Experts anticipate that roughly 89 million new or replacement homes will be built in the U.S. over the next 30 years to keep pace with population growth. If sustainability is to become part of the housing pro forma, land use decisions—i.e., where these houses are built in ­relation to other things—will be just as important as what the homes are made of and how efficiently they operate. The car trips Americans presently rack up traveling between home, work, shopping, and recreation are a hefty source of greenhouse gas emissions—by some estimates a greater offender than homes themselves.

Here’s an acronym destined to become a household term in the near future: VMT, or vehicle miles traveled. Since 1980, as cities and their adjoining suburbs have expanded into what Robert Lang, co-director of the Metropolitan Institute at Virginia Tech, refers to as “megapolitan” swaths of contiguous urbanized land, America’s collective odometer reading has grown three times faster than its population and nearly twice as fast as vehicle registrations. In their book Growing Cooler: The Evidence on Urban Development and Climate Change, authors Steve Winkelman, Reid Ewing, and David Goldberg note that if the na-tion stays its current course and continues to build auto-dependent subdivisions, an anticipated 48 percent increase in VMT between now and 2030 will easily cancel out any carbon ­reductions achieved by tougher fuel efficiency standards.

Building more efficient houses and cars is imperative, no doubt, but development patterns also matter in the green big picture, says Winkelman, manager of the Transportation Program at the Washington-based Center for Clean Air Policy. By his ­calculations, compact-growth patterns can reduce per capita VMT by as much as 30 percent by shortening driving distances and encouraging greater ­pedes-trianism and transit use. “People need to start believing that sidewalks are just as sexy ashybrid cars,” he says.

Many planners, local governments, and green-minded builders have already begun to embrace this line of thinking. Designed as alternatives to cul-de-sacs and strip malls, a growing number of new communities that have been sanctioned with progressive zoning codes are mixing a variety of dwelling types and retail/commercial spaces in close quarters with interconnected blocks, shared green spaces, and, in ideal scenarios, public transit.

As these alternative prototypes have begun to take root, much of the apocalyptic rhetoric of a decade ago—most notably, James Howard Kunstler’s prediction of the death of suburbia in his 1993 book, Geography of Nowhere—has given way to a more pragmatic consideration of how the built environment might be fixed. Walkability and transit access are core components advocated by new urbanists and smart growth-ers, although some experts contend that the first step toward measurable change is to acknowledge that not everyone in America is ready to give up their cars and move downtown.

Joel Kotkin, a Presidential Fellow in Urban Futures at Chapman University in Orange, Calif., notes that 92 percent of growth since 2000 has occurred in the suburbs, and an increasing number of jobs are migrating outside city limits to locations that are not necessarily served by public transit.

Learn more about markets featured in this article: Los Angeles, CA.