What is a portable air conditioner?

A portable air conditioner is a self-contained cooling appliance for a single room. It has a compressor, two sets of coils and two fans in one case, mounted on castors, and it vents the heat it removes through a flexible hose into a window. Plug it into a 13A socket, fit the hose and it starts cooling within minutes.

That convenience is the whole appeal. A portable air conditioner needs no drilling, no installer and no landlord's permission in most cases, so it suits rented flats, leasehold homes, sash windows and anywhere a fixed system is impractical. The trade-off is that everything sits inside the room: it is louder and less efficient than a split system that keeps the noisy compressor outdoors.

Catalogue figures reflect UK retailer listings checked on 15 April 2026; prices move, so treat them as a guide.

A portable air conditioner does not make cold air. It moves heat from the room to the outside using the same refrigeration cycle as a fridge. The refrigerant inside absorbs heat indoors, gets compressed so it becomes hotter than the outdoor air, then releases that heat through the exhaust hose.

1. Intake. A fan draws warm, humid room air across the front of the unit.
2. Cooling and drying. The air passes over ice-cold evaporator coils. Heat moves into the refrigerant and moisture condenses into water.
3. Compression. The compressor squeezes the refrigerant gas, raising its pressure and temperature.
4. Heat release. Hot refrigerant flows through the condenser coils at the back, where a second fan blows the heat out through the exhaust hose.
5. Expansion. The refrigerant cools and turns back into a liquid, ready to absorb more heat.
6. Cool air out. The cooled, drier air is blown back into the room.

The water collected in step two is usually evaporated and carried out with the exhaust air. In very humid weather the internal tank can fill, and many units then show a “full” light or need draining through a port at the back. Our maintenance guide covers how to handle it.

Single-hose

The most common and cheapest design. One hose carries hot air out, but the unit also draws room air across the condenser to cool it. That air has to be replaced, so warm air leaks in around doors and windows and works against the cooling. Fine for small rooms and occasional use.

Dual-hose

Two hoses: one pulls outdoor air in to cool the condenser, the other sends it back out. Room air is not wasted, so cooling is faster and more even. They cost more and need a wider window opening. See single vs dual hose for the trade-offs.

Hose-in-hose

One thick hose with a second tube running inside it. It behaves like a dual-hose unit but needs only one hole in the window kit, which makes it popular for sash and small windows.

Portable split

A separate indoor and outdoor unit joined by a refrigerant pipe. Quieter and more efficient, but it needs a hole through the wall and a professional fit, which defeats most of the point of going portable.

Most British homes were built to keep heat in, not out, and few have any cooling. Summer 2026 made that obvious: the Met Office provisionally ranks it the warmest UK summer on record, with a mean temperature of 16.5°C against the previous record of 16.1°C in 2025, and a peak of 38.1°C at Kew Gardens on 13 August.

A fixed split system is the efficient answer, but it is not an option for many tenants, leaseholders or owners of listed buildings. A portable air conditioner fits those cases: nothing is attached permanently, it works in a sash window with the right kit and it moves to the bedroom at night.

Across the 49 portable air conditioners in our catalogue, prices run from £256.99 to £3,999.95, with a median of £409.99. Bigger-capacity and feature-rich models (dual hose, inverter, app control) tend to sit at the top of that range.

Running cost depends on the unit's power draw and the electricity price. Under the Ofgem price cap for 1 October to 31 December 2026, electricity averages 26.32p per kWh, with VAT removed from electricity bills until 31 March 2027.

These are worst-case figures with the compressor running flat out. Once a room reaches the set temperature the compressor cycles off, so real bills are usually lower. Use the running cost calculator to try your own hours and tariff.

A fan is the right first step for mild days because it costs pennies to run. When overnight temperatures stay above 20°C or a south-facing room tops 28°C, a fan only moves hot air around and a compressor-based unit is what actually lowers the temperature.

Ready to choose? Start with the how to choose a portable air conditioner checklist, then compare real models on our best portable air conditioners page.