Do I need planning permission for air conditioning in Westminster?

The short answer

Usually yes, in Westminster. Much of the borough is covered by conservation areas, where fitting a condenser unit to a street-facing wall needs planning permission. Rear walls and hidden roof spots are often fine.

A condenser unit is the outdoor half of the system — a box about the size of a suitcase. Where it goes decides whether you need permission.

Permitted development rules

For houses, one outdoor unit is normally allowed without permission if it sits more than a metre from the property edge, isn't on a wall facing the road, and meets noise limits. That's called permitted development — work you can do without asking the council.

Flats don't get permitted development rights. If you live in a flat anywhere in Westminster, assume you need permission until your installer confirms otherwise.

Flats and conservation areas

Conservation areas cover most of central Westminster — Marylebone, Mayfair, Soho, Pimlico. In these areas, anything visible from the street usually needs the council's sign-off.

Your installer will look at where the unit can physically go, then advise whether a full application or a lawful development certificate is right.

How to apply in Westminster

Applications go through Westminster City Council's planning portal. Your MCS certified installer usually handles the drawings and submission, or points you to a planning consultant if the case is unusual.

What installers handle for you

MCS certified installers apply for the grant on your behalf, coordinate with your freeholder if you're leasehold, and can prepare the planning paperwork. You sign, they file.