Browsing by Author "Stenson, Jason"

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    Carbon Narratives for Design Planning
    (Institute for Health in the Built Environment, University of Oregon, 2023) Bloom, Ethan; Chidambaranath, Pallavl; Fretz, Mark; Kwok, Alison; Mahic, Alen; Martin, Katherine; Northcutt, Dale; Rowell, Joshua; Stenson, Jason; Van Den Wymelenberg, Kevin; Onell, Elaine; Puettmann, Maureen
    The carbon story for buildings exemplifies the complexity and interconnection of embodied and operational carbon contributing to global greenhouse gas (GHG) emissions causing climate change. A myriad of considerations are in play, from natural resource management, extraction, processing, transportation, construction, operation and ultimately end of life, for every material and every building. Buildings currently represent about 37% of annual global CO2 emissions.1 About 10 GtCO2 annually come from building operations, which is at an all-time high, and about 3.6 GtCO2 from producing major materials used in building construction.1 As the world economy grows and living standards rise, the global consumption of raw materials is expected to nearly double by 2060.1 Decarbonizing the building sector will require coordinated action from numerous and diverse stakeholders in areas such as science, policy, and finance. Architects, engineers, and construction (AEC) professionals can take greater responsibility through building material selection, but this important decision-making process requires having the right data at hand when it’s needed. We believe the quickest means to reducing global warming potential through building material selection in the near term is to: 1) use and reuse materials efficiently, including existing structures; 2) use low embodied-carbon material options in place of materials that are derived from carbon intensive production; 3) employ bio-based materials, such as timber, that are renewable and remove carbon from the atmosphere during their growth, then design for durability and longevity, disassembly, and end-of-life reuse to ensure that the stored carbon remains out of the atmosphere for as long as possible; 4) create opportunities to use mill and production waste in products with long lifespans. At present, timber is typically less carbon intensive than steel or concrete if sourced from forests with sustainable forest management practices. On a longer time horizon, we believe: 1) significant reductions in all industry emissions and continued improvements in sequestration are imperative for all building materials including wood, concrete and steel; 2) transitioning a significant percentage of our buildings and cities to timber structures could significantly reduce carbon emissions in time, but only if sustainable forest management practices are used in concert with strong forward-thinking governance and broad-reach planning efforts; 3) sustainable forestry practices, along with the life cycle assessment methodologies and design tools used to quantify their impacts, are still in a period of development and refinement, and should be expected to be a moving target in the foreseeable future with advancement in our collective understanding and through greater adoption of these systems and practices. This guide, Carbon Narratives for Design Planning, was developed to acknowledge areas of influence when considering selection of mass timber as a primary building material. It is a complicated narrative, but one that designers and their clients are embracing based on multiple positive attributes of mass timber. At the same time, there is consensus that more transparency and uniformity in the embodied carbon story of wood products from forest to building site will lead to more informed decisions and improved environmental outcomes when specifying materials during design planning. This project offers a synthesis of available information for primary materials of structural building systems, with particular focus given to mass timber. We highlight ways in which mass timber can reduce whole building embodied carbon yet recognize that the narratives become complicated when comparing carbon content in mass timber structural systems against concrete or steel. The narrative becomes further nuanced when forest management practices, biogenic carbon and unknown material end-of-life pathways become part of the equation. The guide is structured in five parts, describing: 1) carbon in the built environment; 2) carbon, climate and forests; 3) carbon and mass timber; 4) carbon and concrete and 5) carbon and steel. Additional resources included in the appendices are survey results from 180 AEC practitioners from across North America, many with international project experience, that were used to structure a series of five workshops that took place between April and September 2021: 1) Wood Certifications: What is the difference and is it worth the extra cost? 2) Beyond the EPD: What aren’t we considering? 3) Comparing Carbon Narratives: How do concrete, steel and mass timber actually perform? 4) LCA Assumptions: Counting carbon neutrality versus climate neutrality? 5) Design for Building End of Life: Assumptions versus Actualities. Workshops drew on expertise and perspectives from individuals in forest ownership and production at small and large scales, manufacturers, non-profits, government and academia. Due to the Covid-19 pandemic, these workshops were held entirely virtual, which allowed participation of national and international experts. Links to workshop recordings are hosted on the Institute for Health in the Built Environment (IHBE) and NetZed Laboratory websites. The immediate goal of this work is to create a common narrative for use by AEC professionals in their current and future work involving specification of building materials and associated carbon impact from those choices. Longer range goals of this work are based on the belief that these carbon narratives are key to advancing research, innovation, and cross-disciplinary urgency surrounding broad efforts to decarbonize the building sector and the materials used in the built environment.
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    Evaluating Volatile Organic Compound Emissions from Cross-Laminated Timber Bonded with a Soy-Based Adhesive
    (MDPI, 2020-10) Yauk, Michael; Stenson, Jason; Donor, Micah; Van Den Wymelenberg, Kevin
    Volatile organic compound (VOC) emissions from indoor sources are large determinants of the indoor air quality (IAQ) and occupant health. Cross-laminated timber (CLT) is a panelized engineered wood product often left exposed as an interior surface finish. As a certified structural building product, CLT is currently exempt from meeting VOC emission limits for composite wood products and confirming emissions through California Department of Public Health (CDPH) Standard Method testing. In this study, small chamber testing was conducted to evaluate VOC emissions from three laboratory-produced CLT samples: One bonded with a new soy-based cold-set adhesive; a second bonded with a commercially available polyurethane (PUR) adhesive; and the third assembled without adhesive using dowels. A fourth commercially-produced eight-month-old sample bonded with melamine formaldehyde (MF) adhesive was also tested. All four samples were produced with Douglas-fir. The test results for the three laboratory-produced samples demonstrated VOC emissions compliance with the reference standard. The commercially-produced and aged CLT sample bonded with MF adhesive did not meet the acceptance criterion for formaldehyde of ≤9.0 μg/m3. The estimated indoor air concentration of formaldehyde in an office with the MF sample was 54.4 μg/m3; the results for the soy, PUR, and dowel samples were all at or below 2.5 μg/m3.
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    Mass Timber Panelized Workforce Housing in Oregon, U.S.
    (Institute for Health in the Built Environment, University of Oregon, 2023) Sheine, Judith; Fretz, Mark; O'Halloran, Simone; Gershfeld, Mikhail; Stenson, Jason
    Mass timber panel production came to the United States after developments in Europe and Canada; the first domestic structural cross-laminated timber (CLT) panels were manufactured by DR Johnson Wood Innovations in Riddle, Oregon in 2015. With its history of timber product manufacture, the state has embraced this new material for its potential for economic development in the U.S. As in many places in the U.S., Oregon has a critical shortage of affordable housing and it has been challenging to find paths for mass timber to enter this market where light-wood-frame construction is dominant. In 2018, Freres Engineered Wood, working with the TallWood Design Institute, a collaboration between the University of Oregon and Oregon State University, developed a new product: mass plywood panels (MPP). This product provides a possibility for constructing single-family houses economically with mass timber using thin panels derived from small diameter logs. This paper describes the research leading to a pilot project utilizing MPP for workforce housing in Milwaukie, Oregon.