The number of walkable areas in metro centers across the country is on the rise, signaling a dramatic shift in United States development trends, according to new report.

The report, produced by the Center for Real Estate and Urban Analysis at George Washington University in conjunction with LOCUS, a national network of real estate developers and investors, ranked the country's largest 30 cities based on the amount of commercial development in walkable urban places, or "WalkUPs."

Washington D.C., New York, Boston, San Francisco and Chicago took the top five spots. But the report also found that traditionally sprawling cities, including Miami, Atlanta and Detroit, are well-positioned for increased walkability based on current development efforts.

"This is a major change in how we build the country," said Chris Leinberger, president of LOCUS and author of the report, on a call with reporters.

Top-ranked urban places are now seeing "the end of sprawl" where at least 50 percent of urban office, retail and apartment space now takes up less than 1 percent of city acreage, he said. This is a marked change from the last structural trend following World War II when people migrated from city centers to live in drivable suburban areas.

The report found that walkable urban office space also gets a significant price premium of 74 percent over suburban locations, signaling a tremendous amount of pent up demand. With businesses wanting to attract young talent and the millennial generation wanting to live in urban centers, the authors hypothesize that more than 80 percent of future development will take up less than 10 percent of existing land mass in metro regions.

Major environmental shift

Walkable cities are correlated with a strong economy. These areas have substantially higher gross domestic product (GDP) per capita than their counterparts and high percentages of college graduates. Although the report notes that the causal relationship requires further research.

Walkable cities are also part of the solution to climate change. Buildings and transport collectively produce 38 percent of all U.S. greenhouse gas emissions, according to U.S. EPA. Electricity, by comparison, produces 32 percent.

So while much of the conversation on climate change has been focused on the supply side—making energy sources more renewable and more efficient—encouraging walkable cities will reduce greenhouse gas emissions by mitigating overall energy demand, Leinberger said.

"What we're seeing with walkable urban development is possibly the most important environmental change we in this country are making," he said.

But there are hurdles to increasing walkability. According to real estate developers, zoning requirements have stretched budgets and project timelines to between eight and 10 years. They say it's also been a challenge to get effective government support where transportation departments have been focused on building highways instead of cities.

Community groups tend to identify other issues. For instance, they argue WalkUPs escalate the affordable housing challenge, take away from the character of a city and can increase road traffic in certain areas.

Home sizes grow, along with carbon footprint

While some places grapple with how to build denser, others are still growing bigger. According to a separate, preliminary study released yesterday by Georgia State University, home sizes in the United States have been increasing throughout the post-war period.

Larger homes are associated with higher carbon emissions because they consume more electricity, and less dense construction generally encourages driving. The study found that public policy plays a distinct role in determining the size and density, and, ultimately, the carbon footprint, of U.S. housing stock.

"A policy that makes for larger, less dense housing is going to filter into more carbon output for a resident of that city," said Kyle Mangum, assistant professor of economics at the Andrew Young School of Policy Studies at Georgia State University.

Federal income tax deductions for mortgage interest and property taxes are one of the drivers toward larger homes. These incentives have increased annual carbon emissions by about 2.7 percent and almost 6 percent annually in new construction, primarily due to greater square footage per person. Putting in place stricter land-use regulations in high-carbon-output cities would decrease overall carbon emissions by about 2.2 percent and 4.5 percent in new construction.

But in some places, the shift to denser living might not yet we welcome, said Mangum.

"There's not an easy fix," he said. "It would involve giving up some of the things people like."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500