Derby: 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 Derby whatever the property, because on its own it only cools.

In Derby, the system you choose is a planning decision as much as a comfort one. An air-to-air heat pump on a house qualifies for permitted development because it does both jobs; a unit that only cools is excluded from that route entirely. Conservation-area coverage in Derby is genuinely low (around 5% of EPC-certified homes), so for most addresses an external unit is a lower-friction proposition than in a heritage-dense borough - an honest advantage, not a workaround.

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 Derby flat will usually need both freeholder or managing-agent consent and planning permission.

Only around 4.8% of Derby's properties sit inside a conservation area, a low share by national standards. That means most houses here clear the permitted-development bar for an outdoor unit without extra paperwork - though a flat will typically still need Derby Council to issue planning permission.

100% of the 48 planning applications mentioning air conditioning or other cooling plant that Derby has decided were approved, a figure covering all development types and including 11 householder applications.

The same figures as counts are 48 approved and 0 refused.

A householder-only rate would be the more useful number, and Derby has not yet decided enough of them for one: 11 is below the sample size we publish a percentage from.

One more thing about the method: applications are identified from their own description, so the Derby figures cover applications mentioning cooling equipment and will understate rather than overstate real activity.

Derby has also decided 23 applications mentioning an air-source heat pump, 100% of them approved. That is a separate measure from the cooling figures above, since most air-source installations heat rather than cool and the two sets overlap.

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 Derby sits around 42 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.

None of this is a dealbreaker: councils in Derby approve outdoor units for homes like these all the time. Around 4.8% of local properties sit inside a conservation area, so it is a step to plan for rather than a formality. Being close to a listed building - around 1.6% of homes here sit within 30 metres of one is not the same as your home being listed, and public data can flag conservation status without settling it. This is indicative guidance, not legal advice: confirm the final position with your Local Planning Authority before you install.