Well, thats depends on quite a few things. Size of coop....temps...how many chickens....breed??
I started with RIR/mix. Last winter was thier first winter. They have a large coop, and it is draft free. I piled the straw in pretty thick..so they could snuggle down in it if they wanted. Also...we didnt clean the poo, just covered it with more straw. It makes a compost sorta, and stays warm. Being winter, no smell. For the roost...we made sure they were wide and flat...so they could not wrap thier toes around them. This keps them from getting too cold. They can lay down on the roost, and keep thier toes warm.
If it got too cold, I hooked up a heat lamp. Just to take the chill off. All made it through fine...no frost bite..and layed eggs all winter long!
For the Banty Cochin Frizzles....they had a heat lamp all winter.