TORONTO — Many Canadians start summer days in bucolic settings, drinking their morning coffee amid thickets of trees, shrubs and other plants while watching birds nesting nearby. But these people are in the countryside or the suburbs, not steps away from noisy, congested streets and teeming office towers.
That may soon change in Canada’s largest city.
A Toronto-based firm, Brisbin Brook Beynon Architects, has unveiled a proposal to build a 27-story condo building spanning an entire city block in Toronto’s downtown core. The building would slope up toward its peak, creating giant terraces home to about 500 trees. The vegetation would serve a fundamental purpose rather than an ornamental one: to reduce the city’s overall carbon footprint.
[READ: Milan’s Ambitious Plans to Be Cleaner, Greener]
The building on Designers Walk, a commercial area in an upscale neighborhood, would be Canada’s first “vertical forest” — and one of at least a dozen architectural projects of its kind completed or now under construction around the world. Proponents say these buildings are good for the environment and have the potential to change the way millions of urbanites live. Detractors have raised doubts about their environmental contributions and sustainability.
During the past decade, population growth has risen dramatically in metropolitan areas. A little more than half of the world’s population now lives in urban centers, according to the U.N., and that number is expected to increase to 68 percent by 2050. As a result, construction has been booming and green space has been disappearing, negatively affecting the climate, air quality and living conditions in cities.
Recognizing the need for innovation, some architects have turned their attention to biodiverse urban landscapes. The most well-known is Italian architect Stefano Boeri, whose firm, Stefano Boeri Architetti, spearheaded the creation of the world’s first vertical forest: Il Bosco Verticale, a pair of residential towers that opened in Milan in 2014.
The towers, which are about 360 feet and 250 feet tall respectively, together host 800 trees — some as tall as 30 feet — 4,500 shrubs and 15,000 other plants. The buildings have geothermal heating systems and other energy-efficient features, and are also home to countless insects, including bees and hoverflies, and hundreds of birds.
The design and construction of Il Bosco Verticale was elaborate. Horticulturalists chose the plant species that would thrive in Milan’s climate and engineered the soil, while experts in wind forces took steps such as testing the planters in wind tunnels to ensure the trees would stay put. Today, four years after completion of the project, specialists in high-altitude pruning keep the plants trimmed while others oversee the automated irrigation system and ensure the entire building system is performing optimally.
Boeri and other proponents of vertical forests say their vegetal systems counteract the negative impact of urban microclimates; their foliage purifies the air by taking in carbon dioxide and small-particle pollution while releasing oxygen. Boeri says Il Bosco Verticale absorbs 30 tons of carbon dioxide and produces 19 tons of oxygen a year.
Vertical forests are also good for the mental health of occupants, proponents say, because the foliage muffles surrounding city noise and brings residents closer to the natural world.
“People who live in these buildings feel a connection to nature,” says Brian Brisbin, principal at Brisbin Brook Beynon Architects in Toronto. “Being surrounded by trees in an oxygen-producing environment has a dramatic effect on overall wellness and happiness.”
In Toronto, the proposed vertical forest could also further Mayor John Tory’s plan to significantly expand the city’s tree canopy so that it covers 40 percent of the city.
In the past few years, several other architectural firms have proposed or built structures featuring urban forestry — each one with design, foliage and animal life suited for a particular climate.
Boeri has developed designs for vertical forests in several European cities, including Paris; Treviso, Italy; Lausanne, Switzerland; and Utrecht, Netherlands, among others. He’s developing tree-clad buildings in several Asian countries, too. In China, there are plans for urban forest projects in cities such as Nanjing, Shanghai and others.
Two of Boeri’s vertical forest projects in particular have generated a lot of media interest.
The first, a 19-floor structure in Eindhoven, Netherlands, is slated to become the first vertical forest used for social housing. Residents from low-income groups will live in a 240-foot-tall skyscraper whose facade will provide a home to 125 trees, 5,200 shrubs and more than 70 other plants.
In Liuzhou, a city in southern China, Boeri has spearheaded the development of an entire “forest city” estimated to be completed within two years. The 432-acre area will be home to tree-covered office blocks, houses, schools and hospitals.
In Toronto, Brisbin’s team, which includes architects, foresters, landscapers and a developer, anticipates the city will give the project final approval next summer.
“We’ve developed the science and deployment system and we’re working on a maintenance manual now,” says Brisbin, who once rented an Airbnb in Il Bosco Verticale to learn more about the inner workings of the towers. “Everything is ready to go.”
Assuming the plan is approved, the University of Toronto and Vineland Research and Innovation Centre, an Ontario-based research organization dedicated to horticultural science and innovation, will select the trees to be included in the Designer Walk building and tend to them for two years before installation. They will later monitor the building’s water and the soil nutrient density to determine whether the building’s microclimate suits the vegetation.
Some individuals and organizations have expressed misgivings about vertical forests.
Lloyd Alter, an adjunct professor at Ryerson University School of Interior Design in Toronto, says that vertical forests use more concrete than conventional buildings, and that concrete creates 5 percent to 7 percent of the carbon dioxide produced in the world. “It would take a hundred years for the trees in one of these structures to compensate for the carbon footprint the building creates,” he says.
Alter, who is also the design editor of Tree Hugger, a blog that focuses on sustainability, is also concerned that the planters in vertical forests aren’t big enough to allow the trees to survive long term.
The Council on Tall Buildings and Urban Habitat, a U.S.-based nonprofit organization that focuses on the inception, design, construction and operation of tall buildings, has also voiced concerns about the viability of trees surviving in vertical forests.
“These trees are being taken out of their natural habitat,” Antony Wood, executive director of CTBUH, said in 2015. “Those higher up — that are subject to high wind speeds and different environmental pressures — are under greater stress than those lower down. What we don’t know is what are the longer-term ramifications on the trees themselves.”
Alter says maintenance is a concern, too. “In some instances, people are repelling down the sides of these buildings to maintain the trees,” he says. “How much does that cost? How much is involved with maintenance overall? Is it worth it?”
Landscape architect Robert Wright thinks it is. Wright, dean of the University of Toronto’s Faculty of Forestry, is part of the team behind the proposed Designers Walk building. He admits the that vertical forests aren’t going to end climate change, but remains steadfast in his support of them.
“The densification of our cities is important,” he says. “If we don’t make our cities more dense, we’ll end up taking up more space. We’ll build on wetlands, for example, and further harm our environment.”
He notes there will be a tall building on the Designers Walk site regardless of whether it has trees.
“If it’s not a vertical forest it will be a conventional building,” he says. “The question is, would that building be better with or without the ability to increase biomass, biodiversity and canopy cover?”
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A Vertical Forest Is Proposed in Toronto, Canada originally appeared on usnews.com
