CLT: Sending Wood to the Environmental Rescue

Over the past four months, we’ve considered the many impacts of using wood and mass timber in construction. We looked at what using more wood could mean for our forests, our economies, our mills and the people who work there. This last article takes a global look at how wood construction impacts the environment. Mass timber structures are strong, beautiful, durable, affordable and safe. But are they the right choice for the planet?

Check any newsstand and you’ll see headlines filled with concern over the environment. And it’s not just scientists who are alarmed; even Rolling Stone magazine weighed in with a recent article warning us about the dire consequences of our carbon emissions.

Is it too late? Can wood construction do anything to help save our planet?¹

WOOD HOLDS THE POTENTIAL

Global construction is booming. One study² estimates that an additional 82 billion square meters/900 billion square feet will be built worldwide by 2030. That’s an additional 60 percent of the world’s current total.

This growth will come at a cost, since the construction industry is a huge consumer of energy. CO₂ emissions from the Canadian construction industry rose by more than 40 percent between 1990 and 2013.³ In the United States, the building sector alone accounted for 41 percent of primary energy consumption in 2010.⁴

While some see these statistics as dismal, it also means that we as an industry have the extraordinary opportunity to reverse the trend of greenhouse gas emissions—simply by changing the ways in which we build.

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CARBON BENEFITS

There are many reasons why people consider wood to be a better building material than concrete and steel, and carbon is at the top of the list. By using more wood, we can reduce CO₂ emissions and fossil fuel consumption because wood has lower energy consumption and carbon emissions than other building materials.⁵

Landmark research⁶ published in 2013 by researchers at Yale and the University of Washington found that using more wood in construction instead of steel or concrete could result in a 14 to 31 percent reduction in global greenhouse gas emissions and a 12 to 19 percent reduction in fossil fuel consumption. Most of the carbon savings would come from avoided emissions (using wood in place of steel and concrete); some of the fossil-fuel savings would come from the fact that scrap wood can be burned for energy.

The study also found that when wood was harvested from sustainably managed forests and used for construction, there were more carbon benefits realized than if the trees had just been left standing. In other words, more CO₂ could be sequestered in the products and the built structures together than in an unharvested forest.

For every ton of wood used in place of other structural materials, we avoid 2.1 tons of carbon emissions.⁷ And the carbon stays put. A typical 216-square-meter/2,400-square-foot wood-frame house stores 28.5 tons of CO₂ in the wood. That’s the same as neutralizing the emissions from a small car for seven years.⁸

ENERGY EFFICIENCY

Wood is also an energy-efficient building material. When you consider wood’s heat insulation properties and the fact that CLT panels can be manufactured to precise tolerances for better energy efficiency, the benefits add up.

More than 48 percent of total building energy consumption is due to the use of heating and cooling equipment⁹ so potential for improvement is high. The United Nations Energy Programme¹⁰ estimates that energy consumption in buildings could be reduced by 30 to 80 percent using proven and commercially-available technologies. We think wood is the answer.

CLT and other mass timber building systems provide thermal mass, which can reduce cooling and heating loads and lower building energy use. And these energy savings add up year after year, reducing energy consumption and greenhouse gas emissions throughout the life of the building.

LET’S GET STARTED

Awareness of CLT and heavy timber design is still relatively low among the design community, but the carbon benefits of wood construction are helping these building systems get more attention.

Increased use of wood as a substitute for concrete and steel will help mitigate carbon issues, reduce fossil fuel consumption and utilize a completely renewable resource.

As one expert put it, “There is no downside whatsoever to using more wood for buildings.”