Although we are not in the zone where you are, we see very few nights that dip lower than the teens here; I will offer what I have learned in my time with chickens.... we have 70+ chickens, they are divided into two coops, one 4x8 enclosed for the Banties and another that is 4x16 for the standard breeds...all are allowed to free range our acreage when weather permits... that is to say, that if the temps dip below about 35*F, we do not allow them out until the temp reaches higher than that. They are all housed in a pole barn which legally can not be electrified, so we have done our own system to allowing lighting and a warmer light is used on days that they are enclosed , both for warmth and light to maintain egg production and keep their internal clocks correct... since I can not heat water, I just change it out a couple of times a day when it freezes... while it is true that you do not want them to become accustom to tropical temps and risk the sudden change in a power outage...it is not a risk to offer a small heat source such as lighting or maybe just extra insulation.... a great deal has to do with the breed and their hardiness to your conditions.... we have had some difficulty with certain small breeds in winter so we have decided to just not raise those breeds since we are not equipped to offer more in the way of temp protection... do not be afraid to give your chicks what they need, with only 5 hens, you should be able to make arrangements in the case of an outage to protect them...seems my guest room is always housing a sick, picked on, or special needs chicken, lol, so where there is a will, there is a way.... but do not worry about provided tropical conditions that would throw them into shock if it failed, just give them enough heat (light bulb) to assist them in warming ....they will take care of the rest if they are a breed for your area... good luck and I hope you enjoy your babies as much as I do

I agree with heartzlink, I think you will do just fine with your birds, provided they are a "cold hardy" breed. I haven't seen -20 here but it does get down to the negatives and then add the wind chill. I do keep a red heat lamp on out in the coop but I don't suppose they actually require it. I lug water twice a day in these temperatures as I don't have a heated pad or waterer. I keep the straw fresh and I think with that and the process the manure goes through, keeps them fairly comfortable. I just add to the bedding during cold weather, I don't ever clean it out during the winter. Well, I do clean out the nesting boxes. My chickens have also been "cooped" up for the past week due to bad weather. We had blizzard conditions Tues and a cold spell a day or so before. My chickens are freaked out by the snow, LOL! So I couldn't see opening the door for more cold to come in when they wouldn't venture out in the snow anyway. I think it helps to give them special treats when they are cooped up like that, I have saved all my appropriate kitchen scraps along with cooking them noodles (thanks for the idea, Velvet) and tossing in apples and other things to entertain them in their confinement. Lori

We have -35 celsius and sometimes colder here in Alberta Canada . I use a normal heating light ( the ones you use for baby chicks ) hang it up at a proper height, and we have no problems ( although with these temperatures egg production is near stand still )

I am near you in Barrie Ontario. We have winters that dip to -25c. I have a normal red heat bulb in a ceramic light socket in the roof of the chicken house, about 4' from the roost. I turn it on for them when the temps get around -13c with no problems. As soon as it gets warmer, I turn it off. At -10 they don't need it. It helps to prevent frostbite on comb and wattles. Rubbing petroleum jelly on the comb and wattles will help prevent it also.

Here is a link that might be useful: My Country DIY Blog

For water, use a Coleman (or other brand) small size picnic cooler. About 12 X 9 X 12", give or take a few inches. Fill with lukewarm water at daybreak. Except in really cold weather, it will stay unfrozen until dusk, and they go to bed anyway at that time. If it is protected, it will even go overnight without freezing.
Or, bring it inside at night, so that the insulation warms up.
Cheapest way to keep them watered that I've found.
My chikens are Chanteclers, so they don't get any insulation, or heat. And have no problems.

I spent too much time trying to keep my livestock in fresh water. I finally got a fountain and a heater for the chickens. I put a red heat lamp suspended about 4ft above the floor. Make sure it's secured well and has a dome cover. I really hate it when their combs get frost bitten. Make sure that there are no heavy drafts, but they also need good ventilation.

I use a red heat lamp. It's very important to make certain it's secure -- mine is wired to the chain it hangs on. And mine is significantly closer to a roost area than the others mentioned here -- it's just taller than the rooster's comb. They can move under it to warm up, then move away to do other things. This has worked for me for years.

Also, since my hens' "coop" is a box stall in the barn (with chicken wire around it to keep them from pooping all over the barn!), I cover the chicken wire with heavy plastic in the winter to keep drafts down. The wind is more of a threat than the temperature.

Good luck!

--Johanna

Here is a link that might be useful: Busy Solitude Farm

Looks like you have all the good answers already. We get below -40 (same in C and F) and a heat lamp is all we use. A heated bowl is required here to keep water liquid (or a fountain with a heater)however