Every June, portable air conditioning units sell out across the UK. They are cheap, available immediately, and need no installation.
So are they any good? Sometimes, genuinely, yes. But it depends entirely on what you need, and the differences are bigger than most people expect.
The short answer
A portable unit makes sense if you rent, you need cooling in days rather than weeks, you only want it for a few weeks a year, or you cannot install anything permanent.
A fixed system makes sense if you own your home, you want a room genuinely cool rather than slightly less hot, you care about noise, or you want heating in winter as well.
How they actually differ
| Portable unit | Fixed system | |
|---|---|---|
| Upfront cost | £200–£600 | £1,500–£3,000+ per room |
| Installation | None | Half a day to a day |
| Running cost per hour | 35p–70p | 10p–30p |
| Noise in the room | 50–65 dB | 19–35 dB |
| Cooling power | Modest | Substantially greater |
| Heats in winter | Rarely | Usually |
| Window | Must stay open | Stays shut |
| Lifespan | 3–5 years | 12–20 years |
| Storage | Needs cupboard space | None |
Why portable units struggle
The hose problem. A portable unit works by pushing hot air out through a hose in a window. That hose has to go somewhere, which means a window propped open — and warm outside air flows back in around it. You are cooling the room and heating it at the same time.
The whole machine sits in the room. A fixed system puts the noisy, hot part outside. A portable keeps everything indoors, which means the compressor noise is in the room with you, and some of its own waste heat is too.
Running costs are higher. Because portables fight against air coming back in, they run for longer to achieve less. Expect roughly two to three times the hourly cost of a fixed system doing the same job.
Noise. Most portables run at 50 to 65 decibels — somewhere between a conversation and a vacuum cleaner. Fixed indoor units typically run at 19 to 35 decibels, quieter than a fridge. This is the single biggest complaint from people who try a portable in a bedroom.
Where a portable genuinely wins
You rent. No landlord permission, nothing fixed to the wall, it comes with you.
You need it this week. A fixed system means a survey and a booking. A portable means a trip to a shop.
Occasional use. If you need cooling for a handful of nights a year, the maths does not justify a permanent system.
Listed or restricted properties. Where an external unit is not permitted, a portable may be the only option.
Testing the idea. Some people buy a portable, find they use it constantly, and that is what convinces them to install properly.
The cost over time
A portable at £400 looks far cheaper than a fixed system at £2,000. Over a single summer it is.
Over ten years it is closer than it looks. Portables last three to five years, so you buy two or three. Running costs are two to three times higher. And a fixed system heats in winter, which a portable cannot do at all.
That is not an argument against portables — it is an argument for being clear about which problem you are solving.
Frequently asked questions
Are portable air conditioners any good?
For short-term, occasional or rented situations, yes. They cool a room noticeably. They are louder, less powerful and more expensive to run than a fixed system, and they need a window open.
Do portable air conditioners need a window?
Yes. The exhaust hose has to vent somewhere, and that means a window or a vented panel. Running one without venting simply heats the room.
Why is my portable air conditioner not cooling the room?
Usually the hose. If warm air is leaking back in around the window, or the hose is long and uninsulated, the unit cannot keep up. Window sealing kits help considerably.
Are portable air conditioners expensive to run?
More expensive than fixed systems — typically two to three times per hour for the same cooling effect, because of the air leaking back in.
Can portable air conditioners heat a room?
A few can, but inefficiently. Fixed systems heat efficiently and can be cheaper to run in mild weather than a gas boiler.
Is it worth getting air conditioning installed in a UK home?
If you use cooling more than a handful of days a year, want bedrooms quiet enough to sleep in, or want heating in winter too, yes. If it is a few nights in July, a portable is the sensible choice.
Thinking about a fixed system?
Evergreen Air Conditioning installs across Essex, Hertfordshire, London, Cambridgeshire, Kent and Suffolk. Our free survey includes honest advice about whether a fixed system is right for you.
Book a free survey or call 08081 781 678.
