Thought folks might be interested in this piece from Popular Science here.
Why the sudden interest in wood? Compared with steel or concrete, CLT, also known as mass timber, is cheaper, easier to assemble, and more fire resistant, thanks to the way wood chars. It’s also more sustainable. Wood is renewable like any crop, and it’s a carbon sink, sequestering the carbon dioxide it absorbed during growth even after it’s been turned into lumber. Waugh Thistleton estimates that the wood in Stadthaus stores 186 tons of carbon while the steel and concrete for a similar, conventionally built tower would have generated 137 tons of carbon dioxide during production. Wood nets a savings of 323 tons.
Demographers predict that the planet’s urban citizenry will double in 36 years, increasing the demand for ever-taller structures in ever-denser cities. Whether architects and construction firms build those towers from unsustainable materials like steel and concrete or employ new materials like CLT could make a huge difference in the Earth’s health. Put differently, the world’s urban future may just lie in its oldest building material.
But the biggest driving force behind the turn toward wood is a growing awareness among architects and developers about their field’s contribution to climate change. “Our industry leads all others in terms of its impact on the planet and human health,” Waugh says. Concrete and steel require enormous amounts of energy to produce and transport, generating more than a ton of carbon dioxide per ton of steel or concrete.
Wood, on the other hand—even engineered wood like CLT, which requires additional energy to cut and press into sections—is far more environmentally friendly. According to Wood for Good, an organization that advocates for sustainable wood construction, a ton of bricks requires four times the amount of energy to produce as a ton of sawn softwood; concrete requires five times, steel 24 times, and aluminum 126 times. Wood also performs better: It is, for example, five times more insulative than concrete and 350 times more so than steel. That means less energy is needed to heat and cool a wood building.
When CLT is used to build high-rise towers, the carbon savings can be enormous. The 186 tons of carbon locked into Stadthaus are enough to offset 20 years of its daily operations, meaning that for the first two decades of its life, the building isn’t carbon neutral—it is actually carbon negative. Rather than producing greenhouse gases, Stadthaus is fighting them.