Thanks again for more interesting ideas. The sketch is helpful: those
are just about exactly the proportions of our fireplace/wall. No,
Kevin, the fireplace only takes up about a third of the total length of
the wall, so putting in windows and a door to the greenhouse would
work. Besides cost, I have to think about how this would look on this
old house -- it seems, at least from a heat/light/environmental
standpoint -- like a good idea.

Thanks again. If we decide to do this I'll report back.

Art