John,
OK, a "sunroom" is mentioned in 210.52, and I have seen sunrooms with all the outlets including heat and AC in them. So they can be used all year round. However what about those "porches" that can not be used in the winter? As Reno stated, these kinds of rooms, seem to creep from not being used all the time, to rooms that can be used. As Reno also stated, maybe the key word here is "Habitable". If the room is habitable at the time of inspection, then it should meet the requirements of 210.52. If the room is not habitable at time of inspection, then 210.52 doesn't count.
