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Buildings, and the materials they are made of, have a significant impact on the environment in which they’re constructed. Buildings consume nearly half the energy produced in the United States, use three-quarters of the electricity and account for nearly half of all carbon dioxide (CO₂) emissions. The magnitude of their effects is the driving force behind many initiatives to improve tomorrow’s structures—from energy regulations and government procurement policies, to green building rating systems and certification programs.

With growing pressure to reduce the environmental impact of buildings, architects and engineers are looking beyond operational performance to the role structural materials such as wood can play in achieving a project’s sustainability goals.

Sustainability: A Full Lifecycle View

Understanding a material’s environmental impacts at every stage of its lifecycle is essential. Lifecycle assessment (LCA) studies, which adhere to a standardized set of international guidelines, consistently show that wood has a favorable environmental profile compared to other common materials like steel or concrete. Wood grows naturally, is renewable and offers advantages from a carbon footprint perspective. It is also durable, adaptable and, according to research from FPInnovations, can have positive impacts on a building’s occupants including improved attention and focus, lowered stress levels and greater creativity.

Responsible Sourcing and Production

While the manufacturing stage typically accounts for the largest portion of embodied energy and emissions associated with the lifecycle of a building product, it is also an area where wood consistently outperforms steel and concrete. Wood is one of the few building materials that has third-party-verified certification programs in place to demonstrate that products come from a responsibly-managed resource. As of 2015, more than 500 million acres of forest in the United States and Canada were certified under one of the four internationally recognized programs used in North America.

Producing lumber is straightforward once the wood is harvested. At a lumber mill, bark is removed and logs are sawn. The logs are trimmed to produce smooth, parallel edges, cut to square and precise lengths, dried and then planed. Finally, the lumber is grade stamped and packaged. Mass timber products, which have structural performance characteristics that allow them to compete with steel or concrete in many applications, also require the use of lamination, kiln-drying or moisture-resistant adhesives.

Transporting and Building with Wood

According to the Athena Sustainable Materials Institute, which specializes in LCA, the on-site construction stage is similar to an additional manufacturing step where individual products, components and sub-assemblies come together in the manufacture of a building. Although transportation may comprise a significant portion of the impacts at this stage, trees grow abundantly across North America and wood can often be sourced locally, reducing transport costs. It also weighs less than other structural materials, further reducing the energy required to move it.

LCA helps ensure that all aspects of energy use are considered. It accounts for the effects of the transportation mode and not just the distance. For example, a product traveling long distances using highly efficient transportation can produce a smaller carbon footprint than a nearby product that travels inefficiently.

End-of-Life Disposal, Reuse and Recycling

Although demolition signifies the end of a building’s lifecycle, it is not the end for building materials, which still face disposal, recycling or reuse. For obvious reasons, recycling and reuse are encouraged and rewarded by green building rating systems. However, the challenge in any recycling or reuse program is effective material recovery.

For wood, reclaimed or salvaged lumber is increasingly finding new life as beams, exposed trusses, millwork, flooring, finishes and furniture. According to a report from Dovetail Partners, more than 23 million tons of wood in the U.S. municipal waste stream and nearly 19 million tons in the construction and demolition stream have been recovered. However, the report estimates that 11.1 million tons and 17.3 million tons, respectively, are still wasted. Resources such as reusewood.org are available to provide builders and contractors with alternatives to disposal. Reclaimed wood has an added incentive—it continues to store carbon, while its use in place of new materials offsets net new greenhouse gas emissions.

A Natural Case for Wood in Construction

The United States has approximately 751 million acres of forested area—about one third of the country’s total land—and 56 percent is privately owned. Net forest growth has outpaced the amount of wood harvested for decades, supporting the idea that landowners who depend economically on the resource have a strong incentive for sustainable management. This aligns with global forest data, which indicates that forest products and industrial roundwood demands provide the revenue and policy incentives to support sustainable forest management.

Additionally, wood sequesters half its weight in carbon, and when used as a building material it secures that carbon for its full lifecycle. After trees are harvested, young saplings serve as a carbon sink, capturing additional CO₂ as they grow. As trees mature and decay, the sequestered carbon is released back into the atmosphere, zeroing out the environmental benefits that would have been preserved by building with wood. This means wood, across its full lifecycle, can play a significant role in enabling architects and engineers to reduce the environmental impact of modern buildings.

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