The Kendeda Building for Innovative Sustainable Design / The Miller Hull Partnership in collaboration with Lord Aeck Sargent / Photo Jonathan Hillyer
Wood has many attributes that make it well suited to sustainable design. Wood products have low embodied carbon compared to other building materials, which indicates fewer greenhouse gas emissions, and they continue to store carbon absorbed by the trees while they were growing. Low embodied carbon + stored carbon = lower carbon impact. Wood is also natural and renewable. It can contribute to energy efficiency and biophilic design, and is durable, adaptable and re-useable. Explore the sections below for resources that can help you make informed sustainability decisions.
Use these Resources to Inform Your Building Material Choices
Practical guidance on whole building life cycle assessment, biogenic carbon, carbon storage, environmental product declarations, and more.
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Introduction to Whole Building Life Cycle Assessment: The Basics
Life cycle assessment (LCA) is used to quantify environmental impacts over the lifetime of a product or system, from initial extraction of raw materials through manufacture, distribution, use, and final disposal.
Less Embodied Carbon + Stored Carbon = Lower Carbon Impact
How do we build sustainably and achieve carbon-reduction goals while also meeting the housing and infrastructure needs of a growing population? One answer is more wood buildings.
According to Architecture 2030, buildings are responsible for nearly 40% of global greenhouse gas (GHG) emissions. Embodied carbon—i.e., GHGs associated with materials and construction processes throughout the lifetime of a structure—accounts for about 11%, and most of this (9%) is related to the use of concrete, iron and steel.1 Embodied carbon, especially upfront emissions associated with manufacturing materials and constructing the building, can be significant. The upfront energy associated with a traditional non-wood building is roughly equal to the energy required to operate that same building for 17 years!2
Wood products have low embodied carbon
Manufacturing wood products requires less fossil fuel-based energy than either steel or concrete; most of the energy comes from renewable biomass (e.g., bark and other residual fiber) that would otherwise go to waste.3 Substituting wood for fossil fuel-intensive materials reduces embodied carbon and is an important step in reaching our near-term climate goals.
Wood buildings store carbon
As trees grow, they absorb carbon dioxide (CO2) from the atmosphere, release the oxygen (O2), and incorporate the carbon into their wood, leaves or needles, and roots. This carbon is referred to as biogenic carbon. When trees are manufactured into building materials, the wood continues to store carbon. (Wood is 50% carbon by dry weight.4) By using wood in buildings, we keep this carbon out of the atmosphere for the lifetime of the structure—longer if the wood is reclaimed and reused or recycled.
“Every year, 17,000 buildings constructed with other materials could be built with wood. In most cases, it costs about the same to build with wood, and yet the environmental benefits are significant. Building with innovative wood products from sustainable, properly managed forests is a relatively easy way to alleviate a sizable amount of U.S. carbon emissions.”
– Jennifer Cover, President and CEO, WoodWorks, Testimony to the Committee on Energy and Natural Resources, United States Senate
Forests and cities work together to keep carbon out of the atmosphere
Sustainable forest management practices such as those used in North America are essential to the forest-carbon cycle. While wood buildings lock carbon into the built environment, the next generation of trees begins to grow and absorb CO2. This helps to ensure that our forests remain a carbon sink while creating a sustainable supply of wood for new buildings.
Strong markets for wood products incentivize sustainable forest management by providing an economic reason to keep forest land forested instead of converting them for other uses. They also encourage landowners to invest not only in forest regeneration, but thinning and other landscape restoration efforts that promote forest health and reduce the risk of wildfire.
Learn to Account for Biogenic Carbon in Your Projects
This series of WoodWorks articles is intended to help developers and design teams account for biogenic carbon in their wood building projects. It includes an overview followed by articles that examine accounting practices at each stage of a project’s life cycle, the nuances of different life cycle assessment tools, long-term carbon storage and delayed emissions, and recommendations for reporting biogenic carbon in a way that aligns with international standards.
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Have you tried the WoodWorks Carbon Calculator?
Input the volume of structural wood in your building and this tool will estimate its carbon impact—including carbon stored in the wood and avoided greenhouse gas emissions—and how long it takes U.S. and Canadian forests to grow that volume of wood. While it doesn’t offer the thoroughness of an LCA, the calculator can help quantify the benefits of a wood structure for your team, client or community.
Crescent Real Estate has found that sustainable architecture, including buildings with a lower carbon impact, appeals to a wide range of tenants. Working with OZ Architecture, KL&A Engineers & Builders, and Adolfson & Peterson Construction, Crescent made sustainability a priority for Platte Fifteen, a five-story CLT office building in Denver. In addition to a technical case study on its design and construction, this project also has an in-depth life cycle assessment (LCA) report.
Biophilic design is increasingly used to boost occupant well-being by creating a connection to nature through the use of natural elements like daylight, plants, water and exposed wood. These elements have been attributed to positive outcomes in humans—from reducing stress to boosting productivity.
In terms of operating energy, wood has the advantage of low thermal conductivity compared to steel and concrete.5 As a result, wood buildings are easy to insulate to high standards.
While any structural system can be designed to achieve a tight building envelope, the precise manufacturing of mass timber systems can provide exceptional air tightness. Wood is also proving to be a good choice for designers who want to meet the Passive House (Passivhaus) standard or create net-zero operational energy buildings. Read about 11 E Lenox in Boston, a seven-story mass timber Passive House project from design-build firm Haycon and Monte French Design Studio.
Because many factors have a greater influence on energy efficiency than the choice of structural material, a more relevant point for many building designers is that wood building systems have low embodied carbon. LCA studies consistently show that wood outperforms other materials in this area.6,7
