Do you need planning permission for a heat pump?

By Richard Smith, Managing Director, Smith's Heating Services

It's the question we're asked more than almost any other: "Richard, before I get excited about a heat pump — am I going to be tangled up in planning permission for months?" It's a fair worry. The good news, and I'll be straight with you, is that for most homes in and around High Wycombe, the answer is no. A heat pump is usually treated as "permitted development," which is the planning system's way of saying go ahead, you don't need to ask.

But "most" isn't "all," so let me walk you through it honestly.

What "permitted development" actually means

The Government sets out rules — under what's called Class G of the planning regulations — that let you install an air source heat pump without a planning application, as long as you tick a handful of boxes. And here's the genuinely good news: those rules were relaxed on 29 May 2025, making it easier than ever.

Your permitted-development checklist

For a typical house, you're fine without planning permission if all of these are true:

• Size: the outdoor unit (including its casing) is no bigger than 1.5 cubic metres — that's nearly three times the old limit, so it covers practically every domestic heat pump on the market.
• Boundary: there's now no minimum distance from your boundary. The old "must be 1 metre from the fence" rule was scrapped in May 2025 — a real help on smaller plots.
• Position: it's not on a pitched roof, and if it sits on a flat roof it's at least 1 metre from the edge. On most installs it simply stands on the ground at the side or rear.
• Front of the house: on the front wall facing the road there are restrictions — rear or side siting keeps life simple.
• Noise: the installation meets the MCS noise standard (MCS 020) — a calculated limit of about 37 decibels at your neighbour's nearest window. As an MCS-certified firm, we do this calculation as standard.
• It's removed if you ever stop needing it.

Hit all of those, and you don't need to ask anyone's permission.

When you DO need planning permission

I'd be doing you a disservice not to flag the exceptions. You'll need a full application if your home is:

• Listed (and you'll also need listed building consent);
• in a conservation area or World Heritage Site and the unit would face a highway;
• covered by an Article 4 Direction (where the council has removed permitted-development rights);
• a flat or maisonette (tighter limits — and check your lease); or
• the install breaks any of the size or siting limits above.

If you're near Hughenden, the Hambleden valley or one of our lovely conservation areas, just ask us — we check this for every survey, and for High Wycombe homes the local planning authority is Buckinghamshire Council.

Can I have two units — a heat pump and air conditioning?

This is where the 2025 changes really help, and it's worth getting right. Historically, permitted development allowed only one heat pump. Now:

• If you live in a detached house, you can have two units under permitted development — for example, an air source heat pump for your heating plus an air-to-air (cooling) unit for those increasingly warm summers.
• If you're in a semi-detached, terraced house or flat, permitted development still allows only one unit. A second usually means a planning application.

One honest caveat: a unit used purely for cooling (pure air conditioning, with no heating) isn't covered by these heat-pump rules and would need permission. A proper air-to-air heat pump that both heats and cools is fine within the limits above. If you're weighing up both, our air conditioning configurator and a quick chat will get you to the right answer.

A quick word on Scotland and Wales

These relaxed rules are England only. Wales keeps a 3-metre boundary rule and a 1 m³ size limit; Scotland generally requires the unit to be hidden from the public road. Not relevant for our High Wycombe customers, but worth knowing if you've a place elsewhere.

Let us take the worry off your plate

Ninety-something times out of a hundred, planning permission simply isn't an issue — and on the rare occasions it is, we'll spot it early and guide you through it. There's no guesswork on our watch.

Book a free, no-obligation survey and we'll confirm exactly where you stand, size the right system for your home, and handle the MCS paperwork for you. Want a head start? Try our instant price estimate or see what a heat pump could cost to run. Then give the Smith's team a call — we'd love to help you get warm, efficient and worry-free.

— Richard

This guide is general information, not formal planning advice, and the rules can change — always confirm your own situation with us or Buckinghamshire Council before installing. Rules current as at June 2026 (GPDO 2015 Class G as amended by SI 2025/560; Planning Portal; MCS).