Most homes in England do not need planning permission for an air source heat pump, because a standard installation on a house counts as permitted development as long as it meets a set of conditions on noise, size, number of units and position. Ground source heat pumps are also usually permitted development. The main exceptions are listed buildings, some installations in conservation areas and World Heritage Sites, flats that already have a unit, and homes where the council has removed permitted development rights.
The rules changed in England on 29 May 2025 and in Wales on 1 June 2026, and a stricter noise calculation became the only accepted route in England on 28 May 2026. Scotland and Northern Ireland run their own systems. This guide sets out the position in each nation as of September 2026, plus the building regulations that still apply once planning is settled.
Do Air Source Heat Pumps Need Planning Permission in England?
No, not usually: an air source heat pump on a house in England is permitted development if it passes the MCS 020(a) noise calculation and stays within the size, number and siting limits in the table further down. Permitted development means national legislation has already granted consent for that type of work, so you do not send an application to the council.
The rules sit in Part 14 of Schedule 2 to the General Permitted Development (England) Order 2015, as amended in 2025 by statutory instrument 2025/560.
What Changed in the May 2025 Rules?
The 2025 amendment, in force from 29 May 2025, scrapped the rule that kept units at least 1 metre from the boundary, raised the size limit for houses to 1.5 cubic metres and allowed two units on a detached house. It also brought air-to-air heat pumps into scope, provided they are not used solely for cooling.
| Rule | Before 29 May 2025 | From 29 May 2025 |
|---|---|---|
| Distance from the property boundary | At least 1 metre | No minimum distance |
| Maximum outdoor unit volume on a house | 0.6 cubic metres | 1.5 cubic metres |
| Units allowed on a detached house | One | Two |
| Units allowed on other houses | One | One |
| Air-to-air heat pumps | Not covered | Covered, if not used solely for cooling |
| Noise standard | MCS 020 (42 dB limit) | MCS 020(a) (37 dB limit), the only accepted route from 28 May 2026 |
What Conditions Must an Air Source Heat Pump Meet Under Permitted Development?
In England the unit must pass the MCS 020(a) noise test, fit within 1.5 cubic metres (0.6 cubic metres on a block of flats), stay off pitched roofs and avoid highway-facing positions in sensitive areas. The full list, taken from the Planning Portal guidance on the 2025 rules, is below.
| Condition | Requirement in England |
|---|---|
| Number of units | Two on a detached house; one on any other house or block of flats. Extra units need planning permission. |
| Size | Compressor unit, including any housing, no more than 1.5 cubic metres on a house or 0.6 cubic metres on a block of flats |
| Noise | Must comply with MCS 020(a) |
| Pitched roofs | Not permitted |
| Flat roofs | Every part of the unit at least 1 metre from the external edge of the roof |
| Walls facing a highway (outside conservation areas and World Heritage Sites) | Not above ground floor level |
| Conservation areas and World Heritage Sites | Not on a wall or roof that fronts a highway, and not nearer to a bounding highway than any part of the house |
| Listed buildings and scheduled monuments | No permitted development within the curtilage |
| Use | Must not be used solely for cooling |
| Siting | Positioned to minimise its effect on the building’s appearance and the amenity of the area |
| Removal | Taken away as soon as reasonably practicable once no longer needed |
Two other things can remove the right altogether. A council can issue an Article 4 direction that withdraws permitted development in a defined area, and some newer estates were approved with planning conditions that do the same. Your council’s planning map or the property’s planning history will show either. If you already have a wind turbine at the property, speak to the council before assuming a heat pump is covered.
What Noise Limit Does a Heat Pump Have to Meet?
In England, a heat pump fitted under permitted development must pass the MCS 020(a) sound calculation, which sets a limit of 37 dB LAeq over 5 minutes at the assessment position. That position is 1 metre outside the centre of a door or window to a habitable room of a neighbouring property.
The calculation starts with the unit’s sound power level, which MCS holds on its product directory, then adjusts for distance, reflecting walls and any barrier between the unit and the window. A solid masonry wall that blocks the line of sight can take up to 10 dB off the result. With the 1 metre boundary rule gone, this calculation now does most of the work in deciding where a unit can go.
The older MCS 020 standard used a 42 dB limit with a different method, so the two figures are not directly comparable. MCS 020(a) became mandatory for MCS installers fitting units under permitted development on 20 September 2025, and from 28 May 2026 it is the only standard accepted for permitted development in England. On a detached house with two units, both are assessed together. If the calculation fails, our surveyors will usually look at a different wall, a quieter model or a barrier before anyone mentions a planning application.
Do Ground Source Heat Pumps Need Planning Permission?
Usually not, because the Planning Portal treats a ground source or water source heat pump at a house in England as permitted development in most cases.
Two checks still apply. If the house is listed or in a conservation area, confirm the position with the council first. Separately, since 2 October 2023 a new closed-loop ground source system in England may need an Environment Agency permit, unless it meets the exemption conditions or, for a single home, complies with regulatory position statement RPS 307. Your installer should confirm which applies before drilling or trenching.
What If I Live in a Listed Building, Conservation Area or World Heritage Site?
A listed building has no permitted development rights for an air source heat pump, so you will need planning permission and, where the work affects the building’s character, listed building consent as well. This applies anywhere within the curtilage, so a unit at the bottom of the garden is caught too.
Conservation areas and World Heritage Sites keep permitted development, with tighter siting. The unit cannot go on a wall or roof that fronts a highway, and it cannot sit closer to a road bounding the property than the house itself. For a listed home, expect a longer lead time and speak to the conservation officer early.
Can I Fit a Heat Pump to a Flat or Leasehold Property?
