Assessing the energy demand, carbon footprint and other environmental impacts from mass timber production: a critical review and meta-analysis

Abstract Mass timber products such as Cross-Laminated Timber (CLT) and Glued Laminated Timber (GLT) are increasingly positioned as low-carbon alternatives to concrete and steel in building construction. While widely cited for their carbon storage potential and reduced embodied emissions, their environmental performance assessment remains fragmented and geographically skewed. Existing environmental assessments disproportionately reflect European production conditions, limiting their relevance to other regions. This study addresses these gaps through a critical review and meta-analysis of 21 peer-reviewed and industry-based Life Cycle Assessments (LCA) and Environmental Product Declarations (EPD) of CLT and GLT production from North America, Oceania, and Japan, harmonized across key parameters such as system boundaries. Results show substantial regional variability in carbon emissions, with the median cradle-to-gate carbon emissions for CLT and GLT produced outside Europe being 52% higher (167 versus 110 kg CO 2 -eq/m 3 ), mainly due to differences in wood species, manufacturing practices, and energy sources. Cumulative energy demand (CED) varies widely, from 800 MJ m −3 to 9602 MJ m −3 , depending on the electricity grid carbon intensity. Product-level differences also emerge: GLT shows markedly higher acidification (+60%), smog formation (+84%), and ozone depletion (+99%), while CLT is associated with higher eutrophication (+71%), freshwater consumption (+20%), and non-hazardous waste generation (+67%). Despite comparable biogenic carbon uptake, regional and process-level factors significantly shape the sustainability profile of mass timber products. This study recommends region-specific LCA guidelines, improved reporting transparency, and regionally differentiated environmental impact benchmarks to support informed procurement and policy. The findings help guide material choices, regulations, and low-carbon strategies for sustainable construction.