You need Chanteclers... ;^) Mine are in a draughty old bank barn. THey get fresh water every morning, but as for cold, they're on their own. I try to block the really bad draughts, but it's up to them to stay warm. So far they've come through.
The best thing about chanties is that they don't have a comb to freeze. I had a couple of Buff cochins, their combs would get black in the winter.

I would love to have Chanteclers. Maybe I will buy some eggs next spring.

I live in the Rockies, with chickens, they are in an insulated house. I have a heat lamp to provide them with enough hours of light so they will lay, it also keeps them warm.I turn the light on just before dusk and close them up, after a few hours I unplug the light so the house keeps warm for the rest of the night and they can sleep, it also keeps their water from freezing.Generally the colder the weather the longer I leave the light on, when its -30C the heat lamp is on 24/7.I wouldn't recommend leaving them no heat in the bitter cold, they can freeze to death too.If you think all the warm air is going out the ventiation hole then probably best to close it up a bit. Best of luck

It has warmed up some here now and is actually raining on our 3' of snow. I think I will close up the ventilation window when it drops to below 0 F. I don't have a heat lamp but I do have a heating pad under the waterer to keep it thawed. I will have to think about what to do when and if the temps get really cold this winter.

We use a heat lamp (directly over the waterer) when it is really cold. Our hens are in an insulated coop. In January when it gets -30 we dont let the hens outside (they are dumb enough to try ; ) !) and sometimes even with the heat lamp the water will freeze.
runningtrails, the heating pad is an idea I will have to try! Usually the hens will snuggle into the deep hay on the floor if it's very cold. Have had good luck so far, and did do a chicken coop 'reno' this spring replaced some of the insulation and filled up a few cracks in the corners with spray foam to keep out the drafts.

Some good ideas there! Sounds like I'll need to close up the window and deepen the litter on the floor. The heating pad is covered with heavy vinyl and wrapped in plastic with a thick pad of newspapers for insulation underneath. I have it on a timer. It's off all night then comes on for an hour on high at 5 am to thaw it out. If it's not a really cold day, I turn it down to Med first thing in the morning, then it's on for 1/2 hour once every 1.5 hours through the day. It has worked like this so far, but it hasn't been below zero F yet. I can leave it on HIGH and on more often if needed.

It's not really made for that purpose. So far it seems to be fine. I don't know if it will last with that much wear. Time will tell. I can always buy one of those electric water heater things that it sits on if necessary.

I have a friend who bought some short roof heating cables and wraps one around the tall metal top of the waterer and that works for him.

I'm more concerned about the chickens themselves. I will put about a foot of litter on the floor for them, but most snuggle together up on the roost. There are four new ones who sleep on the floor, two together in a nest and two together in a corner. The coop is insulated but has a high ceiling.

This is their first winter and they don't like the snow on their feet, so don't venture out if it has snowed. I've been shovelling an area out for them. I even shovelled a path through the deep snow so they could go under the deck, but it snowed another 8" or so yesterday so they're stuck inside until I have time to do more shovelling. They have learned that they can fly over drifts and snow to get to a spot where they want to be.

Here's a couple of pictures of the shovelled path for them from the chicken house with a couple of chickens on their way:
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Here they are under the deck where the snow doesn't fall, surrounded by 2' of snow. They love it under there!:
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I wish I had the time to keep it shovelled for them.