I've recently purchased a home with a glassed-in area at the entry. It is not heated.  It has skylights, a glass wall that faces east and has brick surrounding the other three sides.  I imagine it will get very cold in there (much like a garage, I would think).  I'd love to put  a substantial tree in there, one that's broad rather that high, and with leaves instead of needles.  That being said, I would still like an evergreen.  I was thinking of something like an olive tree, but I think the winters would still be too hard on it.  I'm looking for any suggestions... Thanks.