I would put a small window in the back of the coop so you can get ventilation, if you need it.
I am a big believer on giving my chicks and older birds more then enough air. I think they do better when there is air moving, even if it is warm air. I put a fan in the brooder room during the summer, while still running brooder lights during some days.
I never let my chicks get over 95 degrees in the brooder room and it usually is around 70 when they are about 4-5 wks old.
It is not very cold down here right now and I have everyone outside in pens during the day. Since the sun is shining and it is about 72. But the windows are open in my brooder room and I have a small fan moving the air through it, though no one is in there. I feel fresh air cures all ailments! Tonight I will close the windows, cut off the fan and only run a 60 wt light. It is supposed to be about 40 tonight and I think that is fine for them.