Which method is more effective (and why) for recirculating air into a room: a) using a fan to blow air out of a window, or b) using a fan to blow air in through the window?

Question

For context, I’ve got a basement room in an old house that isn’t tied in to central air conditioning, and sometimes the air gets a bit stale.

It has a basement window, so I’ll open that up and stick a fan in the window to blow air out, but someone told me that it’s better to have the fan outside and pulling fresh air in.

The room won’t be overpressured as it’s got a big gap under the door, and the fan doesn’t cover the whole window.

In: Physics

Answer 1

I think blowing in is best. If you set the fan to blow out, it may be slightly better at blowing the inside air out, but the replacement air has to come from somewhere. Most likely this replacement air will be pulled from the rest of the basement, or from the house, so it will also be kinda stale. Blowing in from the window gets you air from outside directly into the room, ideally directly at you.