For most homes, fitting an air source heat pump needs no planning application. It is treated as permitted development, which means the government has already granted permission in principle, provided the installation stays inside a set of conditions. The one that catches people out is not the size of the unit but the noise it makes at the neighbour's window, and your installer has to prove it passes before the job counts as permitted. The cases that genuinely need an application are the usual ones: listed buildings, some conservation area sitings, and flats. This guide sets out where the line falls, so you know whether to book a survey and get on with it or ring the council first.
The short answer. An air source heat pump on a typical house in England is usually permitted development and needs no planning application, as long as there is one unit, it sits within the size and siting limits, it is not in the grounds of a listed building, and it passes the standard noise assessment at the nearest neighbour's window. You will normally need an application for a listed building, for some conservation area sitings that face a road, and for a flat. England relaxed several of these conditions in 2025, and Scotland, Wales and Northern Ireland set their own rules, so confirm the current position with your local planning authority before you commit.
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What permitted development means for a heat pump
Planning law in England lets you make certain changes to your home without applying each time, because a blanket permission already exists for them. These are permitted development rights, and a single air source heat pump at a house falls under them when it meets the conditions. The practical effect is that most installations can go ahead without the cost, delay and uncertainty of a planning application. Your installer handles the unit and the pipework, you deal with any grant paperwork, and planning does not enter into it for the typical case.
It helps to say plainly that this is the normal route, not a loophole. The government widened these rights deliberately to make heat pumps easier to fit, which is part of why they are spreading. If you are still weighing up whether a heat pump suits your home at all, the heat pumps explained guide covers how they work, and heat pump grants and cost covers the money. The planning question, for most people, has a short answer: there is nothing to apply for.
The conditions an air source unit has to meet
Permitted development comes with strings, and your installation has to stay inside them to qualify. For an air source heat pump at a house in England the main conditions are these, and a competent installer will design around them without being asked:
| Condition | What it means in practice |
|---|---|
| Noise | The unit must pass a standard noise assessment measured at the nearest neighbour's window. This is the condition most likely to decide siting. |
| One unit | Historically only a single heat pump counted as permitted development per property, though England eased this in 2025 for some homes. |
| Size of the outdoor unit | The compressor has to stay within a volume limit. England increased that limit in 2025, so a larger unit now qualifies than before. |
| Position from the boundary | A one metre gap from the property boundary used to apply in England and was removed in 2025, but check your nation's current rule. |
| Siting and appearance | The unit should be placed to keep its effect on the look of the building and the area as small as is reasonable, and removed when no longer needed. |
General conditions for a domestic air source heat pump in England. The detail changed in 2025 and continues to be reviewed, so confirm the current limits for your property with your local planning authority or the Planning Portal.
The reason the exact figures are worth checking rather than memorising is that this is a moving target. England loosened the rules in 2025 to let bigger units go in, dropped the old boundary gap, and made it easier to fit a pump at a terraced or semi-detached house. That is good news, but it means a rule of thumb you read a couple of years ago may now be out of date in your favour. Ask your installer to confirm in writing that the design meets the current permitted development conditions for your address.
The noise test is the one that actually bites
Of all the conditions, noise is the one that most often shapes where the unit goes, and occasionally whether it qualifies as permitted development at all. The standard used in the industry, known as the MCS planning standard, requires the installer to run a calculation showing the sound from the unit does not exceed a set level, around 42 decibels, measured at the nearest habitable room window of a neighbouring property. Forty two decibels is quiet, roughly the hum of a fridge heard from across a room, but a unit sited a metre from a bedroom window on a tight plot can still fail it.
In practice this is why installers care so much about position. Putting the unit on a gable wall away from neighbours, giving it clear air so it is not boxed in, and keeping it off a shared boundary all help it pass. A good surveyor works this out at the quote stage, not after the unit is bolted down. If your plot is small and the only sensible spot is close to next door, the noise assessment is the thing most likely to force a rethink, so raise it early. Modern units are far quieter than the ones that gave heat pumps a noisy reputation a decade ago, and this quietness is also what lets them run gently through the night, which matters for the way they keep a home warm in cold weather.
