I can't offer much help, except to say when I went to pick up my small flock recently (first time sheep owner), the guy I bouight them from had a similar setup and I was very impressed.
I am kind of old-fashioned in that I prefer to see (and someday have) 200 year old New England barn-type buildings for my animals, but the benefits of the greenhouse structure were obvious from the minute I saw it.
For this particular setup that I saw, the owner had used/built a 4 foot knee wall all around, on which the greenhouse sat, giving extra height to the structure.
My own "barn" is a 30 year old steel "Butler" building, which is adequate at best, but dark and has low clearance(i.e. my trctor won't fit in)...as opposed to this bright well ventilated structure.
He was in Southern Maine and said the wind/snow were no problems at all...when you factor in the fact that a greenhouse type structure will probably cost 10-20% of a stick-built wood building, the pros becomes compelling.
In the summer, I guess you would need to make sure it doesn't get too hot, but seems like a great solution to me.