Just like a glass of ice cold tea will sweat to the outside of the glass, a chicken coop can sweat to the inside if there is too much humidity or tempature variation between inside and outside.
I'm sorry that I can't remember the name of the coop design, but there is a 3 sided coop (with no wall on south) that works great even up north.
As the wind whips around from the north, it should not blow in the southern windows and freeze the chickens. Someone on here should remember the name for this kind of coop. The designer is a genius when it comes to fluid dynamics!