by Rick Pruetz, Vice President, Ecocity Builders
Compact urban form, by itself, can cut resource and energy use in half concludes a report prepared by the International Resource Panel (IRP) for the United Nations Environment Program. Stopping or reversing sprawl is not easy. But some cities are doing it. And clearly cutting environmental impact in half makes it well worth the effort.
As some readers may recall from one of the four keynote presentations at Ecocity World Summit 2019 in Vancouver, compact urban growth is just the first of four levers of change recommended by the IRP in its report entitled The Weight of Cities: Resource Requirements for Future Urbanization. The others are: livable, functionally and socially mixed neighborhoods; resource-efficient buildings as well as urban waste, water and energy systems; and sustainable human behaviors. Significantly, the IRP found that all four of these levers can each reduce energy and resource consumption at least in half. Plus these levers are also multiplicative: when they are employed in an integrated, mutually reinforcing manner, they can decrease resource use by 80 to 90 percent when compared with the resource consumption levels associated with current business-as-usual (BAU) practices (IRP 2018). Since the IRP’s four levers correspond to several pillars and standards of the Ecocity Framework, cities can also cut urban energy and resource consumption by 80 to 90 percent by using the Ecocity Framework.
Over the last two centuries, most cities have generally become less dense, consequently decreasing the efficiency of embedded resources (those used in the construction of infrastructure and buildings) as well as the energy and other resources used in the operation of the built environment. Between 1800 and 2000, 28 of 30 world largest cities saw their densities drop by 1.5 percent per year. The price of urban inefficiency is clear in the United States, where the cost of sprawl has been pegged at $400 billion per year. This inefficiency can also be measured in energy waste and greenhouse gas (GHG) generation. The IRP report compares Atlanta with Barcelona, which have comparable populations and income levels. However, Atlanta is 27 times less dense than Barcelona and emits almost 11 times more GHG per person than Barcelona (IRP 2018).
Although resource-efficient urban form is achieved by both restricting sprawl and promoting compact redevelopment, this post exclusively addresses the power of keeping growth in its place by reserving and restoring greenspace around cities.
Reserving Greenspace – Consistent with the time-tested principles of good planning, the IRP emphasizes that natural features should guide urban form. Greenspace can cool neighborhoods, manage rainwater naturally, offer sources of local food, provide safe pathways for non-motorized mobility, preserve ecosystems, and create greater contact between people and natural environments. To quote from the IRP report:
An interconnected system of natural spaces, ranging from a regional greenbelt to a pocket play park should, from a landscape ecology perspective, provide the main structuring elements of urban settlements. This principle reflects the importance of identifying natural systems and strategic landscape patterns, which protect valuable ecosystem services and biological hotspots, and designing the city around them (i.e. linking these systems if fragmented (IRP 2018, p 119).
One of IRP’s case studies comes from Copenhagen, Denmark, which created compact urban form by concentrating growth around major public transportation routes. This strategy left greenspace, known as green wedges, between these radial transit corridors. Realizing that the green wedges were vulnerable to suburban sprawl, Copenhagen and its neighboring jurisdictions filled them with parks, athletic fields, golf courses, forests, community gardens and landscape protection areas. As a result, average citizens were more likely to value these open spaces and Denmark officially adopted the green wedges in the National Planning Act of 2007.
Copenhagen has now become a world leader in eco-mobility and climate action. Between 2005 and and 2014, Copenhagen’s population grew by 15 percent and its economy rose by 18 percent while its carbon emissions fell by 31 percent. Currently, 62 percent of Copenhagen’s work trips occurs on bikes and one third of suburban rail passengers use bicycles to solve the first/last mile problem. By 2025, Copenhagen wants ecomobility to account for 75 percent of all trips and to make this city the world’s first carbon-free capital (IRP 2018; Pruetz 2016).
Restoring Greenspace – Although it is not typically easy, many communities are also transforming previously-developed land back into greenspace. Some have daylighted streams, revitalized floodplains, or similarly restored other natural areas in ways that form and link nodes as recommended by the IRP report.
Vitoria-Gasteiz, Spain, created a greenbelt around its compact urban area by restoring abandoned gravel pits, garbage dumps, the Zadorra River and a previously-disturbed 247-acre into the internationally-significant Salburua Wetlands. The city refers to this greenbelt as an eco-recreational corridor since it now offers 91 km of walking/bicycling trails. Significantly, the greenbelt also establishes the boundaries of Vitoria’s urban area, where the city’s process of re-densification succeeded in capturing 97 percent of the municipality’s total growth between 2001 and 2010. As an indication that this strategy is working, even though the population of this city of 250,000 people has tripled since the 1960s, 81 percent of the population lives within 1,500 meters of the city center and over half of all trips here occur on foot (Pruetz 2016).
To accommodate population expansion without sprawl, cities have to grow up rather than out by redeveloping to higher densities within the current urban footprint, a topic addressed in the next post.
IRP (International Resource Panel). 2018. The Weight of Cities: Resource Requirements of Future Cities. Paris: United Nations Environment Programme.
Pruetz, R. 2016. Ecocity Snapshots: Learning from Europe’s Greenest Places.
Hermosa Beach: Arje Press.