By Tracy Hanes

Is There Room To Grow For Toronto’s Vertical Forests?

Within the next few years, a forest will rise from the concrete and asphalt along Davenport Road and Bedford Road in Toronto’s upscale design district. Instead of sprawling horizontally along the street, the trees will be integrated with the structure of Cityzen Development Group’s 22-storey Designers Walk condo to create the first vertical forest in Canada.

The mixed-use boutique building will resemble a sloping urban hillside, hosting 450-plus trees on its large, angled balconies. It’s designed by architect Brian Brisbin of Toronto firm Brisbin Brook Beynon, who was inspired by Milan’s Bosco Verticale (Vertical Forest), a prototype for a growing global trend. Brisbin had been intrigued by the Bosco Verticale and found a like-minded visionary in Cityzen and its president Sam Crignano. The developer is also behind Mississauga’s iconic “Marilyn Monroe” curving towers, so it doesn’t shy away from forward-thinking architecture.

Designers Walk is a leap ahead of what’s required under Toronto’s Green Roof Bylaw. In 2009, the city became the first in North America to adopt a bylaw requiring green roof requirements on new developments or additions with 2,000m² or more in gross floor area, representing a range of 20-60% of available roof space of a building. Since it was adopted, about 500 green roofs have been created in Toronto on new commercial, institutional and residential buildings.

Designers Walk

Eleven years prior to the bylaw, Mountain Equipment Co-op (MEC) pioneered one of Toronto’s first green roofs on its King Street West store; it covered 10,000 square feet with grasses and wildflowers. Lloyd Alter, retired architect, sustainability writer and adjunct professor at Ryerson University School of Interior Design, says green roof design has evolved since then. “MEC didn’t even put a stairway to its green roof. You had to get to it by an access ladder,” he notes. “Nobody thought of it as an amenity and there was no bug or bird habitat.”
Since then, developers have realized that people enjoy spending time on green roofs and they are now “a very much considered public amenity,” says Alter.

Designers Walk residents won’t have to venture to the roof to enjoy trees or greenery; they’ll just have to walk out to their balconies. Growing trees in the sky isn’t easily achieved, however.

“Structurally, the building has to be designed to accommodate the trees and there has to be consideration of their maintenance, pruning and replacement,” says Crignano. “When someone is sitting in their suite, you want to make sure light penetrates into the unit. There are so many aspects that we are still considering and we are far from complete in terms of design.”

Crignano says a lot of science and technology is involved in creating the Designers Walk vertical forest, including elaborate watering and feeding systems controlled by computer. “We’ve always done terraces with some minimal landscaping, and green roofs are something most of our buildings have, but that’s the extent of it. There is nothing remotely close to this.”

Each tree will have an individual identification that the computerized off-site system will monitor. Sensors will track irrigation and nutrient levels, as each tree’s needs will vary, depending on their floor and orientation. Cityzen is looking at planting a mix of deciduous and coniferous trees so the balconies and building stay green year-round.

Cityzen is finalizing the site plan approval with the city, with the goal to go to market in mid-2020. The building will be 22 storeys high but the unit count has not been finalized. “I think at the political level there was an embracing of the idea, but when it gets to the technical side, it took a while to bring everyone around. There are good sound reasons why we should be doing this,” says Crignano.

Two other proposed Toronto projects are innovating how trees, shrubs and other plants can be incorporated into vertical developments. They include The Plant on Queen Street West, a mixed-use 10-storey building by Windmill Developments and Curated Properties, and KING Toronto, which will integrate old buildings with new construction in a man-made ‘mountain village’ inspired by Moshe Sadfie’s Habitat 67 in Montreal.
The Plant, with its 78 residential suites (that have sold out), retail and office space, is based on the One Planet framework that follows 10 sustainability principles. The framework was created in 2003 by charity and social enterprise Bioregional, developed from planning the BedZED eco-village in London, England.

The Plant

The residences’ balconies will be oversized rooms for people to garden and grow vegetables, says Alex Spiegel, partner in charge of Windmill’s Toronto office. “Because big square balconies would block sunlight to the units below, The Plant’s are angled and cut back to let light in.” The suites will include in-kitchen micro-gardens to grow fresh herbs.

