Portable vs split air conditioning — which should I choose?
If you want cooling today with no installation, choose a portable unit: it plugs into a normal socket, vents warm air out of a window through a hose, and can be moved from room to room. If you want quieter, more efficient cooling that stays put, choose a fixed split system — but it must be installed by an F-Gas-certified professional and is a bigger commitment. Most UK households trying air conditioning for the first time start with a portable.
How does a portable air conditioner work?
A portable air conditioner is a single self-contained unit on castors. It draws in warm room air, cools it, and pushes the resulting hot exhaust air outside through a flexible hose, which you seal into a window opening with a supplied window kit. You plug it into a standard 13A socket and switch it on — no pipework, no outdoor unit, no installer. The downsides are that the unit takes up floor space, the exhaust hose has to reach a window, and the compressor sits inside the room, so portables are typically noisier and a little less efficient than fixed systems.
How does a fixed split system work?
A split system “splits” the job across two units: an indoor unit (usually wall-mounted) and an outdoor condenser unit, connected by refrigerant pipework. Because the heat-rejecting compressor lives outside, split systems are generally quieter indoors and more energy-efficient than portables, and they free up floor space. The catch is installation: refrigerant pipework must be fitted and charged by an installer.
Important: refrigerant handling and the law. Fixed split systems contain refrigerant gas. Under UK F-Gas regulations, this refrigerant must only be installed and handled by an F-Gas-certified installer. This is not a DIY job — using an uncertified fitter can be unlawful, unsafe and may invalidate your warranty.
Will I need planning permission?
This depends on your situation, and it is worth checking before you commit to a fixed system.
Portable units sit indoors and vent through a window, so they generally have no planning implications. Fixed external condenser units are different: in some cases an outdoor unit may fall under permitted development, but only where specific conditions on its size and siting are met. The rules differ across England, Scotland, Wales and Northern Ireland, and extra restrictions usually apply to listed buildings and conservation areas. Always check with your local planning authority before installing an external unit. This is general information, not planning advice.
You can start with the GOV.UK Planning Portal for an overview, but your council’s planning department is the authority for your specific address.
Which should I choose?
Choose a portable if you rent, want flexibility, only need to cool occasionally, or want to avoid installation cost and disruption. Choose a split system if you own your home, want the quietest and most efficient option, and are happy to arrange certified installation. Whichever route you take, size it properly first — use our BTU calculator to find the right capacity, and the running cost calculator to compare what each option will cost to run.