It's not that we're testing how cold our hens can take it, it's that for most people here--obvs. not the people in Manitoba, or Anchorage, or anywhere else it drops below -20 and stays there for the winter--it rarely gets lower than 10 below and the hens will be fine. For most animals, they are healthier if they have more ventilation and the barn isn't heated. We don't heat horse barns, or dog houses, or cattle barns, or pig barns either. In fact, closing up a horse barn or cattle barn tightly enough to heat it is a really good way to cause respiratory problems. The animals are in and out of the barn during the day and it's not good for them to go from a warm to a cold environment and back again. So we keep them out of the wind, we make sure that the area they live is insulated and well bedded and dry, and that's the best way to care for them. We're not sitting here laughing about what Iron Chickens we have--we know that making our hens dependent on supplementary heat in our environment will not be doing them any favors. If the temperature dipped below -20 at my place, yes, I'd hang a heat lamp above the perches to bring the temp up a couple of degrees. But for most winters here, we only get to -25 with wind chill, which is not a factor in my hen house.