The short answer
For most UK homes, a fixed wall-mounted split system is the best balance of efficiency, low noise and cooling power, with a typical installed cost of £1,500–£3,000 per room. To cool several rooms, a multi-split (one outdoor unit, several indoor heads) is usually neater than separate systems. Portables (£300–£600) need no installation but are noisier, less efficient and only suit occasional use. The “best” choice depends on rooms, budget and whether you also want heating.
There is no single best air conditioner — the right answer depends on how many rooms you want to cool, your budget, how much noise you can tolerate and whether you want heating as well as cooling. This guide compares the main options realistically, so you can match a system type to your home rather than buy on a headline price alone.
Choosing at a glance
- Best all-round Fixed wall-mounted split system
- Several rooms Multi-split (one outdoor, several indoor)
- Occasional use Portable unit
- Split installed cost ~£1,500–£3,000 per room
- Portable cost ~£300–£600
- Look for High SEER/SCOP and quiet indoor unit
The main options
Home air conditioning comes in three broad forms, and the choice between them matters far more than the badge on the front. To go deeper on the categories, see types of air conditioning.
- Fixed split system — an indoor unit on the wall linked by refrigerant pipework to an outdoor condenser. Quiet, efficient and powerful; needs professional installation by an F-Gas-certified engineer.
- Multi-split system — one outdoor unit serving several indoor units, ideal for cooling two or more rooms without a forest of condensers outside.
- Portable unit — a free-standing box that vents hot air through a window via a hose. No installation, but noisier, less efficient and limited in capacity.
How they compare
| Type | Typical cost | Best for |
|---|---|---|
| Fixed split | ~£1,500–£3,000 installed | One room, daily use, quiet running |
| Multi-split | ~£3,000–£6,000+ installed | Several rooms from one outdoor unit |
| Portable | ~£300–£600 | Occasional use, renting, no fitting |
A fixed split wins on almost every measure except up-front cost and the need for installation. A portable wins on convenience and price but loses on noise and efficiency. For several rooms, a multi-split serving several indoor heads from one outdoor unit is usually neater than separate systems — weigh it against fitting individual splits room by room.
What actually makes one “best”
Once you have picked a type, judge specific units on the things that affect comfort and bills for years:
- Efficiency — check the SEER (cooling) and, if you want heating, the SCOP (heating) ratings and the A+++–D energy label. Higher is cheaper to run; see most energy efficient air con.
- Noise — indoor sound levels matter most in a bedroom, so check the lowest fan-speed figure on the datasheet.
- Heating too — nearly all modern splits are reversible heat pumps that heat as well as cool, so check the SCOP if you want year-round use.
- Correct sizing — the right capacity for the room beats a bigger badge; see what size do I need.
Matching the system to your home
Work back from how you live. Cooling one bedroom for sleep on hot nights? A single quiet split is ideal. Want to cool a living room and a couple of bedrooms? A multi-split keeps the outside tidy. Renting, or only need cooling a handful of days a year? A portable may be the proportionate choice despite its drawbacks. Whatever you choose, the figure on the quote should follow a proper heat-load calculation, not a guess. This page is general information and not a site-specific survey; a qualified, F-Gas-certified installer should confirm what suits your property.
Running cost and lifetime value
The cheapest unit to buy is rarely the cheapest to own. A fixed inverter split with a high efficiency rating draws far less electricity for the same cooling than an older fixed-speed unit or a portable, so over a decade of summers the difference in running cost can dwarf the gap in purchase price. A typical 2.5 kW split draws roughly 0.6–1.0 kWh per hour in use — about 15–25p per hour at a 25p/kWh unit rate — while a portable doing the same job tends to use more for less effect. When you compare options, look past the headline price to the energy grade and the SEER figure.
Lifetime value also depends on upkeep. Budget for an annual service (typically £80–£150 per unit), which keeps the system efficient and often keeps the manufacturer’s warranty valid. A well-chosen, well-installed and well-maintained split can last many years; a bargain unit that is the wrong size or poorly fitted rarely does. Choosing the right system is as much about who installs it as which box you pick, so vet the installer’s certification and survey as carefully as the unit itself.
Want a recommendation matched to your home?
A qualified installer can survey your rooms, calculate the heat load and recommend the right system type and capacity. A short survey turns a shortlist into a clear choice.
Frequently asked questions
What is the best type of air conditioning for a UK home?
For daily use in one or more rooms, a fixed wall-mounted split (or multi-split for several rooms) is usually best on efficiency, noise and cooling power. Portables suit occasional use or rented homes where fixed installation is not possible.
Is a portable air conditioner worth it?
For occasional use or where you cannot install a fixed unit, yes — at £300–£600 it needs no installation. But portables are noisier, less efficient and weaker than a fixed split, so for regular use a fixed system is usually the better long-term value.
Should I get one big unit or several smaller ones?
For separate rooms, several correctly-sized indoor units — ideally on one multi-split — cool more evenly and efficiently than a single oversized unit trying to serve everywhere. Each room should be sized to its own heat load.
Does the best air con also heat the room?
Almost all modern split systems are reversible heat pumps that heat as well as cool, often very efficiently. If year-round use matters, check the heating efficiency (SCOP) as well as the cooling rating (SEER).
Sources & further reading
- Energy Saving Trust — home cooling and air conditioning guidance
- GOV.UK / DEFRA — F-gas guidance (installation by certified engineers)
- Daikin — residential product range data (used as factual specification)
- Mitsubishi Electric — residential product range data (used as factual specification)
This guide is general information, not a site-specific survey or a substitute for a quote from an F-Gas-certified installer. Installation, servicing and refrigerant handling are legally restricted to F-Gas-certified engineers.