Windows are not vents. Windows allow fresh cool breezes in during hot summer months. That's not what you want in winter. You do want ventilation in winter. @aart gave you excellent suggestions for your type of coop. Ventilation needs to be well above the heads of the birds when they are standing (not squatted in sleep) on their highest roost. You want warm moist air to rise and escape. You definitely do not want cold breezes blowing on your birds. Dry and draft free is key. With proper ventilation you should be able to avoid condensation causing chickens to freeze and/or get frostbite.The window was put in door after I took these picture. Another window will be out in above the chicken door. I have 8 chickens. With both windows ope. I still need a vent?