African Architecture and Design writes on the “13 Principles of Sustainable Architecture” which fall under three categories “Small is beautiful”. “Heat with the sun. “Keep your cool”.. he writes “My wife and I (and our two dogs) have happily lived in a forty foot bus for the last four years. The key to this is efficient use of space, good organization, and keeping possessions to a manageable level. We do look forward to spreading out some in the passive solar, earthbag home we are building.