I hate to not insulate and then have problems with super cold birds. I don't know what to do. haha
I know I am not in 100% the same climate but.....I have kept birds for many many years. When in the country my birds had a horse stall....zero insulation in a metal barn. Zero incidents of frostbite in the 5+ years we were there. We had a 9 day stretch without power due to an ice storm. Lows were -20 and highs were -4 for a solid week of that. No one died or got frostbite. If I had been running heat on the birds they would not have been acclimated properly and that sudden loss due to power down would have been very hard on them.
Here in town we have survived similar temps....although power is more reliable.
Point is properly acclimated birds are a lot tougher than we give them credit for.