Take a look at this city skyline.
For the most part, these skyscrapers are made out of two materials.
Concrete and steel,
which are great for building but not so great for the climate.
But what if you added … wood?
Wood is one of the oldest building materials.
It’s made out of carbon, sucked up from the atmosphere.
For most of history, we couldn’t build wood structures higher than a few stories.
Until now, thanks to a new technology called cross-laminated timber.
So what could wooden skyscrapers mean for our climate?
Steel and concrete take a lot of energy and heat to produce —
Here’s the carbon footprint for each of them.
Well-managed timber, on the other hand, is kind of the opposite.
But how does that work?
Take these two forests.
These trees are sucking a lot of carbon dioxide out of the atmosphere, and turning that carbon
into wood.
After 80 years, this forest gets cut and this one keeps growing.
As trees get old, they start to suck up carbon a little slower,
and some eventually die and decompose.
Meanwhile, the cut forest is replaced with new saplings.
The cut trees are turned into lumber, making pretty much anything built from wood a kind
of carbon storage unit.
But there are some big assumptions in this ideal wood-fueled scenario.
Let’s say, for example, that forest we turned into lumber isn’t replanted.
Or maybe it’s unhealthy, poorly managed, or burns in a wildfire before it can be logged.
And the let-grow forest has countless ecological and watershed benefits that this accounting
just doesn’t capture.
But the point is:
under the right circumstances, and at the right scale,
tall wood buildings could be great for the climate.
Right now in the U.S., most wood buildings still aren’t taller than six stories.
But cross-laminated timber could change that.
It's strong, simple to build with, and easy to make.
So easy, I made some myself.
I’m starting with these 2 by 6 boards —
the kinds of boards you can find at Home Depot.
Then, they’re cut, stacked Jenga style, and glued together in a press.
In the end, you get sheets of wood, like this.
Now obviously I’m not going to get very far here because this is... tiny.
The real stuff is massive, and built in big factories with high standards.
But the point is, with simple materials like boards and glue, you can build towers!
At least, that’s what they’re doing in Canada or Europe 😉
Susan Jones is trying to make CLT happen in the U.S.
This is her CLT house.
When she built it in 2015, it was one of the first in the country.
“We like to joke that this is not a building, this
is a
carbon sink.
Another benefit to cross-laminated timber: it can make use of wood that otherwise would’ve
been wasted.
Many states in the West are trying to thin overgrown or diseased forests, which act like
tinder for wildfires.
Many of those tiny trees wouldn’t have a traditional market.
But with cross-laminated timber, you can actually put those waste products to work.
Take this wall in Susan’s kitchen.
This middle layer came from a six-inch wide tree that was killed by a blue beetle infestation.
A dead tree, put to use as a binder layer.
“If we do this right — and I can’t emphasize that enough — if we do this right, then
the forests will be healthier, and a lot of that carbon is going to be stored in buildings,
like this and bigger scale.”
Slowly but surely, the barriers surrounding mass timber are starting to come down.
After Susan built her house,
she was picked to serve on a committee to write the new international codes for tall
wood buildings.
Tall wood buildings might sound like a fire hazard.
Part of the committee’s job was proving they’re sturdy and fire resistant.
“We built this two-story structure, and then burned it down five times
— tried to burn!
It did not burn down!
But you could feel the heat…
The structure was completely intact…
after four hours of burning with no sprinklers.”
Now, a supply chain is growing,
along with the number of CLT schools, churches, affordable housing projects, and offices
— it’s even being used to build Adidas’s new U.S. headquarters!
“When you introduced concrete in the early part of the 20th century, it was also a new
technology.
We’re just introducing a new one, and it’s going to be commonplace.”
Cities are growing around the world.
And maybe the buildings themselves could turn into a climate solution.