How to choose an air conditioning system for your home

If you want to cool one room that overheats, a single wall-mounted split is almost always the right call. For a whole home or several rooms, a multi-split sharing one outdoor unit makes more sense. If you are renting or want zero installation, a portable buys you flexibility at the cost of more noise and higher bills. And if hiding the kit matters, ducted is the tidiest option but it really needs to be designed in during a renovation.

That is the short version. The right air conditioning unit depends on how many rooms you want to cool, whether the work is going into a finished or a renovating home, how much you care about looks and noise, and whether you want the system to heat in winter too. Below we compare every type honestly, then give you a simple way to decide.

The main types of home air conditioning

There are four system types to choose from, plus one feature that cuts across all of them: reverse cycle, meaning the unit heats as well as cools.

Single split

A single split is two parts: one outdoor condensing unit and one indoor unit (usually wall-mounted), linked by copper refrigerant pipes. It cools, and if it is reverse cycle, heats one room. It is fixed permanently to an outside wall by a certified installer. Indoor units also come as floor-standing, ceiling cassette or ducted formats.

Best for: a single room that regularly overheats, such as a bedroom, home office or living room.

Multi-split

A multi-split connects several indoor units to one outdoor unit, each room controlled individually. Depending on the brand you can run up to five or six indoor units from a single condenser: Daikin and Panasonic domestic multi-splits go up to five, and Mitsubishi Electric's R32 multi-split up to six. The appeal is fewer outdoor units than fitting several separate splits, so you are not bolting a condenser onto the wall for every room.

Best for: cooling several rooms or a whole home without a separate outdoor unit per room.

Ducted / concealed

With a ducted system the indoor unit is hidden in a ceiling void or false wall, and air is delivered through discreet grilles. There is no visible indoor unit, so the aesthetics are the tidiest of any option. The catch is that it needs duct and void space, which means it is best designed in at new-build or major-renovation stage. Older properties often cannot take it without significant work.

Best for: new builds and major renovations where you want the kit out of sight and budget is not the deciding factor.

Portable / freestanding

A portable is a self-contained unit on wheels that vents hot air through a hose out of a nearby window. It needs no permanent installation, can be wheeled between rooms and stored away in winter, and many double as a dehumidifier, heater or air purifier. The trade-offs are real: portables are noisier, less efficient than splits, and warm air can leak back in through the window gap. A window-sealing kit only fits certain window types (sliding, sash or French).

Best for: renters, anyone who cannot install a fixed unit, and short-term or budget cooling.

Reverse cycle: heating as well as cooling

Reverse cycle is not a separate system type but a capability. Most modern Daikin and Panasonic domestic units, and most splits sold by UK retailers, are reverse cycle: they heat as well as cool using heat-pump technology. Heating efficiency is measured by SCOP (the seasonal heating efficiency rating), and premium splits reach A+++ with a SCOP above 5.0. Some units keep heating effectively even in hard frost. If you want one system that takes the edge off both summer and winter, choose a reverse-cycle model. This also matters for grants and planning, covered below.

Air conditioning types compared

Portable units are typically £200 to £500 to buy, with the best around £700 and good value under £300. Single splits start from around £500 unit-only. The supplied-and-fitted bands above are indicative: quotes vary widely with capacity, pipe runs, access and the number of rooms, so always compare two or more. Prices were correct at July 2026 and change frequently, so get fresh quotes before you budget.

Prices correct as of July 2026 and provided as guidance only. Installed prices are not published by manufacturers, so always get live quotes before budgeting.

How to decide: the factors that actually matter

Work through these four questions and the right system usually becomes obvious. Once you have settled on a type, our round-up of the best air conditioning units in the UK will help you shortlist specific models.

How many rooms? One hot room points to a single split. Several rooms or whole-home cooling points to a multi-split, or ducted if you are renovating. A portable only ever cools the room it stands in.

Finished home or renovating? In a finished home, splits and multi-splits are the practical choice because pipes can be run on the outside wall with minimal disruption. Ducted really wants to go in during a build or major renovation, when there is space to route the ductwork.

How much do looks and noise matter? Splits are quiet enough for bedrooms on their lowest fan speed. Ducted hides the indoor unit entirely. Portables are the most intrusive on both counts, and they tie up a window while running. If a tidy finish is a priority and you are not renovating, a discreet wall split or a ceiling cassette is the usual answer.

Do you want heating too? If yes, choose a reverse-cycle split or multi-split. As well as comfort in winter, reverse cycle is the only route to permitted development for the outdoor unit and the only type eligible for the air-to-air heat pump grant (both covered below).

