How can I re-use a hole in wall for ventilation?

Question

I'm renovating my bedroom and found that there's a hole in the wall beneath the wallpaper. It was plugged, but the stuff in it was old and crappy, so I took it out. Now I've got a 20x20cm (~7.9x7.9in) square hole in my wall that goes to the outside.

The simple solution would be to simply fill it with spray foam and be done with it, but I was wondering if maybe I could use it for additional ventilation. God knows it gets hot and stuffy in the summer. If I had an air conditioner, it'd be a perfect hole for the exhaust pipe, but I don't so...

Anyways, if I do keep it for ventilation, I'd also need to add some kind of door to it because I don't want more cold to come in the winter. I'd probably use a fan for the summer. I haven't seen anything like that though, nor do I know where to look. The local home improvement store employees were also at a loss.

Does anyone have any ideas?

Answer 1

I realize that this is a U.S. reference, but you may be able to find a wall exhaust fan locally similar to this.

You need to find a unit that is intended for exposure to the outdoors. Also you may need a cover in the colder months if the unit you find does not have a self closing louver. The one depicted does.

If you use 110 voltage and 60cycles, you may be able to order something like this from the U.S. Otherwise, be sure that it matches your local electric supply.