Environmental Assessment of the Production and End-of-Life of Cross-Laminated Timber in Western Washington

Abstract

Cross-laminated timber (CLT) is a large-scale engineered wood product that may be used as structural components in buildings. Increase in city population leads to higher demand for tall buildings. CLT has the potential of becoming an important alternative material to concrete in an uprising construction industry. The State of Washington is becoming a leader in adopting CLT in the U.S., but research and data at the regional level are lacking, and few studies have considered the impacts of the treatment of CLT at the end of a building’s service life. This research developed an environmental assessment to investigate the environmental impacts of CLT over the course of resources extraction, manufacturing, transportation, and end-of-life (EoL) using life cycle assessment (LCA). The role of facility location and wood species mix involved in the life cycle of CLT are considered. This research also investigated the role of CLT as a construction material in reducing C&D waste in Washington. EoL scenarios are developed based on current waste treatment scenarios in Washington. Important results from this research included: (a) carefully selecting the facilities and wood species can significantly reduce the environmental impacts of CLT production, (b) applying CLT to partially replace concrete and steel in buildings can reduce waste generation associated with C&D, and (c) the environmental impacts associated with CLT at the EoL stage may be significantly reduced when landfill disposal is avoided and that CLT panels are reused. This research contributes references and new knowledge associated with CLT to the construction industry, forestry industry, policy-makers, as well as the academic community, and helps to build a more resilient forest industry.