The heat/cold issue seems to be a concern for a lot of us-this is my first winter with chickens, I have 4 pullets that are 18 weeks old- barred rocks, a partridge plymouth and a rhode island red. Our temps this year in NW Ohio have been cold (20's and teens and night, upper 20's to mid 30's during the day, lots of wind). I bought a prefabbed coop this summer - not huge but big enough for them. I have it full of pine shavings and sand and I have a heat lamp secured that I leave on during the day with their coop door open (if the temps are 30's or below). At night, I close them in and the heat lamp goes off. THe coop is also wrapped with a plastic tarp because I'm not convinced that it's draft proof or that it's water proof since we didn't build it ourselves. I do keep the vents on top open for circulation. The girls do very well. They are predicting temps for us next week in the single digits with -0 windchills. I am not sure whether I'll keep the heat source on all night or not at this point but will see how they do. For sure, they do not like wind. I've only had to close them in during the day once due to a snow storm. What i've learned so far is that they probably don't need heat during the day, but I know they enjoy the warmth especially when it's windy and colder. So, they get heat during the day. If it's going to be single digits at night and bitterly cold, I'll leave their heat on a lot longer at night and if they are resting and roosting, i'll leave it on, if they're restless and not roosting, i'll turn it off. If the seem stressed the next morning after whatever I did, i'll do it differently the next day. I think we, myself included, make it harder than it needs to be. LOL