While high-rise mass-timber construction is booming worldwide as a more sustainable alternative to mainstream cement and steel, in South America, there are still many gaps to overcome regarding sourcing, design, and environmental performance. The aim of this study was to assess the carbon emission footprint of using mass-timber products to build a mid-rise low-energy residential building in central Chile (CCL). The design presented at a solar decathlon contest in Santiago was assessed through lifecycle analysis (LCA) and compared to an equivalent mainstream concrete building. Greenhouse gas emissions, expressed as global warming potential (GWP), from cradle-to-usage over a 50-year life span, were lower for the timber design, with 131 kg CO2 eq/m2 of floor area (compared to 353 kg CO2 eq/m2) and a biogenic carbon storage of 447 tons of CO2 eq/m2 based on sustainable forestry practices. From cradle-to-construction, the embodied emissions of the masstimber building were 42% lower (101 kg CO2 eq/m2) than those of the equivalent concrete building (167 kg CO2 eq/m2). The embodied energy of the mass-timber building was 37% higher than that of its equivalent concrete building and its envelope design helped reduce space-conditioning emissions by as much as 83%, from 187 kg CO2 eq/m2 as estimated for the equivalent concrete building to 31 kg CO2 eq/m2 50-yr. Overall, provided that further efforts are made to address residual energy end-uses and end-of-life waste management options, the use of mass-timber products offers a promising potential in CCL for delivering zero carbon residential multistory buildings.
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Acknowledgments: This article is part of a larger five-phase project initiated by the Nature Conservancy (nature.org) through generous support from the Climate and Land Use Alliance and the Doris Duke Charitable Foundation (DDCF). The work upon which this project is based was also funded in whole or in part through a cooperative agreement with the USDA Forest Service, Forest Products Laboratory, Forest Products Marketing Unit (17-CA-11111169-031). * The Nature Conservancy initiated this project to further the collective understanding of the potential benefits and risks of increasing demand for forest products. The Conservancy focuses on delivering critical safeguard frameworks to mitigate potential risks to forest ecosystems as mass timber demand increases. * In accordance with Federal Law and U.S. Department of Agriculture policy, this institution is prohibited from discriminating on the basis of race, color, national origin, sex, age, or disability. (Not all prohibited bases apply to all programs.) To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, Room 326-W, Whitten Building, 1400 Independence Avenue, SW, Washington, DC 20250-9410 or call (202) 720-5964 (voice and TDD). USDA is an equal opportunity provider, employer, and lender.
Funding: This research was funded by USDA Forest Service, Southern Region, Wood Innovations Program (19-DG-11083150-023).
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- Carbon storage
- Mid-rise timber buildings
- Passive zero carbon housing