Do You Need Planning Permission for an Air to Air Heat Pump?

England: permitted development (Class G)

The rules were relaxed in 2025. As described by the government and MCS, an air source heat pump unit is permitted development if:

it complies with MCS 020 (the MCS planning standard), including the noise check
noise is no more than 42 dB at 1m from a neighbour's nearest door or window
there's no more than two units on a detached house, or one on a semi, terrace or block of flats
each unit is no bigger than 1.5 cubic metres on a house, or 0.6 cubic metres on a flat
it isn't on a pitched roof, or within 1m of the edge of a flat roof
it's sited, as far as practical, to minimise its effect on the look of the building and the area

Rules change, so check the current position on the Planning Portal or with your council before installing.

When you will need permission

Cooling-only units. Air conditioning that can't heat isn't covered by permitted development.
Listed buildings. You'll need listed building consent.
Conservation areas. A unit can't go on a wall or roof facing a highway without permission.
Going over the limits on number, size or noise.
Article 4 directions in some areas remove permitted development rights. Your council can tell you.

Flats and leaseholders

Most leases treat the outside walls as the freeholder's property. You'll almost always need written consent from the freeholder or managing agent before fixing an outdoor unit, pipes or trunking to the building. Start this early, because it can take weeks.

Wales, Scotland and Northern Ireland

Each has its own permitted development rules for heat pumps, with different conditions. Check with your council or the Planning Portal (Wales) before installing.

Building regulations

The new electrical circuit is notifiable work under Part P in England and Wales, so it must be done or signed off by a registered electrician.

Questions

Do I need planning permission for an air to air heat pump?

Usually not in England, if it provides heating, is installed to MCS 020 and stays within the limits on size, number, siting and noise. Listed buildings, conservation areas and flats have extra rules.

Do I need planning permission for air conditioning?

Cooling-only air conditioning isn't permitted development in England, so you'll usually need planning permission.

Can I put an air to air heat pump on a flat?

Often, but only one unit is allowed under permitted development on a block of flats, each unit must be no larger than 0.6 cubic metres, and you'll need the freeholder's consent if you're a leaseholder.

Sources

Checked 8 November 2026.