sustainable has a more precise meaning that is often obscured, distorted, and diluted by the commercialization and marketing of the green “movement”. In the context of our built environment sustainable takes its meaning from “sustainable agriculture“, or “the ability…to produce food indefinitely, without causing irreversible damage to ecosystem health”. If we accept this as the basis for the definition sustainable building everything changes. For example, a 5,000 SF home with a HERS index of 70, bamboo floors, and Energy Star appliances may be “green”, but it is NOT sustainable. In the context of Global Warming and even the most optimistic projections of Peak Oil and Gas, only a home that meets zero energy standards can be considered sustainable.