Smarter Cities

How Green Urban Design Lowers Risk Of Climate Change Disaster

Saving rainwater and increasing green spaces are two small steps shown to help fight the ravages of climate change in cities.

A park in green Bogota
A park in green Bogota
Maria Monica Monsalve

-Analysis-

BOGOTÁ â€" Cities of the future may turn out to be friendlier, cleaner places than the desolate dumps science fiction films have been depicting in anticipation. A range of initiatives being taken around the world â€" some apparently of little importance, others bigger in scope â€" are already steering the urban future away from worst-case scenarios. Your children and grandchildren may end up avoiding the world of Mad Max or Blade Runner.

Certainly, cities are grappling with air pollution, massive trash generation and heaving population numbers. But many are also working on becoming more sustainable.

Susana Vélez-Haller, a forestry expert with the World Wildlife Fund, says cities are a paradox right now, requiring so many resources yet producing so little. Cities, she says, generate little other than "a lot of waste. The idea is to change that."

As centers of economic activity, cities are a magnet for people. Since 2008, the majority of the world's population lives in cities, and as a recent UN Habitat report indicates, this majority will become a third of all people by 2050.

That makes cities key to mitigating climate change and contributing to public health, food security and global welfare. "When we speak of sustainability," Vélez says, "one thinks of territorial planning, development, economy, efficient energy use, waste," and anything else that can be managed well enough to avoid the Mad Max scenario.

Green facade in Bogota â€" Photo: Juan Sarasua

So what can we do today to make cities amenable? One solution is green architecture and buildings that take their environment into account. Respecting the environment is "understanding that you are building in an existing ecosystem, which has its own conditions," says David Perico, head of Arquitectura Más Verde, a construction and landscape architecture firm. "That means exploiting the natural elements nearby, like favoring penetration of natural light depending on where the windows are, looking at wind to produce energy, and considering which building fronts can be used to gain or lose heat, depending on the climate."

A big winner in recent years has been the vertical garden. They provide thermal isolation on building sides and reduce the intensity of city "heat islands." A temperature difference between city centers and their peripheries is normal, says Perico. "While the city center is lukewarm at night and the periphery cold, this changes in the day," he says. "So these green walls can't just be thought of as another domestic technology but as a holistic, collaborative and social tool for the city."

Green walls return to nature a bit of the space taken from it by the city, provide a stop-off point or temporary shelter for migrating birds, capture pollutants and contribute to the welfare of residents on many levels.

No more floods?

Flooding and reuse of water are other issues modern and future cities must manage correctly. Runoff rainwater flowing into the drains from roofs or tarmac usually isn't treated, though it contains particles and synthetic material. "This is not just a flooding risk," says Juan Pablo Rodríguez, a civil engineering lecturer at Andes University in Bogotá. "It also has a major and negative environmental impact on rivers."

A response to this is for cities to have more filtering spaces such as soil and greenery, where water can gradually seep into the dirt. Soil and vegetation reduce flooding risks and act as filters for the water. Rodríguez says a study by his university has shown that runoff water from rooftop greenery is pH neutral, while green roofs also retain most rainwater through dry periods, and about 10% to 30% in winter.

Use of runoff water is elementary in Colombia, he says, but in places like the United Kingdom and Australia, systems have been devised to guide runoff toward areas of trees, where it is effectively stored. He observes that low-lying areas in urban parks can function as stores for use when water is more scarce, and suggests homes start using tanks to store the rainwater that pours onto their roofs.

Biodiversity returns to Colombian cities

The country's enormous range of fauna and flora is beginning to be explored for urban sustainability. "Colombia has been considering biodiversity strategies for 20 years now, though above all in rural areas and national parks," says María Angélica Mejía, a researcher at Humboldt Institute. Biodiversity provides such "services" as assuring the presence of pollinating agents in the garden or even aiding food security through city farming. This cannot be an obstacle in Colombia, she says, where so many country people have had to move into cities and have "harvesting in their genes."

Green spaces of any kind â€" be they forest segments or artificially created â€" are a crucial component of sustainable cities, she points out. "We have to have a green area within a five-minute walk," says Mejía, and any type of parkland can "supplement eco-systemic needs and contribute to our welfare."

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Green

In Argentina, A Visit To World's Highest Solar Energy Park

With loans and solar panels from China, the massive solar park has been opened a year and is already powering the surrounding areas. Now the Chinese supplier is pushing for an expansion.

960,000 solar panels have been installed at the Cauchari park

Silvia Naishtat

CAUCHARI — Driving across the border with Chile into the northwest Argentine department of Susques, you may spot what looks like a black mass in the distance. Arriving at a 4,000-meter altitude in the municipality of Cauchari, what comes into view instead is an assembly of 960,000 solar panels. It is the world's highest photovoltaic (PV) park, which is also the second biggest solar energy facility in Latin America, after Mexico's Aguascalientes plant.

Spread over 800 hectares in an arid landscape, the Cauchari park has been operating for a year, and has so far turned sunshine into 315 megawatts of electricity, enough to power the local provincial capital of Jujuy through the national grid.


It has also generated some $50 million for the province, which Governor Gerardo Morales has allocated to building 239 schools.

Abundant sunshine, low temperatures

The physicist Martín Albornoz says Cauchari, which means "link to the sun," is exposed to the best solar radiation anywhere. The area has 260 days of sunshine, with no smog and relatively low temperatures, which helps keep the panels in optimal conditions.

Its construction began with a loan of more than $331 million from China's Eximbank, which allowed the purchase of panels made in Shanghai. They arrived in Buenos Aires in 2,500 containers and were later trucked a considerable distance to the site in Cauchari . This was a titanic project that required 1,200 builders and 10-ton cranes, but will save some 780,000 tons of CO2 emissions a year.

It is now run by 60 technicians. Its panels, with a 25-year guarantee, follow the sun's path and are cleaned twice a year. The plant is expected to have a service life of 40 years. Its choice of location was based on power lines traced in the 1990s to export power to Chile, now fed by the park.

Chinese engineers working in an office at the Cauchari park

Xinhua/ZUMA

Chinese want to expand

The plant belongs to the public-sector firm Jemse (Jujuy Energía y Minería), created in 2011 by the province's then governor Eduardo Fellner. Jemse's president, Felipe Albornoz, says that once Chinese credits are repaid in 20 years, Cauchari will earn the province $600 million.

The Argentine Energy ministry must now decide on the park's proposed expansion. The Chinese would pay in $200 million, which will help install 400,000 additional panels and generate enough power for the entire province of Jujuy.

The park's CEO, Guillermo Hoerth, observes that state policies are key to turning Jujuy into a green province. "We must change the production model. The world is rapidly cutting fossil fuel emissions. This is a great opportunity," Hoerth says.

The province's energy chief, Mario Pizarro, says in turn that Susques and three other provincial districts are already self-sufficient with clean energy, and three other districts would soon follow.

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