Wow! Those are crazy temperatures! I get it now, you setup is very well designed, sound slick you care a lot about your animals.I should clarify, seems I explained it badly.
There is no heat on the ducks. They are in a shared cabin, and their space is above the others, so it is naturally warmer than those that are on the floor. The chickens have a heat lamp, which is under where the ducks are, but the ducks don't choose to make a bed above it. The duck floor is 3/4" plywood, a plastic layer made of old feed bags so I can clean it, and then some mismatched tiles that are not glued so I can remove them to clean and then the bedding. There is no way that the heat lamp pointed down at the chickens is heating all the way through that. But, it is just nicer than being on the floor.
fire: Short of building a campfire inside the house it is not possible to burn that building. Although the outside is wood, the inside walls are recycled sheet metal from an old barn roof (I guess tin, I don't know anything about metal). Under the metal is insulation that is wool made from rock and it is the highest fire-rated insulation available (similar to the pink wool, which is made from fiberglass, except that this is made from rock. Unlike the fiberglass, this is not toxic and does not get into your eyes/lungs/cut your skin, and it is more fireproof). There is a vapour barrier between the metal and the insulation, so no little beeks can peck at it. (not that they could peck through metal, but no water/moisture can infiltrate either). The floor is mismatch ceramic tiles that are set in thin concrete.
temperatures: this is (so far) the warmest winter on record, my normal winter temperatures are down to -40F, so the building is made for that. Normal day temperatures will be highs of -13F lows to -26F in a week or two. Nights will be -31F to -40F. After mid-Jan winter will arrive, it always does. It will last until April, spring is late May.
The chickens I adopted at 20weeks and they were raised in one of those factory places where they never go outside, don't even have a window, and temperatures are always the same, and they are descendants of chickens raised in that condition for many many generations. They are not made for the cold, but, god bless them, they go outside every day, for as long as they are able to stand it, no matter how cold. I have a little heat light for them at night, and they cuddle around it. It is 175W and it has 2 settings (off-low-high) I assume High is 175, but I don't know where Low lands on the scale (half-way?). I leave it on low (so far), unless it is so cold they are clearly uncomfortable, then I click it to high. This is their first winter: frostbite is real, and it can cost you toes or limbs. Some of them have little nips of frostbite already on their combs and that is never going to heal. I know from local people that chicken toes do die from frostbite.
My grandparents (and all those I know of in this area), before the world of lightbulbs kept their hens in the barn during the winter. The heat from the animals keeps the indoors warm enough that there is steam rising from the 'stuff' on the floor. The floor is slightly below ground level to keep it warmer, and they pile things like stay and hay between walls and animals. It is pretty hot in there with all cows/horses/whatever. No one would have left them in an uninsulated building in those temperatures. Bare in mind that the humidity in this area is high, so the cold is even more painful than in the dryer areas like the prairies.
(back to now), the door to the house is open during the day so that the turkey can come in and go out all day long. That means the house inside is the temperature outside less the windchill, so the ducks staying inside is not like being in the people house. Today was only -16F and sunny, so I tried to bring them outside, they walked back to the fence and cried to be brought back inside. I left them out maybe 3/4 of an hour and one of them shivered violently when I put her back in the bed. She is fine now, but she is not happy out of the building. I took them outside because I know this is the warmest day in the coming week, so it was my best shot at fresh air and walking outside. Other than bath-time, they are going to be indoors for several days.
power outages: obviously we have a generator, our pipes would explode if there were no heat, so plugging in the hens is easy. But it would take a while for that building to cool off, and the heat from the lamp is not that intense that they would die if it went out for an hour or two. They would complain to me the next day, but no one would be hurt.