Do I need planning permission for a heat pump?

When does a heat pump need planning permission?

Only when the installation breaks the permitted development conditions, or when the building itself is protected. In England, permission is always required within the curtilage of a listed building or on a scheduled monument, and conservation areas carry extra siting restrictions. Everywhere else, a normal wall-mounted or ground-mounted outdoor unit is a notification exercise, not an application.

Ground source and water source systems are simpler still, because there is no visible outdoor unit — but the drilling or excavation may need a separate groundwater or environmental permit.

What are the permitted development conditions in England?

Two points catch people out. The old requirement to keep the unit one metre from the property boundary in England was removed, so a unit may sit close to a neighbour's fence — but the noise calculation still has to pass, which in practice often re-imposes a distance. And since 28 May 2026, MCS 020(a) has been the only certification route accepted for permitted development in England, so quotes prepared against older noise standards need re-checking.

What noise limit must the installation meet?

MCS 020 caps the calculated sound pressure at 42 dB(A) at the assessment position: a point one metre outside the centre of any door or window serving a habitable room of a neighbouring property, measured perpendicular to that opening. The standard assumes a background level of 40 dB(A). A habitable room is a kitchen, living room or bedroom; bathrooms, halls, landings and utility rooms do not count.

The installer performs this calculation before installation, starting from the unit's declared sound power level and correcting for distance, reflective surfaces and barriers. Two identical heat pumps can pass in one position and fail two metres away, which is why siting and planning are the same conversation — see how loud is a heat pump? for what the decibel figures actually mean in a garden.

What about the rest of Europe?

Each country regulates the same two things — how the unit looks and how loud it is — through different instruments.

• Germany: building permission is generally not required, but the Landesbauordnung of each Land sets boundary distances (several Länder have dropped a fixed minimum for units under about 2 m high, while others retain 2.5–3 m), and TA Lärm sets the noise immission limits: 55 dB(A) by day and 40 dB(A) at night in a general residential area, assessed 0.5 m outside the neighbour's open window.
• France: no permit for a standard installation, though a déclaration préalable is needed where the work changes the external appearance of the building. Noise is governed by the Code de la santé publique, which works on emergence above background rather than an absolute limit: 5 dB(A) by day and 3 dB(A) at night.
• Scotland, Wales and Northern Ireland each run their own version of permitted development with different boundary distances and noise tests; check the current official guidance for your nation before fixing a position.

What if permitted development does not apply?

You submit a householder planning application, normally supported by a noise impact assessment prepared to BS 4142 by an acoustic consultant rather than the MCS 020 spreadsheet. Expect the authority to look at three things: visibility from the street, the assessed noise level at the nearest neighbour, and whether an acoustic screen or a different position would resolve the objection. An Article 4 direction can also remove permitted development rights from a whole street, most often in conservation areas.

As a heat pump manufacturer, Solimpeks sees the same pattern repeatedly: the noise calculation is run after the position has been chosen, when it should be the thing that chooses the position.

Practical mitigations that usually satisfy a case officer are a low-sound-power unit selected on its declared figure, a position away from party boundaries and bedroom windows, anti-vibration mounts, and an acoustic barrier that breaks line of sight without obstructing airflow. Choosing a low-sound-power unit at the design stage is far cheaper than screening a loud one afterwards, so compare the declared sound power level of every quoted machine before you compare anything else.