Steel or Wood Frame? A Life Cycle Comparison of External Wall Systems through Deconstruction and Reuse

The Construction sector uses 40% of the earth's resources, much of which ends up as "wastes" from our civilization. We can reduce resource use and eliminate demolition waste by simply reusing building materials. Some building components are easy to take apart and reuse while others require additional costs and effort. Some generate more environmental impacts during their recycling. The paper presents a study on understanding the lifecycle impact of recycling different building components and materials, thus allowing the industry to better understand the true lifecycle environmental impacts of reuse and recycling. The study compares the embodied energy, global warming potential, and water use of a wood frame and a steel frame for a manufactured home in the United States. The analysis assumes the wood frame would be demolished and rebuilt for three life cycles, while the steel frame was assumed to be continuously reused. The analysis is based on process-based life cycle analysis (LCA) and hybrid-LCA. Considerations on transportation distances and reuse rates were made. The analyses showed that, by using a cradle-to-cradle (C2C) framework, both methods generate conflicting results. The impact of the results to manufacturers, designers, policy-makers, building owners, and researchers are discussed.