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Permitted Development Rights for Heat Pumps – Hidden Pitfalls & How To Mitigate Them

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I have worked both in local government and technology/engineering and in this article I take a look at aspects of permitted development rights in relation to heat pumps, identifying some risks to householders.

Those contemplating the installation of a heat pump under Permitted Development, where there is any risk that a current or future neighbour might complain, or who live in an area where the local authority takes a negative or risk-averse attitude towards heat pumps, may wish to take note and consider the mitigating steps described.

Many, possibly most, heat pumps are installed under ‘Permitted Development (PD) Rights,’ national legislation which means that certain types of development can take place without seeking planning permission from the local (planning) authority (LPA)—generally the District/Borough or Unitary Council.

Published advice frequently states simply that most installations of heat pumps can be carried out without planning permission (i.e., under PD). This may be true; however, to qualify as permitted development (and thus not require an application for planning permission), certain requirements must be met. These are set out in full in the legislation which, of course, ‘trumps’ any guidance published by the government, local authorities, or others.

Although the principles are very similar, the requirements differ slightly between the four legal jurisdictions in the UK. This article deals specifically with England; you should check your local rules if you live in Wales, Northern Ireland or Scotland. The links to the relevant legislation for all four parts of the UK are at the end of the article.

The Government planning portal lists the requirements that heat pumps must meet to qualify for permitted development rights in England. At time of writing (July 2024), this is fully consistent with the actual legislation (which has not always been the case). However, given that legislation changes and guidance is often not comprehensive, it is wise always to check back to the source legislation which, fortunately, is (fairly) readily understandable.

Two of the requirements for permitted development which are rarely discussed have, in my opinion, the potential to significantly undermine the value of PD rights.

The ‘Problem’ Requirements and Enforcement

The potentially problematic requirements are specified as ‘conditions’ in the legislation as follows:

“G.3 Development is permitted by Class G subject to the following conditions -

(b) the air source heat pump is, so far as practicable, sited so as to minimise its effect on the external appearance of the building;

(c) the air source heat pump is, so far as practicable, sited so as to minimise its effect on the amenity of the area.”

The difficulties with these particular conditions are:

• They are neither deterministic nor precise, i.e., it is a matter of opinion what constitutes ‘minimised’ and what constitutes ‘practicable’ – for example, does ‘practicable’ include financial considerations as well as purely technical ones, and is a location which would require express planning permission – e.g., for a screen – ‘practicable’?

• ‘Minimise’ is a superlative; the requirement as stated is that the minimum impact be achieved, not just that the impact is sufficiently small, and thus even locations which many would consider perfectly acceptable may not satisfy the condition if it is interpreted strictly.

• Finally (and crucially), the arbiter is the LPA, and since the LPA is also the enforcement authority, it is effectively acting as judge, jury and executioner.

It is quite possible that the original intent of these conditions was to provide for some flexibility and pragmatism; however, there is nothing in the actual wording which ensures that this is the case. To add such wording would not have been difficult (and it is anyway questionable whether these conditions are necessary given the detailed specification of requirements elsewhere); however, the authors of the legislation either thought otherwise or didn’t consider the potential practical issue.

Interestingly, conditions similar to these appear only in planning legislation in relation to a very small number of types of domestic development, namely satellite dishes, CCTV and renewable technologies, yet large extensions, ancillary buildings, and almost anything required for fossil fuel heating (including, for example, tanks for oil storage which can be very unsightly) are permitted without similar constraints. The rationale for this distinction is not known.

If the requirements are not complied with (in the opinion of the LPA), the householder could be subject to enforcement action. There are various ways the LPA can enforce conditions attached to permitted development (or indeed any planning permission), but in each case, the householder could be required to make changes to, remove, or discontinue the use of the installation. Non-compliance with enforcement action is an offense, and, with the route that an LPA is perhaps most likely to take (a ‘breach of condition’ notice), the only route to challenge is through the High Court. Defending a case in the High Court would, in many cases, require the employment of expert witnesses/planning lawyer and so many will effectively have no option but to comply. Enforcement action in relation to heat pumps certainly does occur, and can be brutal, having the potential to deny, during winter, the principal source of domestic heating.

This puts the householder in legal jeopardy for a period of up to 10 years after the installation (after this period enforcement action cannot usually be taken). Potentially the installer is also at risk of being sued if the householder had relied on the advice from the installer in relation to planning law, although many installers will doubtless protect themselves from this by means of a disclaimer in the contract.

Would a Local Authority Actually Do This?

In practice, an LPA is very unlikely to take enforcement action unless there is a positive reason to do so. There are two circumstances where this might be the case.

1. If the Local Authority receives a complaint about noise or visual amenity from a neighbour or a third party (however ill-founded).

If the Local Authority receives a noise complaint (‘statutory nuisance’), which is perhaps the most likely, it has a duty to investigate and, in practice, has the choice to deal with it through environmental protection law or through planning law. Almost certainly, the first action after receiving a complaint will be to contact the owner of the heat pump and to check if planning permission exists. If there is any doubt about the latter, taking action using planning law will generally be easier for the authority because the onus is on the householder to show that they have planning permission, whereas under Environmental Protection law, the onus is on the Local Authority to prove statutory nuisance. The latter is both difficult and rather time-consuming, because the ‘bar’ for statutory nuisance is set quite high.

Thus, the ‘easy way out’ for the Local Authority is to use planning law if they can, to exert pressure on the owner of the heat pump and thus demonstrate to the complainant that they are doing something, without any need to assess whether the complaint has any material merit. There are several reports of local authorities doing just this following a noise complaint.

