Wood products are both renewable and naturally low in embodied carbon. They are a “right-now” solution that meets performance and sustainability objectives for the built environment.  

There are a myriad of ways a building’s embodied carbon emissions can be reduced. In addition to designing in more energy efficiency, material choices can significantly impact the environmental impacts of the structure. Using wood products not only reduces the building’s greenhouse gas emissions but is also the only structural building material derived from a renewable resource. 

The United States is global leader when it comes to managing our forests and the ecosystems, wildlife, and communities that depend on them. Our forestry practices are sustainable – a cycle of growing, harvesting, and replanting while protecting water, wildlife, and recreation, and simultaneously generating forest products which provide an economic incentive for landowners to keep forests as forests. 

Measuring Carbon

When thinking about the carbon impacts of a building project, it is important to differentiate between two different “types” of carbon that can be measured:  

“Embodied Carbon” measures the Global Warming Potential (GWP) based on the emissions associated with the extraction, transportation, manufacture, use, and end-of-life outcome for a material.  

“Stored Carbon,” also called “biogenic carbon,” measures the carbon that is organically stored in wood products from photosynthesis, during their growth, sequestering carbon from the atmosphere into the substance of the tree. 

50 percent Carbon by Dry Weight

Depending on end-use and service life conditions, wood products can store carbon for many decades or longer, providing long-term environmental, carbon-storing benefits.  For example, the Horyuji Temple in Japan is one of the world’s oldest wooden buildings and was constructed in 607 A.D. 

Specifying structural wood and wood finishes in buildings ensures the carbon being stored in the product does not enter the atmosphere during the lifetime of the structure—even longer if the wood is reclaimed/reused.  

A Comparative Whole Building Life Cycle Assessment Study

A recent study compared the life cycle impacts of an 8-story above-grade, nonresidential structure with 3 stories of below-grade parking located in the Pacific Northwest. Three construction material scenarios were evaluated: a traditional reinforced concrete building, two using cross-laminated timber (CLT) and glulam, one using gypsum wallboard, and one using exposed wood for fire resistance. 

The study considers extraction, transportation, manufacturing, and construction transportation and installation, the “embodied carbon” impacts of the project scenarios. The study found: 

• An average of a 26.5% reduction in Global Warming Potential was observed in the two CLT-glulam scenarios. That outcome was without taking into consideration the stored carbon in the building materials. 
• The embodied fossil energy was 8% lower in the CLT-glulam scenarios.
• An additional 1,556 to 2567 tons of biogenic carbon is stored in the CLT-glulam building scenarios with and without gypsum wallboard protection, respectively. 

Wood products are resilient, reliable, low-impact building materials.