If a heat pump is permitted development, why isn’t air conditioning?

If a heat pump is permitted development, why isn’t air conditioning?

Air conditioning seems to be everywhere in the news at the moment—and for obvious reasons. A few recent enquiries have led me down a planning rabbit hole, and I’ve ended up with a question I’d genuinely be interested to hear views on from the Town Planners (and everyone else!) in my network.

As I understand it, the installation (and replacement or alteration) of a heat pump can be Permitted Development under Schedule 2, Part 14, Class G, allowing:

• up to two external units for a detached house
• one external unit for other houses and flats

Air conditioning, however, isn’t Permitted Development.

Here’s the question…

From a planning perspective, what is the meaningful distinction between the external unit of an air conditioning system and the external unit of a heat pump, assuming both comply with the physical limits of Class G?

As far as I can tell:

• They’re broadly the same size (if anything, many AC units are smaller).
• They produce similar levels of noise.
• They look virtually identical.

If that’s the case, what is the planning harm that distinguishes one from the other?

I suspect we all know the reality. Heat pumps are rightly perceived as a sustainable low-carbon technology, whereas air conditioning is often viewed less favourably. But does that translate into a material planning distinction when the external units are, in practical terms, almost indistinguishable?

It also raises an interesting enforcement question.

I suspect there are already a huge number of external AC units installed across the country without planning permission – I’ve counted well over 100 in my own postcode although, to be fair, they could all be heat pumps!
Unless an installation exceeds the physical limits in Class G, how would a planning authority distinguish between a lawful heat pump and an unlawful AC unit without physically inspecting the equipment itself? And if the planning impacts are otherwise identical, where does that leave the decision-making or enforcement position?

I’m not trying to make a point either way—I honestly don’t know the answer, and at the moment it’s a hypothetical discussion rather than a live issue for my clients.

I’d be really interested to hear from local authority planners, planning consultants and anyone who’s dealt with this in practice. Have you encountered this issue, and if so, how was it approached?

If you would like any planning assistance, the team at Exdell will be happy to help. Get in touch to see how we can best support you.