Extractor fan in existing toilet room

An extractor fan is not essential but is much more efficient than opening the window. The fan will take most of the warm damp air out, whereas a open window let's in cold air which causes more condensation

Hi, If your bathroom has an openable window, it does not require an extractor fan to meet building regulations. However, you might still want to install one if you are thinking of the long term, for the following benefits: • To reduce condensation. We’ve all got out of a hot shower or bath and had to wade through the fog to find our towel. • To prevent mould. That condensation mentioned in the point above, well it can lead to a worse problem: mould. Proper ventilation helps stop it from forming. • To extend the life of your bathroom. Condensation and mould both contribute to damage to your fixtures and fittings, not to mention your tiling and grout. An extractor fan is a great line of defence against this. • To keep odours away. Finally, all that damp, stale air can lead to unpleasant smells in your bathroom. A fan helps keep your air nice and fresh.

Ideally yes you would want an extstractor fan in this room not essential if you have the window open when the showers on

Yes you would it will help povent mould and stuff like that happing as much. Also I would more the window due to it losing the seals

It’s good practice (if it’s possible) to install an extractor fan, even with an openable window, as it extracts the moody air from the room. This can escape from an open window too, but the cool air coming in through the window can cause more condensation as it cools the warm air in the room