Life cycle assessment of wood plastic decking manufacturing: Reduction of environmental impacts based on an industrial case study in China

Climate change has spurred global efforts to mitigate carbon emissions, presenting significant challenges for the manufacturing sector in reducing the ecological footprint of its products. This study investigates a cradle-to-grave life cycle assessment (LCA) of wood–plastic decking, focusing on a Chinese facility with an annual production capacity exceeding 20,000 tons. The results indicate that raw material acquisition and key manufacturing processes—raw material premixing, pelletizing and co-extrusion are the primary contributors to environmental impacts. Transitioning from conventional energy sources (e.g., China's electricity grid) to solar energy could reduce global warming potential (GWP) by 38.9 %. While mechanical testing confirms the viability of recycled wood plastic composites (WPCs) for partial raw material substitution, its rheological properties limit broader reuse. The recycling process, though energy-intensive due to its high energy consumption during milling, the GWP remains 84.2 % lower than incineration. Sensitivity analysis revealed that varying recycling rates from 25 % to 100 % significantly reduced marine eutrophication potential, freshwater ecotoxicity potential, marine ecotoxicity potential, and human non-carcinogenic toxicity potential by up to 8 %, while long-distance maritime transportation (up to 20,000 km) increased impacts like ozone depletion and human health ozone formation potentials. In addition, the substitution rate of RP had a relatively large effect on environmental impacts, whereas the service life showed minimal influence. This study offers actionable insights for stakeholders in the wood-plastic decking industry to reduce their environmental impact without requiring substantial modifications to existing production processes.