The only issue with winter and "big" is that too big does = heat loss. Not saying don't go bigger than you think you'll need, absolutely do go big, but do also keep in mind the right ways to make your design efficient for the future. All this advice from a lady without chickens! LOL With ducks, I go 24 sq ft per duck outdoor pen area plus inside barn area that is ~6-8 sq ft per duck. Of course, all that's different with ducks. HTH anyway.