Awesome pic! I asked Nan Bradshaw about ventilation when she was giving her talk on animal husbandry, I've always been perplexed by the 'plenty of ventilation, but no drafts' rule. The statements seem to contradict each other.
She said that ideally, the air flow comes in the coop at floor level on one side, and exits through the other side at roof level, thereby clearing stagnant air. Position roosts out of the direct air flow to avoid drafts on the birds.
I don't know how much sense this makes, she had a diagram that was very helpful.
That does make sense blarney thanks. However I won't be able to leave the pop door open at night as silkie says since there are many predators in my area. I've never seen anyone with a low window though either.