Conservation areas: what actually gets approved

Published 17 Jul 2026 · data: borough planning registers, exact-phrase counts, snapshots 18–22 Jul 2026 · counts measure planning activity, not installations

Live dataset: 15 boroughs measured across the complete 33-borough sweep, 18–22 Jul 2026 snapshots; boroughs failing our data-quality thresholds are shown as unmeasured rather than guessed. Basis note: our decision times run from the date a borough received an application, which is earlier than the validated date councils use in their own statistics — so our waits read slightly longer than official figures, deliberately, because received-to-decided is the wait a real applicant experiences.

Conservation areas are where London’s air-conditioning planning pain concentrates. Kensington & Chelsea — where conservation coverage is among the highest in Britain — generates 3–4× more planning applications mentioning “air conditioning” than comparable boroughs. K&C residents don’t love cooling more than anyone else. In a conservation area, work that would be invisible to the planning system elsewhere needs an application.

What the rules actually say

Permitted development for a heat pump that heats and cools is not abolished in conservation areas — but the unit must not sit on a wall or roof that fronts a highway, and boroughs can remove permitted development rights entirely with an Article 4 direction. Cooling-only units need an application everywhere. (Citations and the May 2025 changes: what the law actually says.)

What the registers show

The headline surprises people: London says yes. Across decided applications mentioning “air conditioning” received since January 2023, approval rates in measured boroughs run from 75.8% (Bromley) to 97.1% (Haringey). Even Kensington & Chelsea — which generates more of these applications than any borough in our dataset, 539 decided in that window — approves 93.4%. The realistic fear is not refusal. It is time.

The wait: typical decision times run 8–13 weeks against the 8-week statutory target — Hillingdon is the fastest measured at ~8 weeks; Camden and H&F run ~12; Bromley and Haringey are slowest at ~13. The tails are the danger: one in ten Camden applications took over a year, and the slowest — a single AC unit with an acoustic enclosure, ref 2019/1359/P — took 45 months, verified against Camden’s own register. (The 9-month patio unit we used to cite, ref 2022/5636/P, turns out to be unremarkable.)
The K&C paradox: conservation coverage makes people apply — triple the application volume of peer boroughs — but doesn’t slow the processing: K&C’s ~10-week median beats Camden’s ~12. The pain is the obligation to apply at all, plus tail risk.
The relabelling shift, borough by borough: “heat pump” filings now outnumber “air conditioning” filings in most boroughs we measure — Camden runs about 2:1 — the same comfort, described in the vocabulary the system favours, and since May 2025 a real legal distinction (units that heat and cool get the permitted-development route; cooling-only doesn’t). The exceptions are K&C and Westminster, where applications still say “air conditioning” — the conservation heartlands haven’t relabelled.

Source: borough planning registers, aggregated via PlanIt · snapshots 18–22 Jul 2026 · counts are planning application activity, not installations · approval = approved/(approved+refused) on normalised statuses, shown only where n≥30

Giving an application its best chance

Rear or side elevation, invisible from the street — visibility from the public realm is the deciding factor in most refusals.
Quietest available unit, with the acoustic report included up front; offer an absorptive screen where a neighbour is close.
Describe the system as what it is, an air-to-air heat pump providing heating and cooling, not “an air conditioner.”
Check for Article 4 directions before assuming any permitted development right.

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