In England, a block of flats gets permitted development for the first air source heat pump only, and its compressor unit must be no larger than 0.6 cubic metres; any further unit on the same building needs planning permission. That means the first flat owner to fit one uses up the allowance for the whole block.
Planning is only half of it for leaseholders. Most leases restrict alterations to the structure and use of communal areas, so you will usually need written consent from the freeholder or management company before fixing a unit to an outside wall or placing it on shared land. Permitted development does not override a lease.
How Do the Rules Differ in Wales, Scotland and Northern Ireland?
Each nation sets its own permitted development rules: Wales now closely follows England after its June 2026 changes, Scotland still allows only one air source heat pump per building, and Northern Ireland keeps a 1 metre boundary rule. The table compares the main points.
| Rule | England | Wales | Scotland | Northern Ireland |
|---|---|---|---|---|
| Boundary distance | None | None (was 3 metres) | No boundary distance in Class 6H | At least 1 metre from the boundary of another dwelling |
| Number of units | Two on detached houses, otherwise one | Two on detached houses, otherwise one | One per building or curtilage | One per curtilage |
| Size or projection | 1.5 cubic metres (0.6 on flats) | 1.5 cubic metres (was 1) | No more than 1 metre projection from a wall or roof; 3 metres high if in the garden | No more than 3 metres high |
| Noise standard | MCS 020(a), 37 dB | MCS 020(a), 40 dB | MCS 020 or equivalent | MCS 020 or equivalent |
| Roofs | Flat roofs only, 1 metre from the edge | Flat roofs only, 1 metre from the edge | Within the 1 metre projection limit | Not permitted |
| Conservation areas | Not on or nearer to a highway-facing elevation | Not on or nearer to a highway-facing elevation | Ground floor, rear elevation only | Not visible from a road |
| World Heritage Sites | Same as conservation areas | Check with the council | Not permitted development | Not visible from a road |
| Listed buildings | Not permitted development | Not permitted development | Not permitted development | Needs prior consent |
What Changed in Wales on 1 June 2026?
From 1 June 2026, Wales removed its 3 metre boundary rule, raised the size limit from 1 to 1.5 cubic metres and allowed two units on detached homes, with both units together meeting a 40 dB limit under MCS 020(a). Air-to-air heat pumps are now covered, and units can go on highway-facing walls outside conservation areas. Pitched roofs remain off limits, and a unit cannot be added if a standalone wind turbine is already in the curtilage. Ground source and water source heat pumps remain permitted development in Wales. Flat owners should ask the council, as the Welsh guidance is written for houses.
What Are the Current Rules in Scotland?
Scotland allows one air source heat pump per building or curtilage under Class 6H, covering houses and buildings containing flats, as long as no part sticks out more than 1 metre from the wall or roof. The Scottish Government’s Circular 1/2024 sets out the detail. In a conservation area the unit must be at ground floor level on the rear elevation. It cannot be in a World Heritage Site or the curtilage of a listed building, and a garden unit cannot sit forward of a road-facing principal or side elevation. Ground source and water source heat pumps are permitted development under Classes 6D and 6E.
What Are the Current Rules in Northern Ireland?
Northern Ireland made air source heat pumps permitted development on 4 July 2023, provided the unit is at least 1 metre from a neighbouring dwelling’s boundary and meets the MCS 020 noise standard. Only one unit is allowed per curtilage. It cannot be roof-mounted, sit forward of a road-facing principal or side elevation, or exceed 3 metres in height, and in conservation areas and World Heritage Sites it must not be visible from a road. For ground source systems, confirm with your council before any groundworks.
What Happens If My Heat Pump Does Not Qualify as Permitted Development?
You apply to your local council for householder planning permission, and the Planning Portal says most applications are decided within eight weeks. The application normally includes a site plan, elevations showing the unit and the noise calculation.
Before applying, check whether a small change brings the job back within permitted development. Moving the unit to another wall, choosing a quieter model or adding a solid barrier often fixes a failed noise calculation. If you want written proof that an installation is lawful, for example before selling the house, you can apply for a Lawful Development Certificate instead. Do not fit a unit that needs permission before you have it, as the council can take enforcement action.
Which Building Regulations Apply to a Heat Pump Installation?
A heat pump must meet the Building Regulations even when no planning application is needed, because planning and building regulations are separate regimes. In England and Wales the parts that matter most are Part L for energy efficiency and Part P for the electrical work.
| Requirement | What it covers | How it is usually handled |
|---|---|---|
| Part L (energy efficiency) | New and replacement wet heating systems designed for a maximum flow temperature of 55°C, in force since 15 June 2022, plus controls and commissioning | Installer’s design and commissioning records |
| Part P (electrical safety) | A new circuit or new consumer unit is notifiable work | Electrician registered with a competent person scheme self-certifies; otherwise building control inspects |
| Building control notification | Confirms the heating work complies | Competent person scheme installer notifies on your behalf, or you apply to building control |
| MCS certification | Design, installation and the MCS 020(a) noise calculation | MCS certificate issued at handover |
Keep all the certificates together, as buyers’ solicitors will ask for them. Scotland and Northern Ireland have their own building standards systems, and your installer should confirm what applies there.
How Can I Check My Own Home Before Booking a Survey?
Start with your council’s online planning map, which shows whether the property is listed, in a conservation area or covered by an Article 4 direction. Then check the lease if you own a flat, and note where your neighbours’ nearest windows are, because that drives the noise calculation.
If none of those flags apply and you live in a house, an air source heat pump will very likely be permitted development. If something does apply, it rarely stops the project; it usually means a planning application and a few extra weeks. Our surveyors run the MCS 020(a) calculation during the home visit, so you will know where the unit can go and whether permission is needed before you commit to a quote.
