Life-cycle assessment of solid hardwood flooring in the eastern United States

Abstract

This study conducted a cradle-to-grave life-cycle assessment (LCA) of solid hardwood flooring manufactured in the eastern United States. System boundaries in this study included the following information modules: raw material extraction (A1), raw material transportation (A2), product manufacturing (A3), product transportation (A4), installation (A5), product use (B1-B7), and end-of-life (C1-C4). Two disposal options were considered, landfilling and burning. The burning option captures heat, which displaces natural gas (D stage). A functional unit of 1 m² of flooring with a weighted average oven-dried mass of 12.06 kg/m² of flooring (for 75 years of estimated service life of the building) was used to present the LCA results. Primary data were collected along the supply chain including resource procurement, manufacturing, and logistics using surveys. Data not available from the surveys, especially regarding use and disposal of the wood flooring, were supplemented from literature and industry experts. This LCA study followed the guidelines of the International Organization for Standardization standards and product category rules (PCR), Underwriters Laboratories-Environment Part A (Building-Related Products and Services) PCR and Part B (Flooring EPD Requirements) PCR. Life-cycle impact assessments (LCIA) were estimated using the tool for the reduction and assessment of chemical and other environmental impacts (TRACI), CML baseline, and cumulative energy demand. Among all segments of the life cycle (cradle-to-grave), the manufacturing module (37%) and use stage (57%) were the most substantial contributors to the total cradle-to-grave environmental impacts of solid hardwood flooring. The cradle-to-grave LCIA results showed that 26.65 kg CO₂eq were released during the life cycle of 1 m² of solid hardwood flooring. Considering biogenic carbon emissions, the net global warming potential impact was decreased to 12.27 kg CO₂eq as a result of carbon being stored in the landfill (82% of total waste disposed of in landfill). Each square meter of solid hardwood flooring consumed 610.5 MJ of energy, and about 20.3% of the total primary energy used came from renewables, especially biomass. This study showed that solid hardwood flooring has a low carbon footprint. It stored carbon (14.37 kg CO₂eq/m² flooring) for the long-term, which can help mitigate climate change.

Citation

Heidari, M. Davoud; Bergman, Richard D.; Salazar, James; Hubbard, Steven S.; Bowe, Scott A. 2023. Life-cycle assessment of solid hardwood flooring in the eastern United States. Research Paper FPL-RP-717. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 43 p. https://doi.org/10.2737/FPL-RP-717.