What is the value of energy savings at the building level if we’re not also looking seriously at energy savings from transportation to and from our buildings? (See EBN
introduction to the topic in “Driving to Green Buildings: The Transportation Energy Intensity of Buildings
,” Sept. 2007.) Thanks to a study commissioned by the U.S. Environmental Protection Agency (EPA), we have some new answers to that question, at least for Energy Star-rated residential buildings. The energy savings realized through location efficiency
(walkable access to public transit and work, school, and retail centers) are greater than those achieved through home efficiency.
As this graph shows, transportation energy intensity for a conventional suburban development is so high that moving to a transit-oriented location makes a dramatic difference in energy use, even if home and vehicle efficiency remain the same.
In other words, a conventional home in a transit-oriented neighborhood saves considerably more energy—and money—than an Energy Star home in a conventional suburban development.
The study uses national energy-consumption data compiled by the federal Energy Information Administration and takes as its baseline a conventional home with conventional vehicles in a conventional suburban development. Given these assumptions, the report examined the relative energy savings expected from three different scenarios:
1. In a suburban house 20% more efficient than a conventional house, with vehicle efficiency increased to 37 mpg, potential energy savings would be a considerable 34%–38%, depending on housing type. (The 20% savings are in line with Energy Star expectations; the study did not consider higher-performing homes.)
2. A house and vehicles with conventional efficiencies, but located in a transit-oriented neighborhood, gained more impressive savings of 38%–50%.
3. A third scenario combined aspects of the first two: an efficient house and vehicle located in a transit-oriented neighborhood. Together, these strategies showed 54%–64% energy savings.
Although the environmental implications are significant, Matthew Lister of the Jonathan Rose Companies, the green real estate firm that prepared the report for EPA, told EBN
, “the underlying story is about quality of life.” The choice to live in a densely settled, mixed-use neighborhood, Lister argues, is not just about saving money or even the planet; it’s about “less time in the car and access to more choices,” as well as more work opportunities. The report also touches on social equity, he said. “People have to drive further and further out so they can afford a house,” but then end up “shackled to two car payments,” which raises the effective cost of their housing.
This chart illustrates the relative importance of energy efficiency and location efficiency for each housing type considered in the EPA study. Combining the two has the largest impact for all home types, but the biggest savings from changing locations are realized in multi-family dwellings, which are inherently more energy-efficient than single-family detached homes.
The idea of folding in transportation costs when considering housing affordability is gaining ground, thanks to the efforts of groups like the Center for Neighborhood Technology, the organization behind the term “location efficiency.” Whether actual home buyers would agree with Lister’s assessment about quality of life is an open question. There is a strong preference among many Americans for the privacy, lower crime rates, and better schools of the suburbs, and a willingness to pay a high price to live there, in the form of extra car payments, longer commutes, and frequent visits to the filling station.
Demographic changes and rising fuel prices could tip the balance toward location efficiency, though, Lister claims. “A significant number of active, aging Baby Boomers will be looking to get out of the large-lot, single-family homes” as they retire, he said. Lister and the other report authors hope local governments will begin revising zoning and planning policies in anticipation of that. When his company gives talks to city planners, he said, “municipalities are generally really excited” about smart growth. “They know all the buzzwords more than we do,” he said. “The planning industry is shifting toward this type of development.”
The study methodology has limitations, and Lister and his colleagues hope to pursue some finer-grained analysis in the near future. “Instead of just looking at national averages, we want to go to the regional level or municipal level” and apply the same methodology, he said—or possibly even use more stringent home efficiency variables, assuming the greater energy savings associated with LEED ratings or National Association of Home Builders certification. Either direction, he said, could potentially lead to a more detailed understanding of the relationship between location efficiency and building efficiency, and help inform better zoning policies and urban planning in the near future.
For more information
U.S. Environmental Protection Agency
February 25, 2011
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