Up to -50 windchills-odd question about heating

[CJnCincy]

We are having crazy cold here in Northern Wisconsin. I have 5 hens. They have a nice coop, insulated, ventilated. Today was -27 and it stayed 13 in there. They have a heated water dish and have still been laying. But we are supposed to have even colder temps, record-breaking, in the next week or two and I'm worried. I have a 72 watt light bulb in there that I have had running 24-7 because it throws off a little heat, but that's all I have for heat. I was just brainstorming and was wondering about putting in a Himalayan salt lamp overnight? That way it throws off a little heat but not a bright light so they can sleep. Sounds odd, I know! Open to any ideas. Thank you!

Ohio here....not as cold as Wisconsin, but for the times when it is really cold (single digit or less), I use a ceramic infrared heat emitter lamp bulb (can find it on Amazon or other places) that I previously used in the brooder when they were just chicks. Our coop is about 48sq ft and holds 11 hens. While it never gets warm in there, it does break the bitter cold.

 

[Miss Lydia]

I keep the tops of my windows open on the south and east sides for ventilation. Also use a Sweeter heater when temps get low teens single digits, I have some birds over 8 yrs old, up to a hair short of 12yrs.

 

[WindingRoad]

Added more straw bales stacked around sides. Used over flooring and in nest boxes for warmth. Rest is structure and tarping if too cold.