Environmental life-cycle assessment of preservative treated southern yellow pine lumber with borate wood preservative.

摘要

Due to public pressure, strict environmental regulations, and customer demands, companies are becoming more concerned with the environmental impacts of their operations. Pressures are growing to reduce harvesting or even quit all forestry operations, thereby ignoring that manufacturing of alternative materials to wood may cause environmental impacts equal to or greater than the production of wood products. In addition, growing concerns over the mammalian toxicity of conventional wood preservatives provide an incentive to look for alternative treatments. Tim-bore wood preservative, a boron-based preservative, poses no known significant risk to humans or animals, but has been found to be resistant to most economically important wood destroying organisms in other countries.; This study encompasses production of Tim-bor-treated southern pine lumber from extraction through pressure treatment (cradle-to-gate) using the LCA method. The study is confined to extraction of boron from the earth, processing of Tim-bor, transportation of the Tim-bor preservative, timber harvesting, manufacturing and transportation of southern pine lumber, and the pressure treatment of southern pine lumber with the Tim-bor wood preservative.; The study examined five subsystems: (1) Boron Operations, (2) Tim-bor Production, (3) Timber Harvesting, (4) Lumber Production, and (5) Wood Treating. Kiln drying of lumber in the Lumber Production and Wood treating subsystems accounted for most of the energy requirement for the entire system. The Wood Treating subsystem alone consumed 93 percent of the total electricity used in the system. The LCI results clearly reflect the low significance in the production of the Tim-bor wood preservative to the overall product. Comparisons of the environmental profile for Tim-bor-treated lumber with alternative building materials indicate that an interior wall framing from Tim-bor treated lumber consumes nearly 59% less energy than reported for a wall framed out of steel. Life cycle impact assessment results indicate that the type of fuel source used has a significant effect on impacts such as climate change indicators (CO₂) contributing to global warming. Because lumber drying operations used most of the energy, modifying these operations has the greatest potential for reducing environmental impacts of the production of Tim-bor treated lumber.