Do you need planning permission for a heat pump?

What are the permitted development rules for a heat pump in England?

Permitted development is planning permission granted nationally for certain small works. For heat pumps it is set out in Class G of the General Permitted Development Order. Meet every limit below and you do not apply to the council at all.

What changed in 2025?

The Town and Country Planning (General Permitted Development) (England) (Amendment) Order 2025 (SI 2025/560) came into force on 29 May 2025. For houses it made four practical changes.

• The rule that a heat pump had to be at least 1 metre from your property boundary was removed.
• The volume limit for the outdoor unit on a house rose from 0.6 to 1.5 cubic metres. For a block of flats it stays at 0.6.
• A detached house can now have two heat pumps rather than one.
• The noise standard became MCS 020(a) specifically, and the words allowing 'equivalent standards' were removed. The old condition that a heat pump be used solely for heating was replaced with a rule that it must not be used solely for cooling.

A transitional period for installations under the old rules ended on 28 May 2026, so every new installation must meet the current version.

What is the MCS 020(a) noise check?

MCS 020(a) is a sound calculation your installer does before fitting. From the manufacturer's sound data, the distance and any walls or fences in between, it predicts the noise 1 metre outside the centre of each door or window to a neighbour's habitable room (bedrooms and living rooms, not bathrooms, halls or utility rooms).

The predicted level must be no more than 37 dB (LAeq, 5 minutes) at every one of those points, and the installer must give you a copy of the completed calculation. If a spot fails, a different position, a quieter unit or a barrier may fix it. If nothing does, you need to apply for planning permission.

When do you need planning permission or other consent?

• Listed buildings. No permitted development on a listed building or within its grounds. You need planning permission, and possibly listed building consent, a separate application.
• Conservation areas and World Heritage Sites. The unit must not go on a wall or roof fronting a highway, or nearer to a bordering road than the house itself. The back, or a side wall away from the road, can still qualify.
• Scheduled monuments. No permitted development on a site designated as one.
• Article 4 directions and planning conditions. A council can withdraw permitted development rights across a defined area, and some homes lost certain rights through a condition on their original planning permission.
• Anything outside the limits above, such as a failed noise check or a second unit on a semi or terrace.

If your case is borderline, you can apply to the council for a lawful development certificate. It is optional, but once granted the proposed work is presumed lawful, which gives you certainty before work starts.

What about flats and blocks of flats?

Class G does cover blocks of flats, but more tightly than houses. Only one heat pump is permitted development on or within the grounds of the whole block, and its outdoor unit must not exceed 0.6 cubic metres. The Planning Portal notes the rights apply to buildings made up wholly of flats, so a block with shops on the ground floor falls outside them.

So the first flat owner to fit one uses up the block's allowance, and any later one needs planning permission. If you are a leaseholder, your lease may also require the freeholder's consent for anything fixed to an outside wall or placed in shared grounds.

Live in London? How do conservation areas and Article 4 directions affect you?

A conservation area is a part of a borough the council has designated for its special architectural or historic interest. An Article 4 direction is a separate tool that lets a council withdraw specified permitted development rights across a defined area, based on evidence. Each direction lists the specific rights it removes.

Your council's planning pages usually map its conservation areas and list its Article 4 directions, and the planning department can confirm whether either affects your address. Do this before you choose a position for the unit, because it can decide whether the front, side or back of the house is available.

What about Wales and Scotland?

Wales updated its rules on 1 June 2026. Welsh Government guidance now closely mirrors England: 1.5 cubic metres, one unit (two on a detached house), MCS 020(a), no pitched roofs or listed buildings, the same conservation area highway rules, and no boundary distance.

Scotland's rules (Class 6H) differ. The Scottish Government's 2024 circular allows one unit per dwelling, protruding no more than 1 metre from the wall, only on the rear elevation at ground floor level in a conservation area, and not in World Heritage Sites or the grounds of listed buildings.

A practical checklist, and what to ask your installer

1. Check whether your home is listed, and whether it sits in a conservation area, a World Heritage Site or an Article 4 area. Your council can confirm all three.
2. If you are in a flat, find out whether the block already has a heat pump, and read your lease on alterations to outside walls.
3. Choose a ground-level position, ideally at the side or back of the house and away from a road.
4. Ask your installer for the completed MCS 020(a) calculation for that exact position.
5. If anything is unclear, get a lawful development certificate or apply for planning permission before work starts.

• Which neighbouring doors and windows did you assess, and what was the result at each?
• Is this position permitted development, or does it need an application? Who submits it, and is that in the price?
• If that spot fails, what are the alternatives, and do they change the cost?

Ask for the noise calculation at survey, not after. For the price, see our guide to what a heat pump costs in 2026 and our four-question grant checker are the next steps, or see how we install air source heat pumps. If your case is not clear-cut, ask us to look at it.

Common questions