Heat Pump Planning Permission: What You Need to Know

In England, you can install an air source heat pump on a house or a block of flats, or in its grounds, without planning permission if all of the following conditions are met.

Ground source heat pumps are also permitted development in England. Class C of the same Part allows a ground source heat pump within the grounds of a house or block of flats and sets no conditions on size, number or noise.

This is the condition that causes most concern. In England, and in Wales since 1 June 2026, the heat pump must pass the MCS 020(a) sound calculation. It works out the sound level at an assessment position 1 metre outside the centre of any window or door to a habitable room of a neighbouring home, and the result must be 37.0 dB(A) or less. Habitable rooms are rooms used for sleeping or living; bathrooms, toilets, corridors, hallways, utility and laundry rooms and rooms used only for cooking do not count. For a heat pump on a block of flats, the other flats in the block count as neighbours.

The calculation starts from the heat pump's sound power level from its energy label or datasheet, not a quiet mode figure. It adds a correction for hard surfaces within 1 metre of the unit (a unit on the ground against one wall has two), allows for the distance to the window, and takes off up to 10 dB where a solid wall or fence hides the window from the unit. More than three reflecting surfaces, as in a small lightwell, fails outright.

In the worked example in MCS 020(a), a heat pump with a sound power level of 60 dB(A), on the ground against a wall and 8 metres from a neighbour's bedroom window, with a brick wall partly in the way, comes out at 32.0 dB(A), well inside the limit. Terraces and flats, where units sit closer to neighbours' windows, need more care. The older MCS 020 method had a 42 dB(A) limit but counted differently; when MCS tested both, most installations passed the new calculation more easily. Read our heat pump noise guide for what the test means in practice.

If your installation cannot pass the noise test, it is not permitted development, but you can still apply for planning permission. The noise assessment will be part of the application, and the council may approve it with conditions, such as screening.

In England, permitted development for air source heat pumps does not apply to a listed building or anything within its grounds, so you need planning permission. Separately, the Planning (Listed Buildings and Conservation Areas) Act 1990 requires listed building consent for any works that would affect the building's character as a building of special architectural or historic interest. Fixing a unit to the building, drilling through historic walls for pipes or changing the interior can all do that, so ask your council's conservation officer early.

How to apply: Apply to your local planning authority for planning permission and, where needed, listed building consent. Include the proposed heat pump location, unit dimensions, noise data and photographs showing the visual impact. Your MCS installer should be able to provide the technical details.

Timeline: Allow for the council's decision period before you book the installation. Conservation officers may ask for changes to reduce the visual impact, such as moving the unit to a less visible position or adding screening.

Tips for approval: Place the unit in the rear garden or behind an outbuilding rather than on a principal elevation. Use a low-profile unit in a neutral colour. Offer to install acoustic and visual screening. Provide evidence that the installation is reversible (can be removed without damaging the building). Your installer's experience with similar listed properties is valuable here.

Properties in conservation areas in England can install heat pumps under permitted development, with two extra restrictions: the unit must not be on a wall or roof that fronts a highway, and it must not be nearer to any road bounding the property than the part of the house nearest that road. The same applies in World Heritage Sites.

In practice, this means placing the unit in a rear or side garden, or at the side of the house set back from the road.

If your property is listed as well as in a conservation area, permitted development does not apply at all: you need planning permission, and listed building consent for any works that would affect the building's character.

Flats have additional considerations. England's rules allow only one air source heat pump on or within the grounds of a block of flats under permitted development, with an outdoor unit of no more than 0.6 cubic metres, and the noise test treats other flats in the block as neighbours. A second unit on the same block needs planning permission. You will also need the freeholder's or management company's permission, and some leases prohibit external alterations without consent.

In communal areas, you may also need to satisfy other residents and the managing agent that the noise and visual impact are acceptable. That is a leasehold matter rather than a planning one. Read our guide to heat pumps in flats for the full picture.

Scotland: Class 6H of the Scottish order, as amended on 24 May 2024, allows one air source heat pump on a home or in its grounds, and in Scotland that includes flats. Fixed to the building, it must not stick out more than 1 metre from the wall, roof or chimney, and in a conservation area it must be at ground floor level on the rear elevation. A freestanding unit must not be forward of a front or side wall that faces a road, or more than 3 metres high. It is not allowed in a World Heritage Site or the grounds of a listed building, must be used only for heating and hot water, and must meet the MCS planning standards or an equivalent. There is no boundary distance rule and no size limit. Ground source heat pumps are permitted development within the grounds (Class 6D).

Wales: Since 1 June 2026 the Welsh rules broadly match England's: the unit must pass MCS 020(a), up to two units are allowed on a detached house and one otherwise, the outdoor unit can be up to 1.5 cubic metres on a house (1 cubic metre on a block of flats), and there is no boundary distance rule. Before that date, units had to be at least 3 metres from the boundary and no bigger than 1 cubic metre. Listed buildings, scheduled monuments, pitched roofs and walls fronting a road above ground floor level are excluded, as in England.

Northern Ireland: One air source heat pump is permitted within the grounds of a house, but not within 1 metre of the boundary with another house, not forward of a front or side wall facing a road, not on a roof and no more than 3 metres high. In a conservation area or World Heritage Site it must not face onto and be visible from a road. It must meet the MCS planning standards or an equivalent. The Boiler Upgrade Scheme does not cover Northern Ireland.

A good MCS installer will check your property's planning status (listed, conservation area, Article 4 directions) before quoting. They will run the MCS 020(a) sound calculation for each neighbouring window or door, using the heat pump's published sound power level and the distance from the proposed position, and recommend a placement that meets all the conditions. If planning permission or listed building consent is needed, they will advise you on the process and provide the technical documents for the application.

If your installer does not mention planning at all, ask specifically. Use the MCS directory to find certified installers. Get at least three quotes. Read our BUS grant guide for the application process once planning is sorted.

Use our heat pump calculator to estimate costs for your property while you work through the planning requirements.

England: GPDO 2015, Schedule 2, Part 14 and S.I. 2025/560. Wales: GPDO 1995, Schedule 2, Part 40 and W.S.I. 2026/79. Scotland: GPDO (Scotland) 1992, Class 6H. Northern Ireland: GPDO (Northern Ireland) 2015, Part 2, Class G. Noise test from MCS 020(a) Issue 1.1 and the MCS 020 consultation response. Listed building consent from the Planning (Listed Buildings and Conservation Areas) Act 1990 and Historic England. All checked on 25 September 2026.