installation

By James Mitchell, Lead Writer, Renewable Energy · Energy efficiency analyst · Last reviewed

Permitted Development Heat Pump Rules: December 2024 Changes

First published

TL;DR

  • On 29 December 2024, England relaxed permitted development (PD) rights for air source heat pumps, removing the old rule that kept units at least 1 metre from your property boundary.
  • Two air source heat pumps can now qualify as permitted development on a single home, where previously only one did.
  • The 0.6m³ volume cap stayed the same in the December 2024 change, and separate proposals to raise it further were still moving through the system in mid-2026.
  • The MCS 020 noise test still applies: your unit must sit at or below 42 dB(A) at the nearest neighbouring habitable-room window.
  • Conservation areas, listed buildings, and flats remain the big exceptions where you usually still need a full planning application.

Roughly four out of five heat pump installations in England go ahead without a planning application, and the December 2024 rule change pushed that share higher. According to the Boiler Upgrade Scheme statistics collection published by the Department for Energy Security and Net Zero, tens of thousands of grant-backed heat pumps are now installed every year, and the planning route is one of the first questions every homeowner asks. The December 2024 reform to permitted development answered part of that question by scrapping one of the most awkward restrictions in the old rulebook.

I am James Mitchell, and I have covered UK heating policy for more than eight years. This guide sets out exactly what changed in December 2024, what stayed the same, and how the rules read in July 2026. Whether you are fitting an air source heat pump on a terraced house or weighing up a listed cottage, you will finish this page knowing whether your project is a simple notification or a full application.

Table of Contents

What Changed on 29 December 2024?

The headline change was the removal of the 1 metre boundary rule for air source heat pumps in England, which took effect on 29 December 2024. Until that date, a heat pump had to sit at least one metre from the edge of your property to qualify as permitted development. On narrow plots, terraces, and semi-detached homes, that single line disqualified a huge number of otherwise sensible installations and forced owners into full planning applications they did not really need.

The reform did two main things. First, it deleted the 1 metre boundary condition, so a compliant unit can now sit closer to a fence or party line and still count as permitted development. Second, it allowed a second air source heat pump to be installed under permitted development on the same house, where the previous wording capped it at one. That second point matters for larger properties, where a single unit is not always big enough to carry the whole heat load.

The change was delivered through an amendment to the Town and Country Planning (General Permitted Development) (England) Order 2015, the master document that lists what you can build without a planning application. Heat pumps live in Part 14 of Schedule 2 of that order, which you can read in full on legislation.gov.uk. The government also updated its permitted development rights for householders technical guidance to reflect the new position.

One thing the December 2024 change did not do was scrap the noise test or the volume cap. Those conditions carried over intact, and I cover them below because getting them wrong is now the most common way to lose permitted development status.

What Permitted Development Actually Means

Permitted development is a national grant of planning permission that lets you carry out certain works without applying to your local council, provided you meet every condition attached to it. It is not a loophole and it is not a grey area. If your heat pump ticks all the boxes in Part 14, it is lawful. If it misses even one box, it is not permitted development and you need a full planning application.

There is an important trap here. Permitted development covers the planning question only. It does not touch building regulations, which apply to almost every heat pump regardless of the planning route. Your MCS-certified installer normally handles the building regulations side through a competent person notification, so you rarely deal with it directly, but it still exists in parallel to the planning rules.

The Planning Portal, the government-backed planning service, keeps a plain-English summary of the heat pump position on its heat pumps guidance page. It is the page I point most homeowners to first, because it tracks the current wording without the legal density of the statutory instrument itself.

If you are unsure whether your specific plan qualifies, you can apply to your council for a Lawful Development Certificate. That certificate is a formal confirmation that your works are permitted development, and it is useful evidence when you come to sell. You can find the general planning route on GOV.UK.

The Conditions Your Heat Pump Must Still Meet

Even after December 2024, an air source heat pump in England only stays within permitted development if it meets the volume, noise, siting, and single-installation conditions set out in Part 14. These are the parts homeowners most often overlook, so treat them as a checklist.

Volume. The outdoor unit must not exceed 0.6 cubic metres, measured as the external volume of the compressor housing. That is roughly the size of a large chest freezer. Most domestic units on the UK market sit comfortably inside that figure, but a few of the largest single-phase machines edge close to it, so check the manufacturer datasheet before you commit.

Noise. The installation must comply with the MCS 020 planning standard, which in practice means the sound at the nearest neighbouring habitable-room window must not exceed 42 dB(A). Your installer runs this calculation using the MCS noise tool, factoring in the unit, its position, and any reflective surfaces such as walls or fences. The MCS consumer heat pump guidance explains why this test sits at the centre of the permitted development regime.

Siting. The unit cannot go on a pitched roof, and it cannot sit on a wall or roof of a building that fronts a highway if it would be higher than the highest part of the roof. It must also be sited to minimise its visual impact and removed when no longer needed for microgeneration.

Flats and maisonettes. Permitted development for heat pumps applies to houses. If you live in a flat or maisonette, the PD route usually does not help you, and you should assume a full planning application. I dig into that scenario in the guide on whether a heat pump for a flat is possible in the UK.

For a broader walk-through of the wider rulebook, including the pre-December history, see our companion guide on heat pump permitted development rights and what changed.

Where the Old Rules Still Apply

Conservation areas, listed buildings, and designated land keep tighter controls, and the December 2024 relaxation did little to ease them. If your home carries any of these designations, do not assume the new boundary freedom applies to you.

