Portable air conditioning
A portable unit is a self-contained box on castors with no outdoor unit — it vents warm air outside through a hose fitted to a window. It’s the most flexible option and needs no installation, but it’s worth being clear-eyed: a portable is less efficient, noisier and less powerful than a fixed system. The honest take below should help you decide whether it’s right for your situation.
How it works
A portable contains the whole refrigerant system in one box. It cools the room air and expels the resulting heat outside through a flexible hose at a window. Most are “single-hose”: they draw air from the room to cool the internal condenser and push it outside, which lowers the room’s air pressure slightly and pulls warm air in from the rest of the home — one of the reasons they’re less efficient than a fixed system. See how air conditioning works.
The honest pros and cons
Pros: no installation, no outdoor unit, no planning to think about; you can wheel it between rooms; cheap to buy; the only realistic option when you can’t fit a fixed system (renting, listed buildings, a one-off need).
Cons: noticeably less efficient and more expensive to run than a fixed split; louder, because the compressor is in the room with you; the window hose lets heat and air leak; limited power, so it struggles in larger or sunnier rooms; takes up floor space and may need its condensate water emptied.
Should you buy one? A portable is the right answer when a fixed system isn’t an option — you’re renting, the property won’t allow external units, or you only need cooling occasionally in one room. If you own your home and want efficient, quiet, reliable comfort through the season, a fixed wall-mounted or floor-standing split will do the job far better for less running cost. Be honest about which situation you’re in.
Sizing
Portables are generally smaller, around 2.0–3.5 kW (≈ 7,000–12,000 BTU), and best matched to a single, modest room. Because some output is lost through the hose and air leakage, don’t expect a portable to cool the area a fixed unit of the same rating would. See how to size a system.
What it costs: around £250–£1,000 to buy with nothing to install (2026 guide price), but more expensive per hour to run than a fixed split because of the lower efficiency. See the full home cost guide for how it compares.
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