Why we should build wooden skyscrapers

Building a skyscraper? Forget about steel and concrete, says architect Michael Green, and build it out of … wood. As he details in this intriguing talk, it's not only possible to build safe wooden structures up to 30 stories tall (and, he hopes, higher), it's necessary.

This is my grandfather.

And this is my son.

My grandfather taught me to work with wood

when I was a little boy,

and he also taught me the idea that

if you cut down a tree to turn it into something,

honor that tree's life and make it as beautiful

as you possibly can.

My little boy reminded me

that for all the technology and all the toys in the world,

sometimes just a small block of wood,

if you stack it up tall,

actually is an incredibly inspiring thing.

These are my buildings.

I build all around the world

out of our office in Vancouver and New York.

And we build buildings of different sizes and styles

and different materials, depending on where we are.

But wood is the material that I love the most,

and I'm going to tell you the story about wood.

And part of the reason I love it is that every time

people go into my buildings that are wood,

I notice they react completely differently.

I've never seen anybody walk into one of my buildings

and hug a steel or a concrete column,

but I've actually seen that happen in a wood building.

I've actually seen how people touch the wood,

and I think there's a reason for it.

Just like snowflakes, no two pieces of wood

can ever be the same anywhere on Earth.

That's a wonderful thing.

I like to think that wood

gives Mother Nature fingerprints in our buildings.

It's Mother Nature's fingerprints that make

our buildings connect us to nature in the built environment.

Now, I live in Vancouver, near a forest

that grows to 33 stories tall.

Down the coast here in California, the redwood forest

grows to 40 stories tall.

But the buildings that we think about in wood

are only four stories tall in most places on Earth.

Even building codes actually limit the ability for us to build

much taller than four stories in many places,

and that's true here in the United States.

Now there are exceptions,

but there needs to be some exceptions,

and things are going to change, I'm hoping.

And the reason I think that way is that

today half of us live in cities,

and that number is going to grow to 75 percent.

Cities and density mean that our buildings

are going to continue to be big,

and I think there's a role for wood to play in cities.

And I feel that way because three billion people

in the world today, over the next 20 years,

will need a new home.

That's 40 percent of the world that are going to need

a new building built for them in the next 20 years.

Now, one in three people living in cities today

actually live in a slum.

That's one billion people in the world live in slums.

A hundred million people in the world are homeless.

The scale of the challenge for architects

and for society to deal with in building

is to find a solution to house these people.

But the challenge is, as we move to cities,

cities are built in these two materials,

steel and concrete, and they're great materials.

They're the materials of the last century.

But they're also materials with very high energy

and very high greenhouse gas emissions in their process.

Steel represents about three percent

of man's greenhouse gas emissions,

and concrete is over five percent.

So if you think about that, eight percent

of our contribution to greenhouse gases today

comes from those two materials alone.

We don't think about it a lot, and unfortunately,

we actually don't even think about buildings, I think,

as much as we should.

This is a U.S. statistic about the impact of greenhouse gases.

Almost half of our greenhouse gases are related to the building industry,

and if we look at energy, it's the same story.

You'll notice that transportation's sort of second down that list,

but that's the conversation we mostly hear about.

And although a lot of that is about energy,

it's also so much about carbon.

The problem I see is that, ultimately,

the clash of how we solve that problem

of serving those three billion people that need a home,

and climate change, are a head-on collision

about to happen, or already happening.

That challenge means that we have to start thinking in new ways,

and I think wood is going to be part of that solution,

and I'm going to tell you the story of why.

As an architect, wood is the only material,

big material, that I can build with

that's already grown by the power of the sun.

When a tree grows in the forest and gives off oxygen

and soaks up carbon dioxide,

and it dies and it falls to the forest floor,

it gives that carbon dioxide back to the atmosphere or into the ground.

If it burns in a forest fire, it's going to give that carbon

back to the atmosphere as well.

But if you take that wood and you put it into a building

or into a piece of furniture or into that wooden toy,

it actually has an amazing capacity

to store the carbon and provide us with a sequestration.

One cubic meter of wood will store

one tonne of carbon dioxide.

Now our two solutions to climate are obviously

to reduce our emissions and find storage.

Wood is the only major material building material

I can build with that actually does both those two things.

So I believe that we have

an ethic that the Earth grows our food,

and we need to move to an ethic in this century

that the Earth should grow our homes.

Now, how are we going to do that

when we're urbanizing at this rate

and we think about wood buildings only at four stories?

We need to reduce the concrete and steel and we need

to grow bigger, and what we've been working on

is 30-story tall buildings made of wood.

We've been engineering them with an engineer

named Eric Karsh who works with me on it,

and we've been doing this new work because

there are new wood products out there for us to use,

and we call them mass timber panels.

These are panels made with young trees,

small growth trees, small pieces of wood

glued together to make panels that are enormous:

eight feet wide, 64 feet long, and of various thicknesses.

The way I describe this best, I've found, is to say

that we're all used to two-by-four construction

when we think about wood.

