London’s housing stock is unusually varied for a single city — Georgian terraces, Victorian conversions, 1930s semis and glass-fronted new builds all sit within a few miles of each other, and each brings different air conditioning considerations.
The biggest factor most homeowners underestimate is planning permission. Under Permitted Development Rights, most homes can install an external condenser unit without formal planning consent, provided it sits below a certain size and isn’t mounted on a wall or roof facing a highway. That changes in conservation areas, on listed buildings, and in some flats where the freeholder’s consent is needed regardless of council rules — and London has more conservation areas than any other UK city, so it’s always worth checking before booking an installer.
Victorian and Edwardian terraces tend to have solid brick walls, which make pipe runs between indoor and outdoor units straightforward but limit where a condenser can sit without becoming a visible eyesore on a period façade. New-build flats often have the opposite problem: well-insulated but with strict management-company rules on where units can be fixed, and sometimes no suitable outdoor space at all, which is where a portable or through-wall unit becomes the practical choice.
Running costs vary with system efficiency and how much of the home is cooled. A single well-sized split system cooling one or two rooms typically costs a few pounds a day to run during a heatwave; cooling an entire London terrace with a multi-split system costs proportionally more, which is why getting the sizing right at the quote stage — rather than after installation — makes the biggest difference to ongoing bills.
Use the calculator further down this page to get a rough sense of the unit size your room needs, then compare quotes from installers who work regularly in your specific borough, since local knowledge of conservation rules and property types speeds up the process considerably.