How Cities Can Fight Climate Change Most Effectively

What are the best ways for U.S. cities to combat climate change?  A new study co-authored by an MIT professor indicates it will be easier for cities to reduce emissions coming from residential energy use rather than from local transportation — and this reduction will happen mostly thanks to better building practices, not greater housing density.

The study analyzes how extensively local planning policies could either complement the Obama administration’s Clean Power Plan (CPP) of 2015 or compensate for its absence.  The CPP is intended to reduce greenhouse gas emissions from power plants.  In early 2016 a U.S. Supreme Court ruling halted the measure’s potential enactment; the legal case is unresolved and the Trump administration has announced it intends to unwind the CPP.

“Our take-home message is that cities can do a lot at the local level with housing stock,” says David Hsu, an assistant professor in MIT’s Department of Urban Studies and Planning, and one of three co-authors of a new paper detailing the study’s findings.  However, he adds, “In transportation, cities can’t make up for the loss of a national strategy.”

The researchers also found that policies with the biggest local impact vary from city to city, with faster-growing Sun Belt cities such as Houston and Phoenix having the potential to enact a bigger reduction in residential emissions than older cities such as Boston or Philadelphia, which see less change in their housing stock.

“For some cities, some policies will clearly be more effective than others,” Hsu observes.

The paper, “Intersecting Residential and Transportation CO2 Emissions,” appears online in the Journal of Planning Education and Research, with print publication forthcoming.  Hsu’s co-authors are John D. Landis, a professor of city and regional planning at the University of Pennsylvania, who is the corresponding author, and Erick Guerra, an assistant professor of city and regional planning at the University of Pennsylvania.
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In any case, as Hsu notes, the impact of policies related to construction standards and retrofitting alone is significant:  “You can do a lot of things at the local level to affect housing stock that are basically equivalent or even more aggressive than the Clean Power Plan.”

All told, housing accounts for about 20 percent of U.S. carbon dioxide emissions, according to the U.S. Energy Information Administration.  As the researchers state in the paper, the “full suite of residential energy conservation programs” could lower total U.S. carbon dioxide emissions by nearly 12 percent compared to the “business-as-usual” projections for 2030, when coupled with the CPP, and by 9 percent even without implementation of the CPP.
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The paper also makes clear that the average effects found across the 11 cities vary considerably.  Mandating that newly built homes be more energy efficient would reduce residential emissions by 10 to 13 percent in Houston and Phoenix, but only by 3 to 5 percent in slower-growing metro areas, including Boston, Chicago, Cleveland, and Philadelphia.

Read more at How Cities Can Fight Climate Change Most Effectively