Hello this is my first time posting. I have 5 chickens. I had 6 but the big old bear got one. : ( ! I am in the mountains tops of the Catskills. They are laying great and some are laying Jumbo eggs here and there. One Golden Comet, named Star.Two Vermont Reds. Big Red & Little Red And two Black Astrolobes. Mid & Night : ) . Who knew I love these chickens so much. Anyways we have a red light bulb in the coop. I hear they don't need any heat but is there a limit of how cold it gets or for how long it stays cold. We are now insulating the coop and there are no drafts and its ventilated at the top of the coop. How big should that vent be as not to make it too cold ? I do know it seems the hot weather effected them more than the cold so far. My girls are spoiled.