Best if the fan has two blades moving in different directions.
Air exchange will work with a fan blowing in or out only. Leave the louvers around the fan closed, close the room door and air has to escape through the window around the fan.
so that air can flow in and out of different sides of the same window, instead of having to have two windows, one with air flowing in and the other with air flowing out
A window fan changes this a little.
Best if the fan has two blades moving in different directions.
Air exchange will work with a fan blowing in or out only. Leave the louvers around the fan closed, close the room door and air has to escape through the window around the fan.
My room gets very chilly by morning doing this.
Edit: for those you haven’t seen a window fan https://noai.duckduckgo.com/?q=window+fan&rpl=1&ia=images&iax=images
Trying to iimagine a fan with blades in different directions…
Window fans have two sets of fan blades side by side. They can spin in opposite directions.
Why?
so that air can flow in and out of different sides of the same window, instead of having to have two windows, one with air flowing in and the other with air flowing out
Oh, so it’s effectively two independent fans. I misunderstood before.
I too was imagining an overlaid set of counter-rotating blades