Domestic air conditioning and heat pump installations have become increasingly common in the UK as summers grow warmer. Whether planning permission is required depends on the type of unit, its position, and the property's planning status.

Permitted Development for Air Source Heat Pumps and Air Conditioning

Under Class G of Part 1 of the General Permitted Development Order, the installation of a single air source heat pump on a dwellinghouse is permitted development, subject to conditions. From 2023 this class was extended to include stand-alone air conditioning units that use the same technology as air source heat pumps. The conditions require that the unit is not installed on a roof that faces and is visible from a highway, is not installed on a wall that faces and is visible from a highway if above the ground floor, is not within one metre of the property boundary, is not at a listed building, and does not result in there being more than one air source heat pump on the same building or its curtilage.

The key practical conditions are therefore the single-unit limit, the position away from highway-facing walls above ground floor level, and the boundary setback. Many domestic wall-mounted split system units can be installed on rear or side walls under permitted development.

Conservation Areas and Listed Buildings

In conservation areas, the permitted development right for air source heat pumps and air conditioning on walls and roofs visible from a highway is removed. Planning permission is required for any unit on a wall or roof visible from a highway in a conservation area. At listed buildings, listed building consent is required for any installation that affects the fabric of the building, regardless of visibility.

Noise Considerations

Air conditioning units generate noise from the compressor and fan when operating. Permitted development for heat pumps and air conditioning includes a noise condition: the unit must not result in a level of noise exceeding 42 decibels at one metre from any window or door of a neighbouring residential building, averaged over a 15-minute period when operating at its maximum output. This standard is set to protect neighbours from excessive noise disturbance.

Multiple Units

The single-unit permitted development limit means that if you already have an air source heat pump installed, a second air conditioning unit on the same property requires planning permission regardless of position or noise level.

Summary

A single domestic air conditioning or heat pump unit is generally permitted development on a dwellinghouse, provided it is not on a highway-facing wall above ground floor level, is within one metre of the boundary, meets the noise standard, and is not at a listed building. Conservation area properties require planning permission for units visible from a highway. Second units always require planning permission. Noise compliance is a condition of the permitted development right and must be assessed before installation.