Westminster: air conditioning planning permission

Since 2025-05-29, England's permitted-development rules let a house fit an air-to-air heat pump - which heats as well as cools - without a planning application in many cases, within set size, siting and noise limits. A cooling-only air conditioning unit does not get that route and needs a full planning application in Westminster whatever the property, because on its own it only cools.

Picking a system in Westminster therefore decides your planning path as much as your comfort. A unit that heats and cools opens up the permitted-development route on a house; one that only cools never does. With around 65% of Westminster's EPC-certified stock inside a conservation area (Regent's Park, Maida Vale, Queens Park Estate among them), confirming the exact boundary before you site an outdoor unit is the single most valuable planning step to take here.

Flats are the sharpest exception here as everywhere in England: the permitted-development right for an outdoor unit sits with the house, not the flat, so a Westminster flat will usually need both freeholder or managing-agent consent and planning permission.

Westminster carries a lot of conservation-area coverage: around 64.9% of its properties sit inside one, including areas such as Regent's Park, Maida Vale and Queens Park Estate. Inside those boundaries, the permitted-development route that lets a house fit an outdoor unit is tighter or removed entirely, so a unit on a front or side elevation will usually need planning permission from the London Borough of Westminster.

Westminster has decided 271 planning applications mentioning air conditioning or other cooling plant across all development types, 116 of them householder applications, and approved 92.3% of that 271.

Put as counts: 250 went through, 21 did not.

Householder applications alone tell a slightly different story, and they are the ones that resemble your case: 92.2% of the 116 were approved.

These are applications whose own description names cooling equipment. An application that installed the same kit but described it as external plant is not in the Westminster count.

A different question, kept separate on purpose: 90.8% of the 87 applications mentioning an air-source heat pump that Westminster has decided were approved. Air-source usually means a heating scheme, not a cooling one, and an application can sit in both sets, so the two figures are never summed or averaged.

What actually gets refused, and what councils attach when they approve, is a national picture rather than a local one at the volume of officer reasoning currently published. We set both out with their sample sizes: why cooling applications get refused and the conditions councils attach.

You can also compare what each council decides, where enough decisions exist to publish a figure.

Background noise in Westminster sits around 49 dB across the property types we profile during the day, which is the level any outdoor unit has to live inside. A machine that is inaudible on a busy street can be the dominant sound in a still garden, so the local baseline changes the answer.

That makes placement the thing to get right: distance from a neighbour's window, and distance from the boundary, do more for an application than the specification of the unit itself.

Nothing here is a dealbreaker. Westminster's council approves outdoor units for homes like these routinely. Conservation-area coverage locally runs at around 64.9%, which makes this worth planning for rather than assuming. Proximity to a listed building - around 28% of homes here sit within 30 metres of one does not mean your own home is listed, and public data can flag a conservation-area question without answering it. Treat this as indicative guidance, not legal advice, and confirm the final position with your Local Planning Authority before installing.