I'm in NS, and currently have 6 9 week old chicks that hatched under a broody and have lived without any other form of heat. Also 12 more that don't have a mom and are under a brooder lamp in their own area of the barn, with 6 more bantam Brahma and Mille Fleur chicks in my aviary in my house. (10 X 2 X 8, houses a couple canaries and my tiny chicks.)
I do know I won't EVER intensionally hatch any more chicks in winter, as it's too hard on my nerves-I worry incessantly about the chicks in the barn, though everyone is doing well. Temps haven't been bad yet,nothing below zero, and we currently have not one drop of snow, but that will change.
If you have a broody, it's SO much easier- when they are cold, they'll run to Mom. She teaches them the rules of the road, and it's just so much easier on everyone.
Can't remember who said it- maybe robb or CJR? mentioned that if you have chickens in heated barn and you lose your power- you could have serious problems. Much better if they are used to colder temperatures, but that doesn't work well with chicks, who need to be brooded at the right temperature...
Then there's the 6 in the house, who think I'm the Mom. They dance around peeping when they hear me, fly up when I open the door, & roost on my arm, they really don't think they are chickens. Sweet, yes- but not everyone has the benefit of an aviary and 5 tonnes of sawdust at their disposal.
That's been my experience so far, it's been VERY intersting and educational, but not something I plan on repeating next year, having learned my lesson.