Set up your portable AC.

A portable air conditioner is the cheapest way to cool a single UK room without altering the building — typical units cost £250–£700 to buy, and a tradesperson will set one up properly for £80–£180 if you want help with venting, the window kit and the condensate drain. Most setups take 1–2 hours.

Portable AC is the right pick for renters, listed buildings, and rooms where a permanent split-system can't be fitted. It's noisier and less efficient than a fixed unit, but it requires no structural work and you can take it with you.

What a setup actually involves

"Plug in and switch on" works for the lucky few. Most homes need a bit more thought to get a unit running well:

• Venting the hot exhaust — every portable AC needs to push hot air outside via a hose. The window-bracket kit that ships in the box rarely fits sash, casement-with-trickle-vent, or tilt-and-turn windows without modification.
• Sealing the gap — a good install seals the window opening with foam or a custom panel so cooled air doesn't escape and warm air doesn't pour back in. Skip this and the unit struggles.
• Condensate drain — single-hose units pump moisture out through the exhaust; some dual-hose units have a tray that needs emptying or a continuous drain hose to a sink or outside.
• Power — a 12,000 BTU unit pulls around 1.1 kW. Avoid sharing the socket with kettles, microwaves or fan heaters on an old ring main.

Typical UK costs

Estimates only — prices vary by region, access and unit type. London and the South East run 15–25% above the national average for tradesperson time.

Single-hose vs dual-hose units

If you're choosing the unit yourself, this is the spec that matters most. Single-hose models are cheaper and lighter but pull room air to cool the condenser, which creates negative pressure and sucks warm outside air back in through gaps. Dual-hose models (separate intake and exhaust) are roughly 30% more efficient in real use but cost £100–£250 more. For rooms over 20 m², dual-hose is worth the premium.

Things people often miss

• BTU sizing — a 7,000 BTU unit won't cool a 25 m² south-facing room. Rule of thumb: 600–650 BTU per m² of floor area, more if the room is sunny or has a lot of glazing.
• Noise — portable units run at 50–65 dB, similar to a dishwasher. Don't put one in a bedroom unless you've checked the spec.
• Hose length — exhaust hoses should be as short and straight as possible. Long, looped or bent hoses re-radiate heat back into the room and kill efficiency.
• Listed buildings + leases — if you're drilling a wall vent for a permanent install, check freeholder/leaseholder rules and conservation status first. A reversible window kit avoids all of this.

Frequently asked questions

Want a local pro to handle this? A qualified installer can size, vent and seal a portable AC properly in an hour or two — the difference between a unit that actually cools your room and one that just makes noise.