How Toronto could lead the wooden skyscraper revolution

The winner of George Brown College’s Arbour Design Competition was this scheme from Moriyama & Teshima and Acton Ostry. The structural system is so cost-effective, it could transform how buildings are built. (Courtesy of George Brown College)

A Sidewalk Talk Q&A with architect and designer Luigi Ferrara on the Arbour — a 12-story wood building for George Brown College’s waterfront campus.

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Toronto’s skyline tells the story of a postwar high-rise boom powered by a cheap new material: concrete. To Luigi Ferrara, it’s also a testament to the Italian immigrant workers — among them, his family relations — who actually did the construction. “Toronto, I think, has the highest amount of concrete high-rise buildings of any city in the world,” he says. “It’s because people brought those skills, and they were able to deliver.”

Ferrara, who is dean of the Centre for Arts, Design, and Information Technology at George Brown College, is taking the family tradition in a new direction, advocating for a far more sustainable material to redefine Toronto’s future: mass timber. A type of engineered wood that is structurally as strong as steel but far more sustainable, mass timber has made tall wooden buildings possible — and they’re cropping up all over the world, from the Cube in London (10 stories) to the Tree in Norway (14 stories) to Brock Commons in Vancouver (18 stories).

George Brown College recently held a competition called the Arbour to design a 12-story wood building for its waterfront campus, which will host classrooms, a child care facility, and a new Tall Wood Research Institute. While all four proposals point to fascinating ways the technology could evolve, the winning proposal by Moriyama & Teshima and Acton Ostry Architects was not only cost-effective, and thus potentially replicable at scale, but remarkable in the extent to which it used wood — from the structural core to the warm interiors.

“It’ll be like living in a violin; the building resonates around you with the wood,” says Ferrara. “It’s going to be quite symphonic in that sense.”

Ferrera spoke to Sidewalk Talk about what’s so “revolutionary” about mass timber, how the Arbour (and the Tall Wood Institute) will push this building technology forward, and what it will feel like to live in a city built of wood.

What inspired you to pursue a tall wood building for the Arbour?

At George Brown, we rent mass-timber warehouse buildings from the 19th century. What’s wonderful about the buildings is you see the wood, it surrounds you, it’s very beautiful, it’s very warm to the touch. They’re also very flexible, not only in terms of what you can do to change them over time, but how you can interact with them as a human being. And so, the ambition with the Arbour was to go back to a tradition of building that has a more humane quality to it.

And that couples with the need that we have in the 21st century to change our building stock, to build in a different way to have our greenhouse gas emissions be reduced. The building sector is approximately 50 percent of greenhouse gas emissions, and so all new buildings should be trying to explore and understand how to build in a way that reduces impact.

The design from Provencher Roy Architects (with Arup Engineering and Turner Fleischer Architects) proposed a staggered truss technology, which allows for extreme flexibility of use. ”They built these two-story trusses, and staggered them, and that created a super-structure for the building. You could then place floors in between the two-story volumes,” says Ferrera. “It made for a dramatically beautiful and flexible building. If one year we wanted to have a basketball court in there, we could have a basketball court, and then the next year you could put two floors of offices. So it really was future-proofed from a planning perspective.” (Courtesy of George Brown College)

With the Arbour, you’re undertaking a more ambitious energy goal than LEED gold. Can you talk about what you’re looking to achieve?

So with this building, we’re trying to move towards a net-positive standard, where we create more energy than we consume. That’s going to be extremely challenging, because the climate zone that we’re in in Canada has high energy demand in both winter and summer. With this building, we’re hoping to use really intelligent passive design to reduce the amount of energy required by the building. And then we want to use the latest and most appropriate active technologies, like solar panels, to generate clean energy.

A lot of these techniques, such as passive design, it’s not like they’re unique to a tall wood building. You could apply these methods to a different type of construction.

Yes. What the wooden building does is it sequesters a lot of carbon. It has lower energy embodiment in its production than concrete or steel. Steel has an incredible amount of energy that goes into just making it, whereas wood is harvested and dried and then just cut, basically. And concrete also has a lot of embedded energy, though there are certain types of technologies that can make it more sustainable, but ultimately wood is still less carbon intensive.

A super-insulated wooden building works extremely well passively. And the net positive doesn’t really have to do with concrete, per se, it’s really how much energy it takes you to run your building and how much energy you’re able to generate on-site, so how much energy are you able to save. The passive strategy is one where you don’t use a lot of mechanical systems, but use natural systems instead, like conduction of air and absorption of sunlight, to create a building that doesn’t need a lot of energy to run and operate.

In the case of our building, there is the opportunity to use excess heat from another building, to exchange it, and bring it into our building. So it’s a way of understanding buildings not in isolation, but in an ecosystem, and trying to figure out how to best design that ecosystem.

Is there anything different about making a tall wood building?

One of the reasons concrete has been such a powerful material since the Roman times is because it has tremendous properties; it doesn’t burn, it resists weather, it’s an incredible material. With wood, wood has tremendous flexibility. It has the capacity to be cut very easily, and joined together very easily, and to be taken apart and put back together. That’s very difficult in a concrete building because it’s a wet process; a wooden building is a dry process, in essence.

