We live in Oregon. We are finishing our coop (converted and elevated 3x3 dog house with attached run) this week. I've asked my coop contractor (i.e. DH) to put ventilation holes (1-1/2") around the top of coop. But if we do this, the girls will lose the heat in the winter. What are some alternatives? And, how do we balance ventilation? During the winter months, is ventilation as important? Thanks, in advanced.