Air conditioning guides

In 2026 a single-room wall-mounted air conditioner typically costs £1,150–£2,450 fitted including VAT, a two-to-four-room multi-split £2,450–£6,950, and a concealed ducted system £5,450–£12,950. London sits roughly a third above the UK middle and the South East about a fifth above, while Scotland, Wales and the North East sit a little below it.

A modern inverter split system uses roughly a third to a fifth of its cooling or heating output in electricity. A 2.5 kW unit cooling a bedroom often draws around 0.5–0.8 kW at full output and much less once the room is at temperature, so running costs are usually pence per hour rather than pounds.

As a starting point, many UK bedrooms and studies need about 2–2.5 kW of cooling, average living rooms 3.5 kW and large or sunny open-plan rooms 5–7 kW. The right size depends on glazing, orientation, insulation and how the room is used, so a room-by-room heat load check is the reliable way to size a system.

Portable air conditioners are cheap and need no installation, but they are noisy, less efficient and vent hot air through a hose in a window. A fixed split system costs more to buy and fit, but it cools far better, runs quietly, heats efficiently in winter and is cheaper to run.