Case Study on the Cradle-to-Gate Life Cycle Assessment of Softwood Lumber Production in New Brunswick, Canada

The construction sector increasingly emphasizes renewable materials like wood from sustainably managed forests due to wood’s low embodied carbon and carbon storage potential, contributing to climate change mitigation. This study applies life cycle assessment (LCA) to evaluate the environmental impact of softwood lumber manufacturing in New Brunswick, Canada. Data were gathered from a local softwood sawmill through survey questionnaires and on-site visits, capturing details on raw material extraction, production processes, and fuel sources used to power the sawmill. A life-cycle inventory (LCI) was developed using mass allocation for primary products and co-products such as chips and sawdust. The LCA software SimaPro, with the North American impact method TRACI 2.1, was employed to conduct the life cycle impact assessment (LCIA) and analyze emissions. Results indicated that kiln-dried sawed lumber’s greenhouse gas (GHG) emissions amounted to 43 kg CO2eq/m3. Manufacturing processes with various unit processes, particularly kiln-drying, contributed over 60% of emissions. Carbon storage in the final lumber product was calculated at 204 kg, translating to approximately 748 kg of CO2eq/m3, which was 12 times greater than its cradle-to-gate emissions. In this cradle-to-gate LCA, the stored biogenic carbon was counted as a potential credit. This value reflects only the upfront carbon balance and did not represent the entire life cycle, where end-of-life emissions could change this outcome. When used in long-life building constructions, the stored carbon could act as a temporary carbon sink.