When the new owner of a 1920's house called me in because his bedrooms upstairs needed a bathroom, I pulled off some drywall in the back of a closet and found the space he needed, in a closed-off dormer sitting unused over his dining room. (I live for such moments.)

The owner is gradually renovating the house himself, and is incorporating many green technologies, including hydronic heating, rainwater collection, and a grey water system.