2. The Local Authority takes a negative, or very risk-averse attitude to heat pumps

Many LPAs appear to be fairly relaxed about heat pumps and/or positively to encourage them, but some seek, wherever possible, to impose much more rigid constraints, especially in respect of noise, than those imposed under PD rights.

As a concrete example, if planning permission is sought from my LPA, it will (according to the information published on its website) usually require that noise pressure from a heat pump is no more than 20dB(A) at the most affected assessment point, if it is in a ‘Small Town or Village’ or 29dB(A) if it is in a ‘Town/City Centre or in most cases within 500m from major roads’. These figures are respectively 17dB and 8dB lower than the limit under permitted development rights and unachievable in many, perhaps the majority, of cases. The local Environmental Health Officer is, incidentally, on record as stating that he believes that the noise requirements under permitted development are too relaxed for much of the area.

Whilst removal of PD rights altogether by the LPA is possible (under an ‘article 4 direction’), this is normally restricted to a limited geographic area. However, it could use the conditions of PD to make it very difficult for anyone to take advantage of the rights and do so retrospectively for up to 10 years. It would only need to do that in a couple of well-publicised cases to ‘frighten off’ most people.

To the best of my knowledge, no local authority has used the conditions in this way described above, but then there aren’t that many heat pump installations yet. As the number of heat pumps increases, local authorities that are not particularly sympathetic to heat pumps, or that are receiving complaints, may look for ways to exert more control even in the case of installations under permitted development or to discourage the latter to reduce the number of complaints it has to deal with.

Mitigating Actions

As stated above, it is very unlikely that enforcement action will be taken unless there is a positive reason to do so, and thus in many instances, householders will rightly conclude that the risk is sufficiently low to be ignored.

If a homeowner is concerned about this risk, there is, fortunately, a way to provide certainty, namely to apply to the local planning authority for a ‘Certificate of Lawful Development’. This requires the LPA to decide in advance whether or not the development proposed falls within PD rights and is thus a mechanism to flush out ‘up front’ whether any of the risks identified above apply. The cost is currently £129, half that of a full planning application. Drawings and calculations, etc. will be needed, and it might be necessary specifically to request confirmation that the conditions have been met to ensure that the LPA covers this in their response. If the certificate is refused, then an appeal (which is free of charge) can be made to the planning inspector.

The risk of this mitigating approach is that it ‘flags’ the development to the LPA and of course, there will be a delay whilst the LPA makes a decision. Householders need to weigh this up against the likelihood of a complaint or another reason why the LPA might decide to take enforcement action.

DIY Installations or Other Installations Under Permitted Development Without MCS

If you are contemplating an installation under Permitted Development without using an MCS contractor (for example a DIY installation, which @justin discusses in his excellent article), it could be argued that similar risks apply. Permitted development rights require that installations conform to ‘the MCS Planning Standards or equivalent standards,’ and the ‘MCS Planning Standards’ (which are written by MCS) expressly require that installations be carried out by an MCS registered contractor to MCS standards. Thus, unless you can successfully argue ‘equivalence,’ only installations carried out by an MCS contractor fall within PD rights. The MCS standards, incidentally, go well beyond noise levels and cover technical requirements which belong (if they belong anywhere) in building regulations, not in planning law.

A local planning authority, ill-equipped to judge the technical detail specified in MCS standards, may well take the risk-averse view that ‘equivalence’ means ‘recognised equivalence.’ At the time of writing, there is no recognised equivalent standard, albeit that an organisation called flexi-orb is said to be working on one. Currently, therefore, an LPA may well conclude that nothing short of MCS will do. An application for a certificate of lawful development could be used to flush this out in advance and thus remove the jeopardy, provided sufficient detail was given in the application so that it was clear that an MCS registered contractor would not be used.


Planning law is meant, for very good reason, to provide a high degree of legal certainty for developers, and permitted development rights for renewable technologies are presumably intended to encourage their use.

For the reasons set out above, the current legislation fails the first test and appears to impose much more stringent requirements on renewable technologies than are imposed on fossil fuel heating. Furthermore, it appears to create something close to a ‘closed shop’ for MCS, which prima facie is anti-competitive, and to have imported into planning legislation (through the ‘MCS Planning Standards’) a large body of mandatory technical detail which, in the opinion of the author, has no place in planning law. The author believes that this is a highly unsatisfactory situation, which introduces unnecessary hurdles to decarbonisation, and needs to be addressed.

That said, it must be reiterated that a local authority is unlikely to take action unless there is a positive reason. So if you are reasonably confident that your neighbors are not going to complain during the 10 years following the installation, and that your LPA is not likely to use its powers in the way described above because it is risk-averse or simply doesn’t agree with the national rules for Permitted Development, then you should not be unduly concerned. However, if you are not confident of these, then you may want to consider applying for a Certificate of Lawful Development.

Appendix – Legislation

Legislation in all four legal jurisdictions of the UK takes the form of an original ‘order’ and several subsequent amendments. In England and Northern Ireland, the text of the order can, at the time of writing, be viewed online as amended by subsequent orders, i.e., it can be displayed ‘up to date.’ Sadly, this is not the case in Wales or Scotland, so it is necessary to read both the original legislation and subsequent amendments to ascertain the current status.


Government guidance appears here:

Northern Ireland:

Wales: as amended by

Government guidance appears here:

Scotland: as amended by

Government guidance appears here:

This topic was modified 2 weeks ago by Mars

Judith, AllyFish and Derek M reacted

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