I'm in the NE US, garden zone 5-6, and last winter, my first with chickens, was bitterly cold. My coop is draftless, well ventilated and dry inside, with deep (15-20 inches) of pine shavings, and i never saw condensation or moisture on the windows, but i think it was just too cold and damp outside in general last year.

Despite all the advice, and all my research, i ended up putting one small radiant flat panel heater on one side of my coop when i noticed the tips of one my RIR's comb starting to turn dark. It helped a lot, without making it actually warm in the coop. It was just enough to take the edge off. No frostbite afterwards, and no permanent damage.

We have crazy wind here too, windchills were often in the teens, so i put thick, clear/whitish pvc tarps up on top and around most of the run, so it would still be bright inside the run during the day, but most of the wind, freezing rain, and snow couldn't blow in.

I've heard mixed things about Vaseline on combs and wattles, (that it can make them freeze worse by trapping moisture underneath and bc vaseline itself can freeze), and personally haven't wanted to risk it.

The premier 1 nipple heated waterer is really great btw for keeping water liquid. It's great in the summer, too, bc its insulated so when i put ice in it, the water stays very cool. Hope this helps.