Most air source heat pumps in England no longer need a planning application — the 2025 permitted development changes saw to that — but the exceptions still catch people: listed buildings, flats, oversized units and, above all, the MCS 020 noise standard. Answer five questions and this checker tells you where your installation stands.
Heat pump permitted development checker
The checker needs JavaScript enabled. The rules are explained in our heat pumps and permitted development guide.
What changed in 2025
- The 1-metre boundary rule was removed — a unit can now sit close to a neighbour's boundary, provided the noise condition is met.
- The size limit rose from 0.6 m³ to 1.5 m³, covering almost every domestic monobloc unit on the market.
- Detached houses may install up to two air source heat pumps under permitted development.
- MCS 020 stayed — sound at the nearest noise-sensitive neighbour must not exceed 37 dB(A). With the boundary rule gone, this noise assessment is now the key constraint on siting.
Those changes are a big part of why UK heat pump installations keep setting records.
When you still need planning permission
- Listed buildings — PD rights do not apply on or within the curtilage of a listed building; listed building consent may also be needed.
- Flats and maisonettes — treated differently from houses, and often outside PD altogether.
- Units over 1.5 m³, or more units than PD allows.
- Conservation areas — PD can still apply but extra siting restrictions do; check before fixing the location.
- Article 4 directions — councils can withdraw PD rights locally; always worth a check.
- No MCS 020 assessment — without demonstrating the 37 dB(A) standard, the installation cannot rely on PD at all.
Honest limits
This is a screening tool for householder installations in England — it reflects the headline PD conditions, not every siting detail, and Scotland, Wales and Northern Ireland have their own rules. Treat a green result as "likely PD, confirm with your council", not as a legal determination.
How Fortress Associates can help
If your installation needs a full application — or it forms part of a new dwelling or extension — councils will expect the energy case to be made properly. Our automated energy statement service produces a planning-ready statement in minutes, free: Part L 2021 baseline via SAP 10.2, the full Be Lean / Be Clean / Be Green hierarchy, and the London Plan's 35% target with offset calculations for London schemes. Compare your carbon saving first with our heat pump carbon calculator, browse all services or get in touch.
Sources & further reading
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