Architect Michael Green presents an interesting riddle: why are buildings made of wood only a few stories high when trees found in nature are remarkable for their height?
Speaking in session 7 of TED2013, Green shares his deep love of wood — which he first discovered from his grandfather, a woodworker who taught him to “honor a tree’s life by making it as beautiful as you possibly can.” Now, Green designs buildings made of wood and he notices that people have an usual relationship to wooden walls, columns and ceilings.
“They hug it. They touch it,” he says. ”Just like snowflakes, no two pieces of wood can be the same anywhere on earth. I’d like to think that wood gives mother nature fingerprints in our buildings.”
However, building codes currently limit wood buildings to four stories high. And this needs to change, says Green. He proposes that we build skyscrapers out of wood. For the last century, tall buildings have been crafted of steel and concrete — but the green house gas emissions of these materials are huge. As Green notes, 3% of world’s energy goes into the making of steel and 5% goes into the making of concrete. While most people think of transportation as the main villain when it comes to CO2 emissions, building is actually the true top offender — accounting for 47% of CO2 emissions.
Wood, on the other hand, grows by the power of sun, giving off oxygen and storing carbon dioxide. That carbon dioxide is released when the tree falls and decomposes. By building with wood, we could sequester carbon dioxide. Green says that building with 1 cubic meter of wood stores 1 ton of CO2.
“We have an ethic that the earth grows our food,” says Green. “We should move toward an ethic that the earth should grow our homes.”
Green is not talking about building 20- and 30-story buildings with 2x4s. He explains the technology that has been created to form rapid growth trees into mass timber panels. There is a flexible system to build with these huge panels.
Now, on to the obvious question: what about fires?
Green points out that mass timber panels are extremely dense and, thus, don’t catch fire easily — it’s the same principle that makes a log hard to burn. And when a fire does catch, it moves slowly and behaves predictably, allowing for uniform fire safety measures to be put in place.
Another question that people often ask of his system: what about deforestation?
Green introduces us to sustainable forestry, and shares that enough wood grown in North America every 13 minutes for a 20 story building.
“This is the first new way to build a skyscraper in 100 years or more,” says Green. He notes that people were terrified to walk under the first skyscraper, but that the perception of these buildings as unsafe began to change with the building of the Eiffel Tower.
“I’m looking for an Eiffel Tower moment,” says Green. ”The engineering of this is the easy part. It’s about changing the scale of imagination … Mother nature holds the patent.”