The Plant’s green roof will feature planter boxes stocked with flora to attract birds and butterflies and an exterior accent wall with vertically growing plants.

“We approach (the green roof) as a wonderful amenity that serves many purposes,” says Spiegel. “It collects stormwater, it will attract birds and bees, and it’s good for mental health.”

The green roof and vertical feature wall are components of The Plant’s integrated sustainable design and ‘Terrace to Table’ theme, with a focus on healthy living and urban agriculture. In addition to the balconies, there will be communal garden areas and a communal kitchen that doubles as a greenhouse, the latter of which will cultivate seeds and start new plants during the winter, as well as serving as a place where residents can prepare and preserve the vegetables they grow.

King Toronto will change the urban landscape, literally and figuratively, along King Street West between Spadina Avenue and Portland Street. It is a reimagining of the community-building potential of Habitat 67 in Montreal—a project that fascinated Westbank founder Ian Gillespie—and updates the glass and light innovations of Paris’s Maison de Verre. The 16-storey mixed-use development is still selling and marks a collaboration between Vancouver-based luxury real estate developer Westbank, Allied Properties and avant-garde architect Bjarke Ingels of Denmark’s BIG.
On his website, Ingels describes the condo as rising “sets of pixels extruded upwards,” while avoiding the footprint of the existing heritage buildings. Each “pixel” is the size of a room and will be rotated 45 degrees from the street grid to maximize light.
Its oversized balconies will be landscaped and provide tenants with the type of green space usually found in suburbs, with some common areas having potential use for urban farming. Irrigated planters of various sizes on the terraces have been designed and curated for their location and altitude. A cable trellis system will attach to the building in specific areas to facilitate vine growth on top of the exterior facade.

As cool as these types of projects are, they don’t come cheap. Vertical forests don’t make economic sense yet for many condo buildings because of the associated cost, says Crignano. Because the terraces need to be larger and specialized structural components and systems are required to accommodate the trees, added cost will be about $20 million to Designers Walk. But a boutique project such as that in a prime location in the upscale Annex and Yorkville neighbourhoods will be able to attract the type of buyers who can afford to pay a premium.

“A lot of buyers selling big homes with big front yards still want to maintain some outdoor space and do a bit of gardening,” says Crignano. “They want a place to step outside and not be confined to the indoors. We’re responding to market demand that’s been there for some time.”

But Alter is not convinced that vertical forests or green roofs are the best solution to greening our cities.
“They are a very high-maintenance item and they are heavy, so you have to put in more concrete and steel to support them,” he says. “They do help with the heat island effect and keep everything cooler, but I don’t believe they’ve lived up to the hype.”

That said, vertical forests are changing architecture, he admits. “Buildings used to be designed from how they’d look from the ground up. Now with drone and airplane views, roofs have become the nicest face of the building. Architects have started designing so buildings bend over and touch the ground and you can walk on them. Architects are now employing green wrapping in the way they used to use mirrored glass.”
Alter is not a fan of Milan’s Bosco Verticale, though, because “it takes a huge amount of concrete and steel to build the balconies needed to hold up those trees. One ton of cement puts out a ton (1.25 tons to be exact) of CO2 annually, while trees collect about 40 pounds of CO2 a year. It takes a very, very long time for a tree to justify its existence.”

There are other issues with vertical forests, he adds. “You have to have specially trained gardeners who can rappel down the building to look after them.” There’s also the danger posed if a limb breaks off and plummets to the street below.

However, Alter acknowledges there are psychological benefits to green roofs and vertical forests. “People who live in buildings with them love them. It is soothing; it does make you feel good. There’s no question that in terms of architecture and the comfort of people inside, they have been a huge success.”

The Plant Greenhouse/Canning Room

Beyond trees and balcony gardens, what else could be done to make condominiums more green? “I would cover buildings with mesh and let vines grow,” Alter says. “You plant them in the ground, they are low-maintenance and look fantastic. We should be designing to accommodate vines. They keep buildings cool in summer when they have leaves, and warm in winter, as the leaves fall off and the sun can hit the building. And contrary to belief, vines don’t damage buildings.”