Ground source heat pumps and boreholes
Ground source systems raise a different question, because the heat pump itself sits indoors and makes little outdoor noise. The collector, whether buried in trenches or sunk down a borehole, is usually permitted development as far as planning goes. The catch is elsewhere: deep boreholes can need their own notifications, and a system that takes water from the ground, rather than circulating fluid in a sealed loop, may need an abstraction permit from the environmental regulator. If you are choosing between the two types, the ground versus air source comparison weighs the cost and disruption, and the planning side is one more reason most homes end up with air source: it is simpler to site and simpler to approve.
When you still need to apply
Several situations take you outside permitted development, and in these you should assume an application is needed until the council says otherwise.
Listed buildings. If your home is listed, a heat pump in its grounds falls outside permitted development and you will need consent, because the protection covers the setting and not just the building. Many listed homes do get pumps approved on a discreet elevation, so it is worth a conversation with the conservation officer rather than assuming no.
Conservation areas and World Heritage Sites. You can often still use permitted development here, but a unit sited on a wall or roof that faces a road, or nearer to the highway than the house, is usually not permitted and needs an application. A unit tucked in a back garden out of public view is frequently fine. The test is largely about what can be seen from the street.
Flats and maisonettes. Permitted development rights for heat pumps apply to houses, not flats, so a flat normally needs planning permission. You will also need the freeholder's agreement and, in a block, a sensible spot for the unit that the management company will accept, which is often the harder part than planning itself.
Scotland, Wales and Northern Ireland
The broad principle, that a single domestic air source heat pump is usually permitted development, holds across the UK, but the detailed conditions, the noise rules and the way listed and conservation protections work are set separately by each nation and do differ. The safest approach wherever you live is the same: treat a well sited unit on an ordinary house as very likely permitted, and treat anything involving a listed building, a conservation area, a flat or a tight boundary as a case to check directly. A short call to your local planning authority, or a look at the Planning Portal for your nation, settles it before you spend a penny.
Planning is not the same as building regulations or MCS
These three get muddled, so keep them apart. Planning permission is about whether you are allowed to put the unit there. Building regulations are about whether the work is done safely and correctly, including the electrics and the pipework. MCS certification is a quality standard that your installer works to, and it is usually what the government grant and any export arrangement depend on. Even when you need no planning application, the installation must still meet building regulations, and if you want the grant it must be done by an MCS certified installer who completes the noise assessment as part of the job. None of that disappears just because planning does, so always use a properly certified installer rather than the cheapest quote that skips the paperwork.
What I would check before booking a survey
Run through a short list and you will rarely be caught out. Is the property listed, or in a conservation area or World Heritage Site? Is it a flat rather than a house? Would the only sensible spot for the unit face a road, or sit close to a neighbour's window? If the answer to all of those is no, you are almost certainly looking at permitted development and can proceed. If any is yes, ring your local planning authority before signing anything, and ask the installer to confirm in writing that they have accounted for it and that the noise assessment passes. A good installer raises these points unprompted and treats the noise calculation as part of the quote, not an afterthought. To price the running cost once the planning question is settled, the running cost calculator and the grants and cost guide will do the sums.
Common questions
Do I need planning permission for an air source heat pump?
Usually not. A single air source heat pump at a typical house in England is permitted development and needs no application, provided it meets the size and siting limits and passes the standard noise assessment at the nearest neighbour's window. England relaxed several of these conditions in 2025, so check the current rules for your address.
What is the noise limit for a heat pump under permitted development?
The industry noise standard requires the sound at the nearest neighbour's habitable room window to stay below a set level, around 42 decibels. Your installer runs this calculation as part of the job, and it is the condition most likely to decide where the unit goes.
When does a heat pump need planning permission?
Common cases are a listed building, a unit sited on a road-facing wall or roof in a conservation area, and any installation at a flat or maisonette. If any of these applies, check with your local planning authority before committing.
Do ground source heat pumps need planning permission?
The buried collector is usually permitted development, and the heat pump sits indoors so noise is rarely an issue. The paperwork tends to be elsewhere: deep boreholes can need notifications, and a system that abstracts groundwater may need an environmental permit.