The Carbon Leadership Forum finds mass timber nearly offsets all upfront embodied carbon in the Catalyst Building
By: Craig Curtis and Hans-Erik Blomgren
As a vertically integrated company, Katerra controls the entire end-to-end building process. This offers us insight into the full building lifecycle and an unparalleled opportunity to address long-standing environmental inefficiencies in building product sourcing, manufacturing, construction, and operation. Katerra’s investment in cross-laminated timber (CLT) — which we believe will become the backbone for future generations of high-performance, low-carbon buildings — is a core strategy for lowering the environmental footprint of the built environment we are creating.
To celebrate an important milestone, we are proud to release a Life-Cycle Analysis (LCA) of our CLT manufacturing process and Catalyst – our first turnkey mass timber project and the first building to feature CLT produced in Katerra’s Spokane Valley CLT factory. Katerra commissioned the Carbon Leadership Forum (CLF) and Center for International Trade in Forest Products (CINTRAFOR) at the University of Washington to analyze the environmental impacts of our CLT as well as the Catalyst building in Spokane, Washington. These two organizations are the preeminent leaders in their respective fields; CLF recently released an embodied carbon calculator for the construction industry and CINTRAFOR is well known for its research to support sustainable forestry and forest products trade.
Our goal in pursuing this analysis was twofold: To better identify opportunities to reduce environmental impacts in our supply chain and improve CLT production efficiencies, and to examine the life cycle environmental impacts of mass timber at the whole building scale and identify opportunities to optimize the environmental performance of mid-rise mass timber structures.
Before diving into the LCA results, here is a brief overview of our CLT factory and the Catalyst project:
The Carbon Leadership Forum
The Carbon Leadership Forum at the University of Washington is a global leader in accelerating transformation of the building sector to radically reduce and ultimately eliminate the embodied carbon in building materials and construction. Under the leadership of Kate Simonen, AIA, SE, the Carbon Leadership Forum is pioneering research, creating resources, and incubating member-led initiatives to achieve net-zero embodied carbon in buildings
Katerra’s Spokane CLT Factory
Katerra’s Spokane Valley factory is our first mass timber production line, occupying 29 acres in eastern Washington state. The 270,000 square foot facility features one of the largest CLT presses currently in operation globally and is sited near rail lines and interstate highways for ease of transport. As part of our sustainability commitment, all lamstock for Katerra’s CLT is currently sourced from well-managed forests and is, at a minimum, certified PEFC (Programme for the Endorsement of Forest Certification) or SFI (Sustainable Forestry Initiative).
At 159,000 square feet, the Catalyst building aims to be one of the largest zero energy and zero carbon buildings in North America, and will pursue Zero Energy Certification by the International Living Future Institute. The five-story office building is a result of a cross-industry team of partners, including utility provider Avista, construction engineering firm McKinstry and Katerra. Working with Katerra Design Partner Michael Green Architecture as the design architect, Katerra is the Architect of Record and General Contractor for the building, which also features CLT manufactured in our factory. The building makes extensive use of CLT as a structural and design element, including the floors, shear walls, and building envelope which enables near-Passive House levels of thermal performance.
“What’s really unique about this LCA is Katerra’s vertical integration. It offered us the ability to assess impact at the manufacturing and building scale and integrate it into one analysis. This study arms Katerra with important data to make informed decisions to reduce carbon as they build more mass timber buildings in the future.”Kate Simonen, AIA, SE and founding director of the Carbon Leadership Forum
LCA Study Results
CLF’s and CINTRAFOR’s research determined that when our factory is at production capacity the embodied carbon impact of Katerra’s CLT will be between 130 – 158 kg CO2e/m3 which falls at the lower end of the spectrum of the results from other LCA studies of CLT produced in the United States. In other words, our high-volume factory will produce CLT with a smaller environmental footprint compared to other manufacturers.
The life cycle assessment of the Catalyst’s building structure and envelope estimated the upfront embodied carbon of the building to be only 207 kg CO2e/m2. Considering the Catalyst building stores approximately 204 kg CO2/ m2 of biogenic carbon, the CLT and glulam elements nearly offset its upfront embodied carbon. While the study did not make a direct comparison of the Catalyst to similarly sized buildings constructed of steel or concrete, its upfront embodied carbon impact is significantly lower than that of other North American commercial office buildings in the Embodied Carbon Benchmark Study.
To better assess the materials responsible for the highest global warming potential (GWP) within the Catalyst building, the material groups were ranked according to GWP impact, mass and volume. The left-most chart in the below figure shows that wood and concrete have the highest GWP impacts and that their contributions are nearly equal. This is because the carbon stored in the mass timber is accounted for separately and is not reflected in this chart. In comparison, the center and right-most charts show that concrete has a significantly higher overall mass than wood but a lower overall volume on this project. This chart demonstrates that GWP impacts of materials in a building are not necessarily correlated with mass or volume. If the primary structural elements of the building were made of concrete instead of mass timber, the overall GWP of the building would likely be significantly higher.
“We’re applying the results of this study in real time as we develop our mass timber building platforms. The analysis is guiding our selection of lower-carbon materials that are available at scale. Ultimately, this LCA will yield a positive impact over many buildings, and we hope through publication of this report, it influences others to realize the environmental benefit of this new way of designing and building.”Craig Curtis, FAIA and chief architect for Katerra
For more insights, we encourage you to read the LCA Executive Summary and the full LCA Report. This in-depth analysis includes substantive details about the embodied carbon in our CLT and the Catalyst building as well as recommendations for steps we can take to further reduce the environmental impact of our CLT supply chain and mass timber building design.
Mass timber has captured the imagination of architects, environmentalists and building occupants alike. With the building sector responsible for nearly 40 percent of annual global carbon emissions, and cement alone representing 8 percent of the world’s emissions, mass timber has the potential to play an integral role in reducing the environmental footprint of buildings. Studies like the Katerra CLT and Catalyst LCA report are essential to understanding mass timber’s impact and quantifying potential benefits as we collectively work to meet broader sustainability goals.
We look forward to applying these learnings as we partner with our customers to improve environmental performance across the end-to-end building process.