Research Rest-Stop — The Sustainable City

Every Wednesday, the Mayor’s Office of Transportation and Utilities presents a new and interesting piece of research that highlights transportation, energy, or sustainability. 


Urban minded planners have long argued that the key to sustainability is compact living – a large number of people living in a small area will use fewer resources than a small group of people living spread out across a large area.  This argument makes intuitive sense, for example, an automobile and its required fuels are not needed if a person only needs to travel a few city blocks to reach a grocery store, while a person living in a sprawling exurb may need to drive ten miles to reach the nearest grocery store.  In this scenario, living in a denser city is more environmentally sustainable than living in a suburb or exurb.

A recent report, titled, “Growing Cities Sustainably: Does Urban Form Really Matter?” explores the common assumption that density equals sustainability. Furthermore, the report defines Sustainability as more than environmental – true sustainability also includes social equity and economic efficiency.  The study shows that Urban Form – dense city, clustered suburb, or sprawling exurb – has only a modest effect on energy consumption and land use, and has no significant influence on an area’s overall sustainability.  Density does not necessarily equal sustainability.   

Center City Philadelphia


The study examined the three types of urban form and used statistical models to forecast growth and change in land use over thirty years.  Then the models explored different sustainability indicators to measure economic efficiency, resource use, social impact, and environmental impact of the three urban forms.

Moreover, the report discusses that although there were differences between the sustainability for each form, no one form was clearly superior.  For instance, a dense city has lower transportation costs thus more environmentally sustainable, but dense cities have much higher land and property costs, thus economically non-sustainable.

This means that Center City Philadelphia should not automatically be considered sustainable because it is a dense urban area.  According to “Connections,’ DVRPC’s Regional Long Range Plan, Philadelphia’s land use will not change greatly between now and 2035, there will be slightly more job growth along with a slight increase in population, and Philadelphia will continue to lead the region with the least per capita emissions.   


Triple Bottom Line Benefits from Philadelphia’s Green City Clean Waters Program (Click image to enlarge)

Furthermore, the City of Philadelphia has actively committed to becoming a sustainable city in all regards, as evidenced in the Green City, Clean Waters initiative, where Philadelphia has set for itself a triple bottom-line to achieve Economic, Social, and Environmental Benefits, which include employing people in green jobs, increasing recreational opportunities, and restoring Philadelphia Ecosystems.  Becoming a truly sustainable city requires a comprehensive approach that addresses all measures of sustainability and the City of Philadelphia is working hard to make true sustainability a reality.

Want to know more?

Read the full report – Growing Cities Sustainably: Does Urban Form Really Matter?

Read Philadelphia’s Green City, Clean Waters Program

Read DVRPC’s Long Range Plan for the Region


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