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.
“Ultimately, higher energy prices cannot overcome the realities created by the car-oriented declustered environment in which we now live and work,” Kotkin wrote in a 2006 op-ed for the San Francisco Chronicle. A proponent of what he calls “smart sprawl,” Kotkin predicts that while roads will continue to serve as the backbone of the suburban matrix for the foreseeable future, commuting distances will be incrementally reduced as bedroom communities morph into archipelagos of self-sustaining villages that include both housing and employment.
This is a view shared, at least in part, by many of the nation’s foremost urban planners. In their forthcoming book, Retrofitting the Suburbs, architects Ellen Dunham-Jones and June Williamson forecast the emergence of “urban nodes within a new polycentric metropolis that simultaneously complement the core city’s downtown and serve a predominantly suburban population. They reflect both centeredness and decentralization.”
In other words, the suburbs seem destined to become more like mini-cities.
While there are inevitable nuances of opinion when it comes to rites of execution (e.g., which comes first, the transit or the housing?), the notion that urban neighborhood models might be used as grafts to reshape the sprawl landscape is gaining traction. Suburban compact growth can have many faces, be it a new urbanist greenfield town, a dying mall transformed into a mixed-use lifestyle center, or a transit village sprouting up around a light-rail park-n-ride. Such projects still account for only a single-digit percentage of the built environment, but they are gaining momentum as a softer alternative to hard-core city life.
As the Crow Flies: Conventional, meandering suburban street patterns (left) tend to necessitate longer driving trips and increase vehicle miles traveled, thereby increasing carbon emissions. Compact street grids (right) offer more direct connections and encourage walking as an alternative to driving.
Credit: Source: Dr. Lawrence D. Frank, Bombardier Chair in Sustainable Transport, University of British Columbia
“Suburbia as we know it will remain,” says Elizabeth Plater-Zyberk, an original founder of the Congress for New Urbanism, partner in the urban planning firm DPZ, and dean of the School of Architecture at University of Miami. “A lot of people will continue to go to great lengths to live that way. We’re not talking about eliminating or changing everything, but rather about rethinking the strategy for new growth and providing some alternatives that really didn’t exist until recently.”
But whether or not the market will shift fast enough to save the ozone layer remains in question. “It’s a fairly slow process,” says architect Doug Farr, author of the book, Sustainable Urbanism: Urban Design with Nature. His firm has joined hundreds of planners, builders, municipal governments, and nonprofits in backing the “2030 Challenge,” a campaign with a goal of reducing VMT by 50 percent over the next two decades. “Right now, you’ve got emphasis on the light bulb and where your gas is coming from and, to a larger degree, whether or not your building is green, but nobody talks about land patterns and walkability as a precondition of sustain-ability. If you add a green building to sprawl, what have you accomplished? There are half measures everywhere. The whole movement right now is very fragmented, and all of the solutions are partially right."
92%
Rate of population growth in 34 largest U.S. metro areas from 1950–1990
245%
Growth of urbanized land in 34 largest U.S. metro areas from 1950–1990
12,400
Average vehicle miles traveled per household in 1969
21,200
Average vehicle miles traveled per household in 2001
295 million
U.S. population in 2005
378 million
Anticipated U.S. population in 2035
420 million
Anticipated U.S. population in 2050
2.8 million
Acres of blighted grayfields that are expected to become available for redevelopment over the next 15 years
85 million
Metric tons of carbon dioxide that could be eliminated annually between now and the year 2030 by shifting
60 percent of new land development to compact growth
40%
Portion of total office space nationwide that is now located in the suburbs
$250 billion
Cumulative fuel cost savings that would be achieved with a 60
percent shift toward compact-growth patterns by 2030
71%
Share of older households expressing a preference for housing within
walking distance of public transit
45%
U.S. share of global automobile emissions
sources: “Our Built and Natural Environments,” EPA; BuildingGreen.com; Arthur C. Nelson, Metropolitan Institute at Virginia Tech; Growing Cooler: Evidence on Urban Development & Climate Change; AARP
Going To Town
Urbanized areas (including citiesand their suburbs) now house about half of the world’s population—a share that is expected to climb to 70 percent by the year 2050, according to a recent U.N. report. By mid-century, researchers predict the emergence of 27 megacities worldwide with populations topping 10 million, compared to just 19 today. The majority of growth is expected to occur in smaller cities, many of which will ultimately spread their borders and bleed into other metro areas. How these pieces of geography and the spaces between them are developed will have a pivotal effect on the earth’s well-being.
