I need an air current in this room, even when the sun shines directly into it.
I was thinking covering the hopper window with either paper or reflective foil and leaving it a bit open, but I don’t know if this is a stupid idea.
A closed window means an unlivable room.
Outside is better, but inside is often a lot easier and almost as effective. Most glass blocks IR (heat). If you reflect it back out before it gets converted, it will exit fine. In practice it’s a few % difference, depending on the foil.