My neighbour's outdoor unit is under my window. What are the rules on noise?

This comes up in search often enough to be worth a thread, and it is one where the honest answer is that this site does not have the whole of it yet.

What is on the site: the unit database lists the published noise figure for each unit, and there is a piece on what a noise figure actually tells you, which is less than most people assume. A figure measured at one metre in a test chamber is not what you hear through a bedroom window at two in the morning.

What is not on the site, and what I would not want to state without checking properly: the enforcement route. Statutory nuisance sits with the local council's environmental health team, and permitted development for these units carries its own noise condition, but the detail of how those two interact is not something I have written up yet.

If you are living with one, what your council actually did is worth posting. That is the sort of thing no specification sheet will tell anybody.

David in Kingston wrote:

This comes up in search often enough to be worth a thread, and it is one where the honest answer is that this site does not have the whole of it yet. What is on the site: the unit database lists the published noise figure for each unit, and there is a piece on what a noise figure actually tells you, which is less than ...

One thing worth separating out, because people tend to run the two together: whether a unit was allowed to be fitted and whether it is too loud now are different questions, answered by different parts of the council, and winning one tells you nothing about the other.

If you are living with one, the useful thing to post is what your council actually did when you contacted them: who you spoke to, what they measured, and how long it took. That is the part no specification sheet covers.