concealed" starts costing you ceiling height.
- A solid-floor Victorian terrace with lath and plaster ceilings and no loft above the ground floor is where ducted schemes usually die. Not impossible, but the builder's work outgrows the air conditioning.
Where ducted genuinely wins
| Situation | Why ducted suits it |
|---|---|
| New build or major renovation | Ductwork designed in alongside everything else costs a fraction of retrofitting it. |
| Period property with protected interiors | Nothing visible on the wall of a room with cornicing or panelling. |
| Loft conversions and top floors | Void is already there, and these are the hottest rooms in the house. |
| Open-plan spaces | Multiple grilles distribute air evenly where one wall unit would leave dead pockets. |
| Whole-home coverage | One system, one condenser, rather than five wall units and a wall of pipework. |
Where a multi-split is the better buy
Be honest about what you are paying for. A ducted system delivers the same cooling as a multi-split and costs considerably more. What you are buying is invisibility.
A multi-split is the better answer when:
- You want two or three rooms, not the whole house. Ducted economics improve with coverage; at three rooms it rarely wins.
- The property is a retrofit with no useful void. The builder's work can exceed the equipment cost.
- You want room-by-room independence. A single ducted unit serving several rooms shares one air temperature unless the system is zoned, and zoning adds dampers, controls and cost.
- Budget is the binding constraint. The money is usually better spent on correct sizing and good installation than on concealment.
Zoning, and the trap of one temperature
A basic ducted system is one indoor unit blowing conditioned air into several rooms. Everything it serves gets broadly the same air, at the same time. If your south-facing bedroom and your north-facing study are on the same run, one of them will be wrong.
Zoned systems add motorised dampers and controls so rooms can be regulated separately. It is the right specification for most homes, and it is a meaningful cost. If a ducted quote does not mention zoning, ask which rooms share a zone and what happens when they disagree.
Note also that a ducted system, like any single-circuit system, cannot heat one room while cooling another. That constraint is shared with multi-splits and is worth understanding before you commit.
What ducted air conditioning costs
Whole-home ducted systems typically start around £8,000 and rise with property size and complexity. The equipment is not what drives that figure — the labour, builder's work, ceiling alterations, grilles and making good are.
Retrofit costs considerably more than the same system installed during a renovation, which is why the single most valuable piece of advice here is about timing rather than product: if you are already doing the ceilings, do the ductwork now. Adding it later means doing that work twice.
Our cost guide covers the wider picture, and running costs works out operating cost from the current Ofgem unit rate [3].
Planning and compliance
The outdoor unit is the part planning cares about, and the rules are the same as for any other system. For a house in England, a reversible unit within 1.5 m³ that meets the Class G conditions is normally permitted development [1] — note the condition that the system must not be used solely for cooling. Our planning permission guide covers it.
Ducted systems hold more refrigerant than a single split because of longer pipe runs, so it is worth having the charge recorded in kg and tCO₂e on the commissioning paperwork. Leak-check duties start at 5 tonnes of CO₂ equivalent [2], which most domestic systems sit below, but you want the figure documented either way.
Building regulations apply to the electrical work, to any structural alteration made for ducts, and to fire-stopping where ducts pass through compartment floors — which in a house with a loft conversion is a real consideration, not a formality.
Specifying a ducted system
- Room-by-room heat-load calculation, then a duct design that delivers the right airflow to each grille.
- The void depth required, checked against what the building has.
- A zoning plan, naming which rooms share a zone.
- Service access, located on the drawing.
- Grille positions and types, agreed before ceilings close up.
- Condensate route from a unit that may be in a loft — a leak here damages ceilings rather than dripping onto a floor.
Frequently asked questions
Can ducted air conditioning be retrofitted to an existing house? Sometimes. It depends entirely on available void space and access. Bungalows, top floors and houses with generous lofts are good candidates; solid-ceilinged terraces with no loft above the living space usually are not.
How much does ducted air conditioning cost in the UK? Whole-home systems typically start around £8,000 and rise with size and complexity. Retrofit costs materially more than installation during a renovation.
Is ducted better than a multi-split? Not technically — it is more discreet. Cooling performance is comparable; you are paying for concealment and even distribution. If nothing about visible units bothers you, a multi-split is usually better value.
Can different rooms be set to different temperatures? Only with a zoned system using motorised dampers. An unzoned ducted system serves its rooms with broadly the same air.
Does it need a bigger outdoor unit? Not inherently — the outdoor unit is sized on total load, as with any system. Longer duct and pipe runs do affect delivered performance, which is why the design matters.
Is it quieter than wall units? The indoor unit is remote from the room, so what you hear is air movement at the grille rather than a fan beside you. Well designed, it is very quiet; badly designed, undersized ducts generate their own noise.
Find out whether your house can take it
The void question is answered by a survey, not a brochure. Tell us about the property — age, ceilings, loft, and which rooms you want covered — and we will match you with one vetted installer who will tell you honestly whether ducted is realistic: get an installer match.