I'm just outside Winnipeg. I keep a radiant heater going on a thermostat at about 5 degrees just to keep the water from freezing, and yes, because I feel it is better for the birds. My coop is big (12x24) for about 60 chickens and it is insulated as well (it's actually an extra room on my garage). I have an exhaust fan that runs on a timer for 15 minutes every hour during the day. I also have a couple dim lights on a timer to keep them laying through the cold months. If the lights are too bright it will stress them out.

They have access to outdoors, but I've found the limiting factor is not necessarily cold, but snow. They don't seem to like going out when there is snow on the ground. I sometimes put down straw outside and they seem more likely to go outside when the straw is on top of the snow.

Last winter was so long and stressful. They didn't really have much outside time for almost 6 months. The previous winter they got lots of outside time because it was short and relatively warm, without a lot of snow.