Urban-style neighborhood design is not a panacea for every locale, but many experts believe it to be a step in the right direction. While cities crank out the lion’s share of the world’s greenhouse gas emissions (80 percent, largely due to commercial buildings), a per capita assessment of their carbon load is telling. New Yorkers, for example, generate an average of 7.1 metric tons of greenhouse gases per year—two-thirds less than the 24.5 metric tons produced by the average American household. Chalk it up to shared walls, shared infrastructure, shared transit, and lots of walking.
The Boomburbs Cometh
Urban anatomy as we know it—a dense core surrounded by low-density suburbs and exurbs—may soon be a thing of the past. With the rise of regional megapolitan areas, Robert Lang, co-director of the Metropolitan Institute at Virginia Tech, foresees the emergence of “edgeless cities” and “micropolitan areas” (see illustration below) that will serve as the connective tissue between older central cities. “Urbanizing suburbs represent a tremendous investment opportunity,” he advised in a recent presentation. “These places will grab a large share of growth in the next two decades and will rival more distant suburbs as a location for new construction.”
Happy Medium
Architects and planners often joke that there are two things Americans despise: density and sprawl. But finding a comfortable compromise between the two may be the key to building a more sustainable future. While high-rise developments in the ’burbs will invariably elicit NIMBY protests over property values and traffic congestion, modest mid-rise projects that are more spatially compact (particularly those including core service retailers such as drug stores and dry cleaners) can significantly lower a neighborhood’s carbon output by reducing car trips, minimizing energy consumption through integrated building systems, and reducing municipal infrastructure requirements. Attached housing can also help provide the population density that is necessary to support public transit.
While historic sales data suggest that Americans still overwhelmingly desire single-family detached homes in conventional subdivisions, demographic shifts on the horizon may portend a populace that is more amenable to higher-density living. Arthur “Chris” Nelson, a fellow at the Brookings Institution and co-director of the Metropolitan Institute at Virginia Tech, notes that today’s households are more likely to be made up of single adults, couples without kids, or single parents. “As we live longer with biomedical advances, the implication for the housing market is that we will be spending proportionately less of our lives raising children,” Nelson told the audience at the New Partners for Smart Growth conference in Washington earlier this year. “By 2040, only 13 percent of the net gain in total households will be households with children, whereas 87 percent will be households without kids.” Demand for smaller, more affordable, conveniently located homes with smaller carbon footprints may be on the rise.
Urban anatomy as we know it—a dense core surrounded by low-density suburbs and exurbs—may soon be a thing of the past. With the rise of regional megapolitan areas, Robert Lang, co-director of the Metropolitan Institute at Virginia Tech, foresees the emergence of “edgeless cities” and “micropolitan areas” (see illustration below) that will serve as the connective tissue between older central cities. “Urbanizing suburbs represent a tremendous investment opportunity,” he advised in a recent presentation. “These places will grab a large share of growth in the next two decades and will rival more distant suburbs as a location for new construction.”
Density by Design
What does a sustainable suburban region begin to look like when compact development replaces sprawl? Many planners and researchers predict a shift from the present city vs. suburb dichotomy to a more polycentric landscape in which self-sustaining suburban “nodes” orbit around larger urban cores.
All in One
Compact suburban villages have the potential to reduce vehicle miles traveled by putting residences closer to employment, shopping, and recreation. Organic growth is often concentrated around existing or future transit lines.
+ Cities and towns made of village-like neighborhoods balance resource needs.
– In suburban sprawl, the city and its suburbs compete for resources.
Pocket Sanctuaries
Poor land-use decisions can compromise water quality, reduce vegetation buffers, and degrade wildlife habitats. Zoning reform allowing compact-growth models that cluster buildings together and preserve open space may be one antidote to this trend.
+ With compact growth, homes placed on 1/6–acre lots at a density of one unit per acre achieve a landscape preservation ratio of 80 percent.
– Conventional subdivision zoning places homes on one-acre lots at a density of one unit per acre, thus allowing no preservation of open space.
Common Ground
The automobile-centric model of the post-industrial age put highways and clover-leafs at the center of it all, creating environments that were outright perilous for cyclists and pedestrians. As an alternative, many planners now advocate alternative site designs featuring wide, walkable boulevards, central public greens, and street-activating mixed-use buildings.
+ Boulevards lined by mixed-use retail allow the town and highway to work in harmony.
– In auto-centric sprawl development, the highway guts the town.
Efficiencies Through Desegregation
Site planning that places a variety of housing types in proximity to each other can prevent the need for repetitive infrastructure development, which causes further environmental degradation and is a source of burdensome impact fees for builders.
+ The urban-style neighborhood allows five market segments to exist in close proximity at one-third to one-half the infrastructure cost.
– Suburban pod development requires major infrastructure build-out to provide for five segregated market segments.