Shelter has been a concern of humans and animals alike for the millennia. Animals, through their natural instincts, build nests and shelters to meet their needs for protection against predators and seasonal changes in the weather. Early humans sought shelter in caves and cliff dwellings and later began to design and build shelters based on the availability of natural materials. With the discovery and development of concentrated forms of energy such as fossil energy resources, humans began to design structures to suit their needs and comfort. The influence of increasing energy prices and the prospect of climatic changes has caused people to design buildings and structures that are more energy efficient and less intrusive on the environment. Today there are incentives to building construction projects that emphasize "green" materials and efficiencies. Interestingly enough, "going green" does not mean enduring hardships or lessening of the convenience and comfort that people have come to expect in modern homes and buildings. Building codes and practices are being developed that foster intelligent use of materials and resources to design and build desirable and energy efficient buildings and structures. (Contains 5 figures.)