Thanks for the reply, yes I could leave the door open, and I do need to check the temp during the day. I'm in Texas and I would imagine it is pretty hot in the middle of the day inside. Having said that I have gone in mid day and it was not melting temp inside, though I did not take the temp. No vent on the roof of the building, and other than the garage door, one door and one window. I guess I could hang a fan to move air inside the building. Yes, in the winter all bets are off, I know better than to crank up my furnace in a 3 sides closed area.