Science & Tech

International conference thinks about sustainable cities

6 min read

Changes in next 50 years may dwarf those of past 50

What will the cities of the future look like?

Harvard’s Graduate School of Design (GSD) offered some ideas last week at a three-day international conference, “Ecological Urbanism: Alternative and Sustainable Cities of the Future,” April 3-5.

The time is right, said organizers. Today, more than half of the world’s 6 billion people live in cities — and by 2050 two-thirds will dwell in energy-intensive urban areas. At the same time, cities face pressures related to health, climate change, air pollution, traffic, and reliable supplies of energy and water.

Designers can help reduce the environmental impact of cities, organizers said. After all, the energy to light, heat, and cool urban buildings accounts for nearly half the globe’s burden of greenhouse gases.

In the United States, a majority of the country — more than 280 million people — live in urban areas. Since 1950, most of the 10 most populated U.S. cities have shifted from the Rust Belt to the Sun Belt — creating centers that, by and large, are less racially and economically diverse than their older counterparts.

Big U.S. cities in general are less racially and economically diverse than they were 50 years ago, said conference presenter Lizabeth Cohen, Harvard’s Howard Mumford Jones Professor of American Studies and chair of the History Department. “Let’s not forget the social dimension of sustainability.”

Or the impact of cities on health. There were lunchtime conference discussions on obesity and mental health in the urban environment.

Or even what activist art can do in cities. John Bela, a director of the San Francisco design and art collective Rebar, described one project: an annual Park(ing) Day that turned a few square feet of a public parking space into a patch of green, rest, and shade that could be leased for 5 cents a minute.

If future cities are going to work, designers will have a hand in it, said Harvard President Drew Faust, who addressed the assembled experts Saturday (April 4).

“There is an invitation here to turn crisis into opportunity,” she said. “You here in this room have been given the mantle of the future.”

Visions of that future could be seen between sessions in a winding, colorful exhibit on display through May 17 in Gund Hall.

There were small-scale marvels, including energy harvesting textiles, electric cars that stack like shopping carts, and fritted glass that shimmers like beads to let in light and temper heat.

There were grand, wistful visions of the future, too. In a mural of “vegetal cities,” bicycles wheeled along grassy roadways under trellis-like wooden bridges and in the shade of buildings roofed with vegetation. Imagined “archiborescent cities” rose wave-like at seaside, nestled in desert canyons, and limned a forest with tree houses.

The conference sessions in Piper Auditorium, crowded with nearly 500 registrants from across the world, had a harder edge.

As modern cities grow up and out, what sustainable systems will deliver food, energy, and water? How will cities deal with noise, light, and odor? To reduce the urban carbon footprint, how should new buildings be built and old ones fixed?

First, grasp the big picture of Earth’s fragile and limited resources, said Mahadev Raman during a Sunday (April 5) session on engineering ecology. He’s an engineer with the global design firm Arup and teaches sustainable design at Princeton University.

An imaginary globe filled with the Earth’s water would barely cover Europe, he showed on a slide of the world map. A similar globe filled with the planet’s entire atmosphere is even smaller. “Our ability to pollute is quite significant,” said Raman.

A small dot on the same slide represented all of Earth’s fossil fuels. “That’s the tiny thing we’re all fighting for,” he said — and a third of it is already gone.

Meanwhile, buildings alone give off the lion’s share of global-warming pollutants, said Raman, using U.K. cities as an example of the developing world’s energy appetite. But he pointed to “the hope in this story”: In a world that now uses 15 terawatts of energy a year — that is, 15 trillion watts — renewable sources promise much more.

The potential energy from wind is 370 terawatts a year, said Raman, and from solar is an astonishing 89,000 terawatts annually. “There’s plenty of renewable energy around,” he said. “There is a ‘there’ there.”

But the potential of renewables can only be realized by finding what has been missing so far, said Raman: “the willingness to invest.”

Cities can save energy, too, with loop-like “industrial symbiosis” — regional systems of sharing excess materials and energy. University of Toronto landscape researcher Pierre Bélanger, who will join the GSD faculty in July, outlined the example of Kalundborg, Denmark. Garbage is burned for energy, he said, and waste streams from industry are “repatriated” for other uses.

Another example of the hope and potential in the built environment ran like a thread through the three-day conference: Masdar, a $22 billion planned city near Abu Dhabi in the United Arab Emirates (UAE). It has been designed from scratch to be a solar-powered, low-carbon city of 2.5 square miles of reclaimed desert.

A comprehensive look at Masdar came from someone who has worked on the project: GSD Adjunct Professor of Environmental Technology Matthias Schuler, a managing director of the climate engineering firm Transsolar.

Hot desert winds will be channeled along short, shaded streets and cooled through finger-like parks irrigated with waste water. There are limitations, said Schuler, including the realization that solar power will not be enough to fill the little city’s needs.

“Masdar is an experiment,” said Raman later. “It will teach us a lot” — even though the biggest challenge “is how to make existing cities work.”

Christoph Reinhart, who teaches architectural technology at GSD, said energy-efficient structures can go up “anywhere in the world” — at a price. A 50 percent reduction in energy use (compared to a conventional building) would require a premium of as much as 15 percent; an 80 percent reduction might cost a builder up to 30 percent more.

But any efficiency gains depend on occupant behavior, said Schuler. The way occupants act can more than double the energy a building saves, or double the energy it uses.

“We’ve gotten into some very bad habits in terms of consumption,” observed Raman. “Future generations are going to have to do more with less.”