Katerra is a start-up construction company that has developed a vertically integrated cross-laminated timber (CLT) manufacturing supply chain and facility. Katerra commissioned the Carbon Leadership Forum (CLF) and the Center for International Trade in Forest Products (CINTRAFOR) at the University of Washington to perform a life cycle assessment (LCA) study to understand the environmental impacts and opportunities for impact reduction in Katerra’s CLT supply chain and manufacturing process. CINTRAFOR performed an LCA of the CLT supply chain and production process while the CLF performed a whole building LCA of a new building that used CLT produced at Katerra’s CLT facility.
We conducted a systematic literature search and meta-analysis of studies with side-by-side life cycle analysis comparisons of mid-rise buildings using mass timber and conventional, concrete and steel, building materials. Based on 18 comparisons across four continents, we found that substituting conventional building materials for mass timber reduces construction phase emissions by 69%, an average reduction of 216 kgCO2e/m2 of floor area. Studies included in our analysis were unanimous in showing emissions reductions when building with mass timber compared to conventional materials. Scaling-up low-carbon construction, assuming mass timber is substituted for conventional building materials in half of expected new urban construction, could provide as much as 9% of global emissions reduction needed to meet 2030 targets for keeping global warming below 1.5 °C. Realizing the climate mitigation potential of mass timber building could be accelerated by policy and private investment. Policy actions such as changing building codes, including mass timber in carbon offset crediting programs and setting building-sector-specific emissions reduction goals will remove barriers to and incentivize the adoption of mass timber. Private capital, as debt or equity investment, is poised to play a crucial role in financing mass timber building.
Life Cycle Assessment (LCA) has been used to understand the carbon and energy implications of manufacturing and using cross-laminated timber (CLT), an emerging and sustainable alternative to concrete and steel. However, previous LCAs of CLT are static analyses without considering the complex interactions between the CLT manufacturing and forest systems, which are dynamic and largely affected by the variations in forest management, CLT manufacturing, and end-of-life options. This study fills this gap by developing a dynamic life-cycle modeling framework for a cradle-to-grave CLT manufacturing system across 100 years in the Southeastern United States. The framework integrates process-based simulations of CLT manufacturing and forest growth as well as Monte Carlo simulation to address uncertainty. On 1-ha forest land basis, the net greenhouse gas (GHG) emissions ranges from -954 to -1445 metric tonne CO2 eq. for a high forest productivity scenario compared to -609 to -919 for a low forest productivity scenario. All scenarios showed significant GHG emissions from forest residues decay, demonstrating the strong need to consider forest management and their dynamic impacts in LCAs of CLT or other durable wood products (DWP). The results show that using mill residues for energy recovery has lower fossil-based GHG (59%–61% reduction) than selling residues for producing DWP, but increases the net GHG emissions due to the instantaneous release of biogenic carbon in residues. In addition, the results were converted to 1 m3 basis with a cradle-to-gate system boundary to be compared with literature. The results, 113–375 kg CO2 eq./m3 across all scenarios, were consistent with previous studies. Those findings highlight the needs of system-level management to maximize the potential benefits of CLT. This work is an attributional LCA, but the presented results lay a foundation for future consequential LCAs for specific CLT buildings or commercial forest management systems.
This series highlights five whole building life cycle assessments (WBLCAs) of buildings incorporating the building material known as cross-laminated timber (CLT) into some or all of their structure, using a primary cradle-to-grave system boundary. This case study series will serve as an educational resource for academics, professionals, and CLT project stakeholders. While there is some uncertainty about the best way to reduce greenhouse gas emissions from architecture and construction, using CLT and other wood building materials is one possible means to reduce the emissions associated with a building’s materials. When forests are managed sustainably, wood construction materials can contribute to climate change mitigation goals as an indefinite carbon store and as a replacement of other fossil-fuel intensive materials. WBLCA is an assessment method to estimate the environmental impacts of buildings; this series offers insight into the current possibilities and limitations of WBLCA for CLT buildings. The series begins with background information on WBLCA methods and CLT, a review of previously published CLT building WBLCAs, and a life cycle assessment of an individual CLT wall element using the WBLCA softwares Tally® and Athena Impact Estimator for Buildings (Athena IE).
Katerra has developed its own cross-laminated timber (CLT) manufacturing facility in Spokane Valley, Washington. This 25,100 m2 (270,000 ft2 ) factory is the largest CLT manufacturing facility in the world, and is capable of producing approximately 187,000 m3 of CLT per year. Katerra has also established a vertically integrated supply chain to provide the wood for the CLT factory. Production started in summer of 2019.
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 its CLT as well as the Catalyst Building in Spokane, Washington. The Catalyst is a 15,690 m2 (168,800 ft2), five-story office building that makes extensive use of CLT as a structural and design element. Jointly developed by Avista and McKinstry, Katerra largely designed and constructed the building, and used CLT produced by Katerra’s new factory. Performing a life cycle assessment (LCA) on Katerra’s CLT will allow Katerra to explore opportunities for environmental impact reduction along their supply chain and improve their CLT production efficiency. Performing an LCA on the Catalyst Building will enable Katerra to better understand life cycle environmental impacts of mass timber buildings and identify opportunities to optimize environmental performance of mid-rise CLT structures.
The goal, scope, methodology, and results of this analysis are detailed in this report.