What size air conditioning do you need, and what does it cost?

What this can work out, and what it can’t

A few questions about the room and you get an indicative price band at the end of them. No email address, no phone number, and no callback — the number is on the screen.

Sizing starts with floor area and then adjusts for what the room actually is: a conservatory, a loft room or a kitchen carries more heat than its dimensions suggest, and each of those is one step up in capacity. The bands here come from the same rules, so the number is a real estimate rather than a teaser.

What it cannot see is the building. Where the outdoor unit can go, how the pipework routes to it, whether the noise calculation your permitted development rights depend on passes at your neighbour’s window — those need somebody to look, and they are what the survey is for. Nothing is drilled until you have signed off where it goes.

If you would rather read first: what size unit you actually need, whether you need planning permission, or the published prices.