In a conservation area, an air source heat pump cannot be installed on a wall or roof that fronts a highway, and it cannot go on any wall or roof if it would be visible from the road in a way that harms the area's character. On some Article 4 direction streets, permitted development for heat pumps is withdrawn entirely, so a full application is unavoidable. Our guide on heat pumps in a conservation area covers the specifics.

Listed buildings are a separate and stricter regime. Permitted development rights do not extend to works that affect a listed building's special interest, and you will usually need listed building consent on top of, or instead of, planning permission. The detail sits in our guide on heat pumps for a listed building.

Noise complaints remain the single most common way a compliant-looking installation still lands you in trouble, even outside protected areas. A unit that passes the MCS 020 calculation on paper can still generate a statutory nuisance complaint if it is poorly sited or badly commissioned. Our dedicated guide on heat pump noise regulations in the UK explains your rights and your neighbour's.

Scotland, Wales, and Northern Ireland

The December 2024 change applied to England only, and the other three nations run their own permitted development regimes with different wording. This is a point that trips up a lot of online guidance, which quietly assumes England-wide coverage.

Scotland operates its own permitted development order and its own grant scheme through Home Energy Scotland rather than the Boiler Upgrade Scheme. The rules on siting and noise are broadly similar in spirit but not identical in the numbers, so a Scottish homeowner should check with the local council rather than rely on the England technical guidance.

Wales has its own General Permitted Development Order and made its own separate amendment in 2026, so the timeline and the detail differ from England. Northern Ireland runs a fully separate planning system, and permitted development for heat pumps there follows the Northern Ireland order, not the England one.

The practical takeaway is simple. If you are in England, the December 2024 relaxation is directly relevant. If you are elsewhere in the UK, treat this guide as background and confirm the current position with your own planning authority before you order anything.

How to Check Your Own Property in July 2026

The fastest way to confirm your status in July 2026 is to work through a short checklist, then get your MCS installer to run the noise calculation before you sign anything. Here is the sequence I recommend.

  1. Confirm your property type. Is it a house rather than a flat or maisonette? Houses are the main beneficiaries of the December 2024 relaxation.
  2. Check for designations. Search your address on your local council's planning map for conservation area status, listed building status, or an Article 4 direction. Any of these can pull you out of permitted development.
  3. Check the unit volume. Ask your installer to confirm the outdoor unit is 0.6m³ or less.
  4. Get the MCS 020 noise result. This is non-negotiable. The 42 dB(A) figure at the neighbour's window decides whether your siting works.
  5. Consider a Lawful Development Certificate. If you want certainty, or you expect to sell soon, apply to the council for one. It removes doubt for future buyers.

If you would rather not manage this yourself, a good installer handles the whole planning check as part of the survey. Our find an installer tool and the guide on how to find an MCS certified heat pump installer both help you shortlist firms that do this properly. You can also sanity-check whether your home is a strong candidate first using the is my home suitable checklist.

Grants sit alongside all of this. The Boiler Upgrade Scheme, administered by Ofgem, offers 7,500 pounds off an air source heat pump in England and Wales, and it runs entirely separately from the planning question. Our heat pump grant page tracks the current eligibility rules.

A Composite Example Based on Typical UK Homes

The following scenario is an illustrative composite drawn from typical UK installations, not a single named case.

Picture a 1930s semi-detached house on a narrow plot in Sheffield. Under the pre-2024 rules, the only sensible spot for the outdoor unit sat about 0.7 metres from the shared boundary with next door. That fell inside the old 1 metre exclusion, so the owner would have faced a full planning application, a fee, and an eight to thirteen week wait, all for a fairly ordinary installation.

After the December 2024 change, that same position now qualifies as permitted development, because the 1 metre boundary rule no longer applies. The installer still runs the MCS 020 noise calculation, confirms the unit sits below 42 dB(A) at the neighbour's window, and checks the property is not in a conservation area. With those boxes ticked, the job proceeds without any planning application at all. The owner still applies for a Lawful Development Certificate for peace of mind, at a modest fee, and keeps the certificate on file for when they eventually sell.

The lesson is that the December 2024 reform did not remove the conditions that protect neighbours. It removed a blanket geometric rule that was catching sensible installations along with awkward ones.

FAQ

Do I still need to keep my heat pump 1 metre from the boundary in England?

No. The 1 metre boundary condition for air source heat pumps in England was removed on 29 December 2024. A compliant unit can now sit closer to your boundary and still qualify as permitted development, provided it meets the volume, noise, and siting conditions in Part 14 of the General Permitted Development Order.

Can I install two heat pumps under permitted development now?

Yes, in England. The December 2024 change allows a second air source heat pump on the same house to qualify as permitted development, where the earlier wording only covered one. Both units must independently meet the volume and noise conditions.

Does the December 2024 change apply in Scotland and Wales?

No. The change amended the England order only. Scotland, Wales, and Northern Ireland each run their own permitted development regimes. Wales made a separate amendment in 2026, and you should confirm the current position with your own planning authority.

What noise limit applies to my heat pump?

The MCS 020 planning standard sets the test at 42 dB(A) at the nearest neighbouring habitable-room window. Your installer runs this calculation as part of the survey. If the result exceeds the limit, the installation is not permitted development and you would need a full planning application.

Do I need planning permission if I live in a conservation area?

Often yes. Conservation area status keeps tighter controls, and in some streets with an Article 4 direction, permitted development for heat pumps is withdrawn entirely. Check your address on the council planning map before you order equipment.

Is a Lawful Development Certificate worth getting?

It is optional but useful. The certificate formally confirms your installation is permitted development, which removes doubt for future buyers and their solicitors. Many owners apply for one purely to smooth a future sale.

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