There is no strict definition of sustainable underlying the selection of houses to illustrate and describe, just a strong sense that they display features that houses will incorporate more and more as fossil fuels become more expensive. The 48 houses are located in a number of climates and countries, and though some include active features such as solar energy, the environmental elements are mostly passive. Distributed in North America by ACC Distribution. Annotation ©2011 Book News, Inc., Portland, OR (booknews.com)