Do I need planning permission for air conditioning?

The rules changed on 29 May 2025. Before then, the permitted development right for air source heat pumps covered units used solely for heating, which shut air conditioning out. The 2025 amending order replaced that with a condition that the unit is not used solely for cooling, so a reversible split that heats the room in winter now falls within the right on a house or a block of flats, subject to its limits.

The limits still matter. A house gets one unit, or two if it is detached; each outdoor unit must stay under 1.5 cubic metres, which a domestic condenser does with room to spare; it cannot go on a pitched roof; and it must be sited to keep its effect on the building's appearance and the neighbours' amenity as small as practicable. The government's June 2026 guidance adds that in most cases a small home needs no planning permission if the unit does not materially change how the building looks from outside, and asks councils to take a common-sense approach.

Three situations still need the formal route. Listed buildings get no permitted development, and fixings to historic fabric need listed building consent. In conservation areas the unit cannot go on a wall or roof facing a road, and an Article 4 direction can remove the right on particular streets; conservation areas cover a large share of inner London, including most of Westminster and Kensington & Chelsea. And a unit used only for cooling sits outside the right.

Flats have one extra limit: permitted development covers only the first air source heat pump on the whole block, up to 0.6 cubic metres, and your lease needs the freeholder's written consent whatever planning says. At survey we check which rules apply to your building, site the condenser where its visual and noise impact are lowest, and tell you when an application is the right call. The install stays a one-day job; any paperwork comes first.

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