For many, the concept has been a long time coming. Where, after all, would a vertical forest fit better than in a concrete jungle?

Getting to the Root of the Issue

Prior to working out the specs for Cityzen Development Group’s Designers Walk project, architect Brian Brisbin of Toronto’s Brisbin Brook Beynon travelled to the home of the vertical forest movement: Stefano Boeri Architetti’s Bosco Verticale project in Milan, Italy. Unable to tour the maintenance system and inner workings of Bosco Verticale, Brisbin took to Airbnb and temporarily moved in.

“I started pulling apart all of the panels in the floor, everywhere, to find out where all the systems were and how they did it,” he told the Globe & Mail. “Back home, a team was gathering around the Toronto project, including Paul Offierski, of the major nursery PAO Horticulture, and Marc Vanden Bussche of Vanden Bussche Irrigation,” the Globe writes. When Brisbin showed his findings to the team, Vanden Bussche “just started laughing,” Brisbin conveys. “He said, ‘None of that stuff’s from [Italy.] It’s entirely from Canada and the U.S.’ In other words, the inner workings were readily available.”

Raising the Roof

Testing Laboratory (GRIT Lab) at the University of Toronto’s John H. Daniels Faculty of Architecture, Landscape and Design investigates the environmental performance associated with green roofs, green walls and photovoltaic arrays.

The GRIT lab’s state-of-the-art facility is a leader in green-roof research, with 33 test beds, three green walls and a weather station. Sensors—270 of them connected to 5,000 linear feet of wiring—collect data on rainfall, humidity, flow rates, soil moisture, temperature, solar and wind every five minutes. This type of research has helped overcome early green-roof problems such as plants dying or green roofs turning brown due to a lack of irrigation, plant choice or design, or a combination of these.

GRIT’s Phase 1 covers 350 square metres of the Daniels Faculty roof. It tests and evaluates green-roof construction standards in line with Toronto’s Green Roof Bylaw with respect to stormwater retention, evaporative cooling, biodiversity and lifecycle cost. The test beds compare growing media type, depth, vegetation and irrigation regimes. Phase 2 explores the synergistic relationship between green roofs and PV arrays.

The National Research Council of Canada estimates a green roof can reduce air-conditioning use in a building by as much as 75%. They also help reduce air pollution and greenhouse gas emissions, according to the United States Environmental Protection Agency.
A green roof typically has several layers, including a waterproof membrane, root barrier, drainage layer, growing medium and plants (soil is too heavy to be used as a growing medium).

Since Toronto’s Green Roof bylaw was enacted on January 31, 2010, about 640 green roofs, covering more than 5 million square feet collectively, have been built.

The Ultimate Tree House

“We have enough steel, concrete and glass towers in our cities. But if you walk through the city and suddenly see a tower made of wood and plants, it will create an interesting contrast,” says Chris Precht of the Austria-based architectural firm of Precht.

While it has no firm development plan as yet, Precht’s dramatic Toronto Tree Tower design symbolizes an ecological system for wooden high-rises worldwide. Precht hopes the building will “be seen as a catalyst for future residential buildings that are more efficient to construct and more ecological to our environment than common construction methods.”

Toronto’s Tree Tower

Also inspired by Montreal’s Habitat 67, the 18-storey, cross-laminated timber project employs a modular building process, where prefabricated and precut CLT panels are assembled to modules off-site at an indoor facility. Once the foundation, ground floor and base core are complete, all modules, including fixtures and finishes are delivered to the site and craned into place.

Large terraces would be planted with trees, shrubs and vegetable gardens.
Precht has also developed another fully prefabricated modular structure called Farmhouse, “an attempt to reconnect people in the city with the process of growing our food,” the company notes. “In the next 50 years more food will be consumed than in the last 10,000 years combined, and 80% will be eaten in cities. It is clear that we need to find an ecological alternative to our current food system.

“Buildings already create a large amount of heat, which can be reused for plants like potatoes, nuts or beans to grow,” Precht adds. “A water-treatment system filters rain- and greywater, enriches it with nutrients and cycles it back to the greenhouses. The food waste can be locally collected in the building’s basement, turned into compost and reused to grow more food.”


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