Most houses have extract fans fitted to them, mostly in our bathrooms and kitchens. However, we rarely think about which way they are facing. Most commonly they are fitted to the nearest wall, simple.
The UK is one of the windiest countries in the world and so the chances are that the prevailing wind will have a large influence on the effectiveness of the extractor, especially if it is facing west. Anyone who has a west facing extractor will be very aware of the level of noise generated by flapping louvres and also by back draughts and the inability of the fan to clear the room of water vapour. So, if possible fit fans away from the prevailing wind so that they can function properly and quietly.
Fitting fans to the lee sides of a building is not always possible, so what to do then?
There are a couple of solutions, firstly you could fix an in-line back draught shutter system. I haven’t tried these myself, but they are on the market and should provide you with some protection, however if the fan is on and the wind blowing then my money is on the wind winning! One also fears that they too might suffer from acoustic issues.
The system that I have used at home is to replace the louvres with a louvres and hood combo. This has altered how the system works quite dramatically for us. The two bathrooms are much quieter and the fan seems to be more effective.
The basics are that the fan can now work without fighting the wind so much and also that the protection stops the rattling of the louvres as the pressure changes due to the wind are now just coming from below. It also has the advantage of protecting the vent from the rain more.
So it is worth having a think about extractors and how well they are working and what, if anything, can be done to improve their efficacy.