An efficient house is one you get to and from by rail and foot. It's also a bit on the small side. Sprawl is the efficiency problem in housing, not so much the materials and construction.

I get the feeling Woz is missing the forest for the trees. Efficient housing is not a technological problem. Many very old houses are quite efficient. It is a political problem:

http://sociology.ucsc.edu/whorulesamerica/power/local.html http://www.sprawlkills.com/files/jeb_bush_leading_land_glutt...