The scheme by Patkau Architects (with MacLennan Jaunkalns Miller Architects) proposed a wooden building with a glass building around it. “The glass building integrated photovoltaics that created a lattice, almost like leaves covering a tree creating shade,” says Ferrera. “So this glass-skin would absorb and collect energy to power the building, but then your building had an external walkway that protected the internal wooden building inside, and that air buffer mitigated the temperature. The inside wooden building was made with this spectacular kind of mass timber truss system, very much like Tudor houses.” (Courtesy of George Brown College)

But its dryness is also the challenge. Wood doesn’t fair well when it’s exposed to water, because it will expand and contract and it will crack. Wood is susceptible to fire, so there are challenges in creating wood buildings, and especially in creating tall wood buildings. But on the other hand, wood burns slower; it can char and then stop burning right through, which you’ve seen any time you’ve thrown a log into a fireplace. So that makes it, in a way, stronger than steel, because steel will melt and then will start to come apart compositionally.

So there are advantages and disadvantages and you need to design and plan to accommodate for the weaknesses and the strengths.

You will need a site-specific exemption to build the Arbour, because it’s taller than Toronto code permits. How tall can wood buildings go currently?

In Ontario, previously wood buildings were only allowed up to three stories — which was very problematic. You either had to make a tall concrete building, or you had to make single-family houses and small little wooden buildings.

In the last few years the dramatic change was pushed through that allowed them to be created up to six stories. This opening up of the code to allow for six-story wood buildings means that it becomes affordable to build a type of housing that was very traditional in the 19th century, but has not been really been built in the 20th century, which is mid-rise housing. It enables you to build buildings that are six-to-eight stories tall, and create a different type of urban density that’s more amenable to public transit, that is more sustainable in terms of urban design.

So right now we can get to six stories. What we’re trying to do is to push that even further.

What is your hope for this building? Do you hope that it plays a role in changing perceptions, not just in terms of building code but in terms of housing?

We have some pretty ambitious goals. We want to demonstrate that buildings in wood can be built safely, and that we can create the solutions in terms of protection of the wood, the fire safety in the wood, the efficiencies of construction.

There’s many different systems that can be developed using the tall wood technology, and one of those systems is going to become the one that’s most successful, most affordable, most easy to build, that delivers the best performance, and has the greatest flexibility. Then over time, people will start to use it.

“The Shigeru Ban design had this shape that was very unusual, but the structural logic was very simple,” says Ferrera. “There were these wooden beams, radiating from a wooden-concrete core, that were doweled to vertical rims, almost like a giant basket. It had this double skin that really protected the interior spaces; in other words, it used passive design principles. It also had a solar chimney that would suck the hot air out, or trap the hot air in. So the sun would come in, it would heat the concrete floor and the core, then the core would release the heat in the evening, balancing the overall system.”

So we want to pioneer what that system is. Now already, our doing this building has gotten many of our corporate partners thinking: maybe we need to get into creating the mass timber members and having a plant that does that. They want to follow our construction process so that they can learn and see what are the pitfalls.

So we are opening up our process for people to follow, and we’re going to be putting out information about what we’ve learned through the process. We’re going to be monitoring the building after to show how it’s working, whether the solutions that we developed really deliver what they said they would. With that knowledge and information, other people can be armed to make buildings like this, or to improve and solve the mistakes that we made in our process.

Are you going to have to train construction workers to be able to build this structure?

When buildings were made of wood in the 19th century, and then all of a sudden the concrete industry was developed, people had to be trained on: how do you pour concrete, how do you lay these rods of steel?

These buildings are planned using something called building information modeling, then they’re computer cut, and they arrive on the site and are rapidly erected. It’s a different set of skills and a different set of knowledge that you need. That’s one of the reasons we’re creating the Tall Wood Research Institute, to create a new generation of people in the construction, engineering, and development industry that can plan these buildings.

I want to get into the international design competition for the Arbour. What stuck out about the winning proposal?

The scheme that won, Moriyama & Teshima and Acton Ostry Architects’ scheme, created super-insulated facades on the north and south, and double envelopes on the east and west side with solar chimneys. They would capture the morning sun and redistribute that energy as needed, but then capture the setting sun, and then reuse it as needed. So the building was imagined as a living system, taking advantage of the orientation.

The structural system of their project was incredibly clever and the flexibility was great because you could take away parts of the floor, or put them back as needed. You could change the partitions over time as well. So you could have one half of the building totally open, you could use it almost as a banquet room, and then you could divide it with these partitions so that you would turn it into five classrooms later.

An interior rendering of the Arbour, the winning proposal by Moriyama & Teshima and Acton Ostry Architects. (Courtesy of George Brown College)

The interesting thing about the solution was that they didn’t need any concrete, unlike most tall wood buildings, which are hybrid. Their system was so cost-effective that it could easily be migrated to be used for condominiums.

And you are really trying to create something that could be repeated and built on a wide scale.

That’s one of the reasons we chose the Moriyama & Teshima and Acton Ostry scheme as the winner, because we feel that if we can demonstrate this solution, it will transform how buildings are built. Residential and commercial buildings, they have to watch their pennies. So you need a system that is really functional, simple, easy to build, which doesn’t take too much space.

The potential for these buildings to bring a sense of nature back into cities is really exciting.

It’s important how these buildings are going to look in the city. They’re going to create a different and new look. Down at the waterfront, when I’m looking at all the condos, there is a look to the buildings that is lacking in warmth. It’s what most of the public feels unhappy about with most modern construction: that it’s too mechanical, it’s too repetitive, and it doesn’t have a human quality.

I think the building that we’re going to build is going to show how much of a human quality you can inject back into buildings, because you’ve changed back to this different structural system. I think that it’s going to stand apart from the current buildings that are there, and that’s going to be a big signal about what a 21st-century architecture might look like.

May 11, 2018