Jim, here's another old thread that may have some useful information for you:
The thread "sunroom (Florida room)" in
Orchids forum
Not a coincidence that it is another thread from DrDawg, he has been very involved with GH growing for many years. At the time that he built this sunroom he was living in Mississippi, he has since moved to Florida. I think the room he built was larger than what you are thinking about, or maybe it will inspire you to go larger
At any rate, I'm really looking forward to seeing what you end up with!
