Do You Need Planning Permission for a Heat Pump?

If you’re thinking about an air source heat pump, “will I need planning permission?” is usually one of the first questions that comes up — right after cost and running costs. The good news is that for most homes, the answer is no. But the rules around permitted development, noise limits and listed buildings have shifted in the last year, so it’s worth knowing exactly where you stand before you commit.

The default: permitted development rights

Most detached, semi-detached and terraced houses in England can install an air source heat pump under “permitted development” — meaning you don’t need to apply for planning permission at all, provided the installation meets a few conditions:

• The outdoor unit sits on domestic premises, not on a flat roof more than 15 metres from the boundary
• It’s the only heat pump on the property, or one of a maximum of two following the 2025 reform
• It meets the noise limit at the nearest neighbouring habitable room window

A significant change came into force in 2025: the old rule requiring the unit to sit at least one metre from your property boundary was scrapped, and homes are now permitted to install two heat pumps under permitted development rather than just one. That second point matters increasingly often as more households add air-to-air units alongside a main air-to-water system, or simply need a larger unit for a bigger property.

The noise limit, explained properly

The rule that still applies — and always has — is a noise limit of 42 decibels, measured one metre outside the nearest neighbour’s habitable room window, whichever direction that happens to be. To put that in context, 42dB is quieter than a domestic fridge and well below normal conversation levels.

In practice this is rarely a sticking point. Modern heat pumps, including the Vaillant units we install, typically run at somewhere between 28 and 40dB at the unit itself under normal conditions, comfortably inside the limit once you factor in distance and any screening. Where it can become relevant is on tightly terraced streets with very close boundaries, or where the only sensible mounting position points straight at a neighbour’s bedroom window — cases like these sometimes call for a quieter model, a different mounting position, or acoustic screening.

From 28 May 2026, MCS 020 became the sole certification method accepted as evidence that an installation meets the noise condition for permitted development in England. Older calculation methods are no longer valid for this purpose. In practice this changes nothing for the homeowner — your MCS-accredited installer runs the MCS 020 assessment as part of the survey and design process, and it’s included in your quote. It’s simply the industry tightening up how compliance gets proven.

Where you do need permission

Permitted development doesn’t cover every property. You’ll need to apply for planning permission, or in some cases listed building consent, if:

• Your home is listed (Grade I, Grade II* or Grade II). Listed status removes permitted development rights for external alterations entirely, so any heat pump installation needs listed building consent from your local planning authority, regardless of noise or size.
• You live in a flat, particularly above ground floor — flats generally fall outside permitted development for heat pumps and need a planning application.
• You’re in a conservation area or Article 4 direction area, where councils have withdrawn some permitted development rights — worth checking with your local authority before assuming you’re covered.
• You want more than two heat pumps, or a unit that doesn’t meet the size, position or noise conditions above.

None of this makes a heat pump unavailable in these situations — it just means an extra step. Many conservation area and listed building applications for heat pumps are approved, particularly where the unit is sited discreetly and a qualified installer’s noise assessment is submitted alongside the application.

What this means if you’re planning an install

For the large majority of UK homeowners, the practical answer is still that a heat pump goes in without any planning application, on the same kind of timeline as a boiler replacement — typically one to two days for the installation itself. The main thing worth doing before you commit is a proper site survey: it confirms whether your property is covered by permitted development, checks the noise assessment stacks up for your boundary, and works out the best mounting position before any consent question even arises.

If you’re not sure whether your property is listed, in a conservation area, or otherwise outside permitted development, that’s exactly what a survey is for rather than something to guess at. We offer a free, no-obligation survey that covers the planning position alongside sizing and running cost estimates, so you know exactly what’s involved before deciding anything.