An EPA-supported study shows that if you’re concerned about energy use from urban development (in this case, residential buildings), you should look at location efficiency first, rather than building efficiency. The study describes location efficiency this way:
Housing that is located in a walkable neighborhood near public transit, employment centers, schools, and other amenities allows residents to drive less and thereby reduces transportation costs. Development in such locations is deemed to be “location efficient,” given a more compact design, higher-density construction, and/ or inclusion of a diverse mix of uses.
As the graph above shows, locating housing in location-efficient neighborhoods has a greater impact on the combined housing-transportation energy use than improving the performance of buildings and automobiles. EPA says that locating homes in these areas, where some automobile trips can be replaced with transit or other transportation modes, lead to reductions in household energy use of 39 to 50 percent. While I’m a little hesitant about the study’s assumptions of a 45 percent reduction in vehicle miles in TOD neighborhoods, the larger point is still valid: location has a large impact on energy use by urban development, larger than is often assumed, and deserving of more attention than it’s given.
The study uses energy consumption data for housing and transportation that was collected as national averages, not for any particular location. The “energy-efficient” homes data was based on Energy Star homes. So, of course, results from specific regions or cities may vary. Also, Energy Star is not the most energy efficient way to build a home, but it’s relatively affordable and has large market share compared with other home rating systems.
While location efficiency may be more important than building efficiency in terms of energy savings, it’s obviously a more complicated and politically charged topic than building energy efficiency. Improvements to buildings bring nearly immediate and focused benefits to owners, while decisions about density and location have benefits which are more widely distributed and whose paybacks accumulate over a longer period. Matthew Lister, who works for the firm that prepared the study, told Environmental Building News we shouldn’t just focus on the energy savings, though:
“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.