Replying to
@leitzke@hachyderm.io @DJGummikuh@mastodon.social @0xabad1dea@infosec.exchange
Turn the fan. The fan pulling cool air in is trying to push air into a room already full of air. Also since I assume that your fan is not mounted well outside the window it's mostly stirring the warm air it's sitting in, hoping to "grab" some of that cool outside air in the process.
If you turn it, you push the hot air out. Put the fan about half a meter inside so it sits in the hot air and blows it out the window. The resulting vacuum will be filled from the outside - works best if you have a second window open