That's what people jump to as a conclusion.

Two-by-four construction is sort of like the little

eight-dot bricks of Lego that we all played with as kids,

and you can make all kinds of cool things out of Lego

at that size, and out of two-by-fours.

But do remember when you were a kid,

and you kind of sifted through the pile in your basement,

and you found that big 24-dot brick of Lego,

and you were kind of like,

"Cool, this is awesome. I can build something really big,

and this is going to be great."

That's the change.

Mass timber panels are those 24-dot bricks.

They're changing the scale of what we can do,

and what we've developed is something we call FFTT,

which is a Creative Commons solution

to building a very flexible system

of building with these large panels where we tilt up

six stories at a time if we want to.

This animation shows you how the building goes together

in a very simple way, but these buildings are available

for architects and engineers now to build on

for different cultures in the world,

different architectural styles and characters.

In order for us to build safely,

we've engineered these buildings, actually,

to work in a Vancouver context,

where we're a high seismic zone,

even at 30 stories tall.

Now obviously, every time I bring this up,

people even, you know, here at the conference, say,

"Are you serious? Thirty stories? How's that going to happen?"

And there's a lot of really good questions that are asked

and important questions that we spent quite a long time

working on the answers to as we put together

our report and the peer reviewed report.

I'm just going to focus on a few of them,

and let's start with fire, because I think fire

is probably the first one that you're all thinking about right now.

Fair enough.

And the way I describe it is this.

If I asked you to take a match and light it

and hold up a log and try to get that log to go on fire,

it doesn't happen, right? We all know that.

But to build a fire, you kind of start with small pieces

of wood and you work your way up,

and eventually you can add the log to the fire,

and when you do add the log to the fire, of course,

it burns, but it burns slowly.

Well, mass timber panels, these new products

that we're using, are much like the log.

It's hard to start them on fire, and when they do,

they actually burn extraordinarily predictably,

and we can use fire science in order to predict

and make these buildings as safe as concrete

and as safe as steel.

The next big issue, deforestation.

Eighteen percent of our contribution

to greenhouse gas emissions worldwide

is the result of deforestation.

The last thing we want to do is cut down trees.

Or, the last thing we want to do is cut down the wrong trees.

There are models for sustainable forestry

that allow us to cut trees properly,

and those are the only trees appropriate

to use for these kinds of systems.

Now I actually think that these ideas

will change the economics of deforestation.

In countries with deforestation issues,

we need to find a way to provide

better value for the forest

and actually encourage people to make money

through very fast growth cycles --

10-, 12-, 15-year-old trees that make these products

and allow us to build at this scale.

We've calculated a 20-story building:

We'll grow enough wood in North America every 13 minutes.

That's how much it takes.

The carbon story here is a really good one.

If we built a 20-story building out of cement and concrete,

the process would result in the manufacturing

of that cement and 1,200 tonnes of carbon dioxide.

If we did it in wood, in this solution,

we'd sequester about 3,100 tonnes,

for a net difference of 4,300 tonnes.

That's the equivalent of about 900 cars

removed from the road in one year.

Think back to that three billion people

that need a new home,

and maybe this is a contributor to reducing.

We're at the beginning of a revolution, I hope,

in the way we build, because this is the first new way

to build a skyscraper in probably 100 years or more.

But the challenge is changing society's perception

of possibility, and it's a huge challenge.

The engineering is, truthfully, the easy part of this.

And the way I describe it is this.

The first skyscraper, technically --

and the definition of a skyscraper is 10 stories tall, believe it or not —

but the first skyscraper was this one in Chicago,

and people were terrified to walk underneath this building.

But only four years after it was built,

Gustave Eiffel was building the Eiffel Tower,

and as he built the Eiffel Tower,

he changed the skylines of the cities of the world,

changed and created a competition

between places like New York City and Chicago,

where developers started building bigger and bigger buildings

and pushing the envelope up higher and higher

with better and better engineering.

We built this model in New York, actually,

as a theoretical model on the campus

of a technical university soon to come,

and the reason we picked this site

to just show you what these buildings may look like,

because the exterior can change.

It's really just the structure that we're talking about.

The reason we picked it is because this is a technical university,

and I believe that wood is the most

technologically advanced material I can build with.

It just happens to be that Mother Nature holds the patent,

and we don't really feel comfortable with it.

But that's the way it should be,

nature's fingerprints in the built environment.

I'm looking for this opportunity

to create an Eiffel Tower moment, we call it.

Buildings are starting to go up around the world.

There's a building in London that's nine stories,

a new building that just finished in Australia

that I believe is 10 or 11.

We're starting to push the height up of these wood buildings,

and we're hoping, and I'm hoping,

that my hometown of Vancouver actually potentially

announces the world's tallest at around 20 stories

in the not-so-distant future.

That Eiffel Tower moment will break the ceiling,

these arbitrary ceilings of height,

and allow wood buildings to join the competition.

And I believe the race is ultimately on.

Thank you.

(Applause)