You might join & post on this board....

http://backyardchickens.yuku.com/

Lots of folks there with all kinds of knowledge about chickens!

I kept mine in chickenhouse but nice days left them out you know warmer but you need to remember theyll be seen easier against white background ,snow

You don't mention the breed of chickens. If they have short combs, just wrap the walls in plastic to cut the wind and your birds should be fine. The key issue is that they have to stay dry and out of the wind, then their feathers insulate them.You'll lose a few, but that's chickens. You'll have to feed them, and make certain that their water is available and not frozen over, or water them twice a day. I assume you have some predator protection? If not, you'll lose them to hungry wildlife.
My suggestion would be to butcher all but 6 (for eggs) and give those 6 an old shed or cleaned out dog house, with roosts for the night. It's not economically feasible to over-winter 40 chickens. That will give you time to build a sturdy snow-proof winter coop for the next winter.
Also, if you want to raise birds for eggs you'd be better off with ducks. Khahki Campbells or Welsh Harlequins have a better feed/egg ratio, lay more eggs and unlike chickens will lay well (usually an egg each a day) for their lifetimes, not for just 2-3 years. They thrive in winter conditions with minimal shelter (you can make mini tunnels the same as for crops if predation is not an issue)as long as they have constant access to fresh water. They don't need extra light to lay well in winter and the eggs bring in twice the money. And they are far hardier than chickens, they don't die off the same way- just don't give them medicated feed.