Well, I live in Northern Wyoming and my chickens thrive in their unheated, uninsulated coop. I have operable windows that are always opened on the downwind side (and here winds in excess of 60+ mph are not unusual) plus lots of other openings that we leave year round. A couple of things to think about:
That kind of wall setup provides a lovely place for mice to move in and live happily right between them.
Insulation is great if the space is heated and you are trying to keep the heat in. But since you aren't trying to keep a "room" at 70 degrees, it really does little except hold in moisture, and moisture is the worst enemy in chicken keeping.
You chickens will come with a down and feather coat that most of us pay a fortune for. Comfy when the temps are really low, but miserable when it's warmer. I've picked up chickens in sub-zero temps and buried my hands under their feathers.....it's down right cozy next to their skin! Their "coats" do a remarkable job of trapping heat right where they need it. They already have the very best in insulation right where they need it.
The key to keeping chickens in cold climates is ventilation, and lots of it. You need place for moist air to leave the coop. Moisture settles on combs and wattles and causes frostbite. So you want your coop to have as many openings as possible without them getting a direct draft on them when they are roosting. A direct draft is one that actually ruffles those feathers and lets that trapped warm air escape. A coop that is tightly closed up is a recipe for disaster - moisture and ammonia will build to unhealthy levels in no time at all.
Go back to that down coat you spent a month's wages on....keeps you so cozy in winter, but if the zipper breaks and the trapped air gets out, you're an instant icicle! And that coat is worthless wet. So keeping your chickens dry and out of direct wind is key.
In the beginning I was going to insulate my coop too. @JackE and I actually got into quite a heated discussion about it. But he was absolutely right! His coop is totally open on one side...it's gorgeous and his birds thrive. I'll post a link so you can take a look.
In the end you have to do what you think is right. But I took the advice of a seasoned chicken keeper and haven't regretted it yet.
Edited by Blooie - 3/3/16 at 5:34am