A new study that reinforces the belief that suburban sprawl is not a sustainable form of development has found that density does not necessarily bring more green benefits.
The anaylsis by the Council on Tall Buildings and Urban Habitat (CTBUH) compares the sustainability of people’s lifestyles across urban and suburban settings in the Chicago area from an environmental and social perspective. Dense Downtown vs. Suburban Dispersed: A Pilot Study on Urban Sustainability reexamines the conventional wisdom that has informed planning guidelines in cities across the world. While some of the findings were in line with expectations, others were somewhat surprising.
The report found that suburban development required 833 percent more infrastructure network length than downtown high-rises. The concentration of dense urban infrastructure exemplifies the most impactful benefit of tall buildings—in the reduction of materials and energy required to operate this infrastructure, says Antony Wood, CTBUH executive director and co-author of the study.
“The industry generally believes that urban density and verticality is a good thing, but there has never been a study that has looked at this in such granular detail. Most studies to date have been largely generic, based on large sets of generalized data,” he says.
While many of the findings support the assumption that dense cities are more environmentally friendly than dispersed suburbs, the data actually shows that more needs to be done to make downtown living a sustainable housing solution. For instance, on a per-person basis, high-rise residents consumed 27 percent more energy than low-rise residents—largely due to the high-rise residents being older “empty nesters” with less people per household. The energy required to condition shared facilities such as swimming pools, fitness rooms, and recreation areas in the high-rise setting also seem to be a factor.
“With more than a million people moving into cities around the world each year, it’s always been assumed that it’s much more sustainable for them to move into high-rise towers than into suburbia,” researcher and co-author Peng Du says. “But this study has shown that it’s not enough to make a blanket assumption that increased density is automatically more sustainable. We need to put more work into understanding how high-rise residents are living, and how their buildings work.”
The data was gathered from 249 household participants spanning four residential towers in downtown Chicago, and from 273 low-rise homes in nearby suburban Oak Park. The focus was on obtaining actual home energy and water bills, tracking transport movements by all travel modes, calculating infrastructure length, public open space and investigating residents’ satisfaction with life and a sense of community.
