AC in a flat when the freeholder is the problem
Published 17 Jul 2026 · legal points cited at /guides/what-the-law-actually-says.html
You own the inside of the flat. Someone else controls the outside walls. That's the whole problem with air conditioning in London, and no planning-law good news changes it: planning permission and freeholder consent are separate locks, and you need both keys.
Route 1 — Ask properly (most people ask badly)
Freeholder refusals are often refusals of a vague ask: “can I put in air con?” invites “no” because it hands the freeholder all the risk and none of the information. A specific ask changes the odds: a named heat-pump unit that heats and cools; the MCS 020(a) noise calculation offered up front; an insured installer; agreed making-good; and the planning position explained (since May 2025 one such unit on a wholly residential block can be permitted development — with a one-per-block limit worth asking about, since if the slot is free your building may want to decide who gets it deliberately).
Our checker generates this letter for you, pre-filled with the right questions.
Route 2 — The monobloc conversation
If the objection is the external box — and it usually is — a monobloc unit removes it. Everything sits inside the flat; two ~16–20cm vent grilles are all that shows outside. You still need consent to drill the structure, but “no external unit, two neat grilles, professional install” is a far easier yes. R290 (propane) versions contain no F-gas, so no F-gas-certified engineer is legally required. Honest trade-offs: one room per unit, lower efficiency than a split, and the compressor lives in the room — check the sound figure if it is for a bedroom.
Route 3 — Portable, with your eyes open
No consent needed at all. But read the single-hose problem before buying: most UK portables underperform their box rating in a way US law would force them to disclose and UK law does not.
If you rent
Everything above applies, with your landlord in the freeholder’s chair — and one advantage: a fixed unit adds value to their asset, which the letter makes explicit.