In the United States, building "smart" — striving for compact, mixed-use, walkable neighborhoods — can be hard. There are many reasons: less-proven markets for pedestrian-oriented neighborhoods, higher costs of building, inflexible mortgage lending requirements, often-rigid building codes and zoning regulations, and the community opposition that may challenge any development. — Published 2003.0604
Vast quantities of resources are consumed in residential construction. Although an expanding array of new technologies are available and innovative practices are being developed to reduce the environmental costs of such construction, integrating environmental improvements into mainstream homebuilding remains a challenge. — Published 2002.0116
