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National
NRC Report: Compact Development Would Curb Driving, Reduce CO2 Emissions
As the U.S. population swells from 281 million in 2000 to 363 million in 2030 and almost 420 million in 2050, its housing stock of 105.5 million units will need partial replacement and expansion, first by a total of 57 million and then by 62 million to 105 million new units, a prospect in which the National Research Council's (NRC's) 12-member Committee for the Study on the Relationship Among Development Patterns, Vehicle Miles Traveled, and Energy Consumption sees an opportunity for a gradual shift toward higher urban densities and mixed uses, both necessary to cap and eventually reduce carbon (CO2) emissions.
If the current residential density was doubled, both through projects on the urban fringe and through strategic infill, with 75 percent of additional and replacement units in compact mixed-use communities and with their residents driving 25 percent less, the related Vehicle Miles Traveled (VMT), fuel use and carbon emissions would decline by 7 to 8 percent by 2030 and somewhere between 8 and 11 percent by 2050.
And even if only 25 percent of new housing units were located in such communities and if residents drove 12 or just 5 percent less, they would ensure reductions in the range of 1 percent by 2030 and 1.3-1.7 percent by 2050 or below 1 percent by that later date, respectively.
Some study committee members consider doubling the density of 75 percent of new construction feasible by 2050, because of macroeconomic trends such as higher energy prices and prospective carbon taxes, combined with increased public support for infill, transit investment, and transit-oriented development.
Others don't think it possible given prevalent housing trends, suburban land use policies and market preferences, unless states or regional agencies become decisively involved in growth management.
The committee identifies local zoning regulations that restrict density and mixed uses as one of the strongest barriers to compact development, noting its growing attractiveness to consumers, but also local concerns over traffic, taxes or property values -- legitimate, but sometimes at odds with wider demands for affordable housing and action against climate change.
In conclusion, the committee makes two recommendations: To encourage policies that support compact mixed-use development and reinforce its capacity for reduction of VMT, energy use and carbon emissions, and to make that relationship a subject of carefully designed studies, as necessary for more effective implementation of compact development.
Chaired by Harvard University Professor Jose A. Gomez-Ibanez, the committee included University of California-Irvine Professor Marlon G. Boarnet; PlanSmart NJ President Dianne R. Brake; University of California-Berkeley Professor Robert B. Cervero; METRO Portland, Oregon Senior Policy Adviser Andrew Cotugno; Brookings Institution Senior Fellow Anthony Downs; Clark University-Worcester Research Professor Susan Hanson; University of Texas Associate Professor Kara M. Kockelman; University of California-Davis Professor Patricia L. Mokhtrian; Cornell University Associate Professor Rolf J. Pendall; Argonne National Laboratory, Illinois Senior Economist Danilo J. Santini; and Oak Ridge National Laboratory, Tennessee Senior R&D Staff Member and Georgia Institute of Technology Principal Research Scientist Frank Southworth.
''It will take awhile for that new development to have a very perceptible effect,'' said Professor Gomez-Ibanez interviewed by USA Today writer Haya El Nasser. ''Even if we started (developing) more compact and densely today, given (that) new housing stock is only 1 or 2 percent of housing stock every year, it will be several decades before there is an impact.''
Public policy and smart growth experts regard major land use and transportation changes and linkage as imperative.
''The most important thing is to reduce the amount we drive. By just building two houses per acre from one house per acre would reduce (driving),'' pointed out Urban Land Institute Senior Resident Fellow Ed McMahon.
''What comes out loud and clear is that if the miles we drive continue to grow at the projected rate, you blow your climate goals out of the water,'' said Smart Growth America Communications Director David Goldberg about the NRC study. ''The basic message I got from this is that you can't go wrong by pursuing this strategy.''
Links to the free online report, its 4-page brief and 23-page Executive Summary at www.nap.edu/catalog.php?record_id=12747. -- National Academy of Sciences, USA Today 9/8/2009
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