Keeping Poultry in a Northerly location creates more challenges when it comes to the coop. To heat the barn it is best to rely on the body heat of your flock. This being said there must be enough room in the barn to allow your birds enough room to live confortably. So the result is a rather large flock in a fairly good sized barn. I house around 80 - 100 birds is this barn. My barn was built with typical 2X4 framing and isolated with R12 pink fibregrass insolation. A heavy plastic vapor barrior is put over the insolation. The inside of the barn I sheat with 1X4 spruce boards simply because in the damp amonia conditions during winter OSB strandboard tends to swell absorbing too much moisture.
Especially during winter months it is important that fresh air is allowed into the barn and stinky amonia air must vent out. I have vents in the ceiling of my barn that allow stinky air to escape into the attic and out the vents on the gables of the barn. Air enters the barn via a gap above the door. So a ballance is kept to allow temperatures not to dip below -5 Celcuis even when outside tempertures dip to -40 C.
Straw is the mainstay bedding of choice harvested as square bales. I use wood sawdust/ash for dust baths during winter months.