I'm trying to set up a room which I know will be pretty cold starting in the next few weeks here. It's my understanding that a carbon filter will filter the air being passed through it, exhausting scent-free air. I plan on simply running a space heater to keep the room warm. That all being said, what I want to do is have an intake fan and duct shooting the outside air into the room, then have an exhaust duct with a carbon filter on the other side. I was wondering if I could just exhaust the air flowing through the c filter right back into the room to avoid losing so much heat, as the cold air being sent in from outside will surely keep the room too cold if I keep replacing the air every few minutes? I have a few thoughts on why this could cause problems but what are your thoughts?