If you are weighing up the two most common choices in detail, our portable vs split air conditioning comparison goes deeper on the day-to-day trade-offs.

Efficiency and running costs

Two ratings tell you how efficient a unit is. SEER measures seasonal cooling efficiency and SCOP measures seasonal heating efficiency; both feed the ErP energy label, which runs from A+++ (best) to D (worst). As a buyer's benchmark, a SEER of around 7.0 or higher is high efficiency and a SCOP of around 4.0 or higher is good. The best wall splits go well beyond this: Daikin's Perfera R32 reaches a SEER up to 8.65 and a SCOP up to 5.10, rated A+++ for both cooling and heating.

Efficiency drives your bills. The key thing to understand is that a unit's electrical input is far lower than its rated cooling output: a 3.5 kW cooling unit with a high SEER draws well under 3.5 kW of electricity. Running cost per hour is simply that electrical input (in kW) multiplied by your electricity unit rate.

Using the current Ofgem price cap of 26.11p per kWh (1 July to 30 September 2026), a unit drawing about 0.8 kW of electrical input costs roughly:

• Per hour: 0.8 kW x 26.11p = about 20.9p

• Over an 8-hour day: about £1.67

The 0.8 kW input here is illustrative. Real input power varies with the room, the load and how hard the inverter is working, so treat this as a worked example rather than a fixed bill.

Running-cost figures correct as of July 2026 and based on the Ofgem cap of 26.11p per kWh for 1 July to 30 September 2026. The cap changes quarterly, so check the current rate before budgeting.

For a fuller breakdown across system types, see our air conditioning running costs guide.

How noisy is each type?

Indoor units on a split or multi-split typically run at about 19 to 35 dB(A), dropping to the high teens or low twenties on the quietest fan speed, which is quiet enough for a bedroom. Outdoor units sit at around 45 to 60 dB(A) measured at one metre. Portables are noticeably louder because the compressor is inside the room with you. When comparing models, look for the indoor sound-pressure figure in dB(A) on the quiet or low setting, and do not confuse a product's stated dB(A) with the noise limit a planner assesses at a neighbour's window. If a portable is your only option, our guide to the quietest portable air conditioners in the UK compares models on exactly this figure.

What size unit do I need?

Capacity is rated in kW, and typical domestic sizes are 2.0, 2.5, 3.5 and 5.0 kW. A rough rule of thumb is about 0.08 to 0.15 kW of cooling per square metre, with the upper end for poorly insulated, sunny or busy rooms. Treat that as a sanity check only. The correct method is a proper heat-load calculation, because rules of thumb risk over- or under-sizing the unit, and an oversized unit cycles inefficiently while an undersized one never quite copes. A good installer will size it for you.

Installation, planning and grants

Who can install it

Any company installing or servicing a refrigerant-charged unit for you must hold F-Gas certification (F-Gas is the government regulation covering fluorinated refrigerant gases). A split has to be evacuated, leak-checked and charged with refrigerant, which only an F-Gas-qualified engineer can legally do, so DIY split installation is effectively a non-starter for homeowners. Pre-charged, sealed plug-in portables are the exception, because they need no refrigerant work. For what the job involves on the day, see our guide to how air conditioning is installed.

Planning permission

This is where many guides get it wrong. A cooling-only outdoor unit generally needs full planning permission in England, because there is no permitted-development right for a standalone condenser used solely for cooling.

A reverse-cycle unit (an air-to-air heat pump that heats as well as cools) can use the permitted-development route under Class G, subject to conditions: it must comply with the MCS 020 standard, sit within size limits, and meet siting and boundary rules, with extra restrictions for flats, listed buildings and conservation areas. The noise condition is assessed under MCS 020 rather than a single published figure. Scotland, Wales and Northern Ireland have separate regimes, so always check your local planning authority before you commit.

Grants

There is no grant for comfort cooling, and you should be wary of any claim of "free air con". The Boiler Upgrade Scheme pays £7,500 towards an air-to-water air source heat pump, which is a different technology from comfort-cooling AC.

Separately, there is a £2,500 air-to-air heat pump grant in England and Wales, effective from 28 April 2026. It is tightly conditioned: the reverse-cycle system must replace an existing fossil-fuel or electric heating system, act as the home's main heat source, and be fitted by an MCS-certified installer. A cooling unit bolted onto a home that keeps its gas boiler does not qualify, and neither do portables.

You will also need the electrics done properly. A fixed unit needs a dedicated circuit installed by a qualified electrician and notified to building control under Part P. Our planning permission guide covers the rules in full.

A cheap quote from someone without F-Gas certification is a false economy, and often an illegal one.