Home air conditioning

Two decisions shape a home air conditioning project, and everything else follows from them: which rooms you actually want covered, and whether the system heats as well as cools. Room count sets your price band. The heating question decides your running costs, and — because the permitted development right in England is written for heat pumps and excludes units used solely for cooling — it also decides whether you need a planning application [1].

Nearly every fitted system sold in the UK today is a reversible air-to-air heat pump, so most buyers get the second answer right by default. This hub is the map: what the options actually are, what they cost, which rules apply before anything is fixed to a wall, and how to tell a surveyed quote from a guessed one.

Start here: which of these is you?

Most enquiries fall into one of four shapes, and the right first page differs for each.

• One room is unbearable and the rest of the house is fine. A bedroom that will not cool at night, a home office on the top floor, a conservatory unusable from June. A single split is almost certainly the answer. Start with the room guide, then costs.
• Two to four rooms, and you would rather not repeat the disruption. A multi-split runs several indoor units from one outdoor unit, which means one external intervention instead of three. Read the trade-off on shared operating modes before you commit.
• A renovation is already happening. This is the one moment when ducted or whole-home work is straightforward rather than invasive, because the ceilings are already open.
• The building constrains you more than the budget does. A flat with no demised outside space, a period home or a listed building. Here the siting and consent question comes first and the equipment second — sometimes the honest answer is no outdoor unit at all.

If none of those fits cleanly, the system finder turns a few details about your rooms into a preliminary steer. Weighing a plug-in unit against a fitted one is its own decision, covered in portable vs fixed.

The three system shapes

Nearly all domestic work is one of three topologies. The difference that matters is how many rooms one outdoor unit serves, and what you give up for that.

VRF appears here for completeness — it is a commercial architecture, and a house almost never needs one. For homes the real choice is single split versus multi-split, and it turns on whether you mind every room sharing a heating or cooling mode at any given moment.

Where the indoor unit goes

The indoor unit is the part you live with, and the four formats suit very different rooms.

Wall-mounted units dominate UK retrofit because they need no ceiling void and cost least to fit. Floor consoles earn their place under low windows and in rooms with no clear high wall. Ceiling cassettes and concealed ducted work need void depth you usually only get during building work.

Cooling that also heats

Most modern fitted systems are reversible air-to-air heat pumps. They move heat rather than generating it — out of your home when cooling, into it when heating — which is why they can deliver more heat energy than the electricity they consume. In practice, one discreet system cools a room in July and takes the chill off in February, usually more cheaply than direct electric heating.

This matters for more than comfort. The permitted development right is written for heat pumps, and a unit used solely for cooling falls outside it [1][2]. Specifying a reversible system is easier than applying retrospectively.

Read more on air-to-air heat pumps and systems that heat and cool, or compare the two labels in air-to-air heat pump vs air conditioning. On government support, the heat pump grant guide sets out what the Boiler Upgrade Scheme does and does not cover — air-to-air systems are the common disappointment there.

What it costs, and what moves the number

Treat those as bands for orientation, not quotations. What moves a quote within a band is rarely the equipment: it is the length and difficulty of the pipe run, whether the outdoor unit needs a bracket, a stand or a screen, how much making good is involved, and whether scaffolding or a lift is needed to reach the position. Heritage and consent work adds more again.

Capacity should be set by a room-by-room heat gain calculation — glazing, orientation, occupancy and equipment, per CIBSE Guide A methodology — not by floor area alone [5]. Tall rooms and large south-facing glazing defeat rules of thumb in both directions. A quote that arrives without that calculation has not been surveyed; it has been estimated.

Ongoing cost is modest. A 2.5kW unit typically draws 500–700W once a room is at temperature, which is pennies per hour at the unit rates the Ofgem price cap has kept typical [6]. The running costs guide sets out the arithmetic, and the cost estimator gives an indicative range for your own room list.

The rules, in short

Three regimes apply to a domestic installation in England, and all three are settled before anyone quotes properly.

• Planning. Most installations proceed under permitted development, but every condition must hold: reversible operation, volume within 1.5 m³ on a house or 0.6 m³ for a block of flats, the number allowed, nothing on a pitched roof, and the highway restrictions that apply in conservation areas and World Heritage Sites [1][2]. The 1 metre boundary rule was removed in 2025. Flats do not get the right individually, and a listed building needs consent regardless. Our planning permission guide has the full decision flow.
• Sound. Permitted development depends on an MCS 020(a) calculation showing the system within 42 dB(A) at the neighbouring assessment position, mandatory since 20 September 2025 [4]. Ask for the completed calculation for your actual property, not an assurance. See quiet units.
• Refrigerant. Since 1 January 2025, GB F-gas rules have prohibited placing new single split systems under 3kg on the market where the refrigerant's global warming potential is 750 or more, which ends new R-410A single splits. R-32 is now mainstream and R-290 is growing; existing R-410A systems remain legal to run and service [3]. Refrigerant work requires F-gas certification, and the company needs a certificate you can verify [3].

Choosing equipment, and an installer

Brand matters less than most buyers expect, and less than sizing and workmanship. Our guide to the best air conditioning brands in the UK ranks by use case rather than as a league table, and Daikin vs Mitsubishi Electric compares the two premium names directly. Landlords specifying across tenancies should start with the best brand for a rental property.

The installer decision carries more weight. How to choose an installer covers the certifications to verify and the questions that separate a firm quote from a guess, and the installation process sets out what a competent day on site actually looks like — including the vacuum test most corner- cutting skips. Where the outdoor unit goes is worth its own conversation: external unit siting.

Keeping it running

Fitted systems need periodic attention to hold both their efficiency and their warranty. How often air conditioning should be serviced covers UK intervals and where the line sits between what you can do yourself and the work that legally requires an F-gas engineer. Service costs covers what a visit should include and what it should cost.

Ready for a quote?

When you are ready, submit an enquiry. We review it individually and introduce you to one qualified installer where we can — your contact details stay private until that installer accepts the job.