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CEE Class 226

Life Cycle Assessment for Complex Systems

 Life cycle assessment, as a part of the wider field of Industrial Ecology, is the systematic analysis of global, regional and local material and energy flows and uses that are associated with products, processes, industrial sectors, and economies. Energy consumption, non-renewable and renewable materials consumption, air pollutant emissions, waterborne pollutant effluents and solid waste generation associated with human activities are tracked. These analyses are the foundation of industrial ecology, which seeks to design and manage products and services that meet human needs in a sustainable manner.

This course is designed as an interdisciplinary course. Industrial designers, engineers, natural resource managers and policy makers, business managers, environmental health professionals, regulators, and consumers each play a critical role in shaping the environmental profile of the various infrastructure, building, and product systems that support us. A framework is presented for analyzing multi-stakeholder interests and the consequences of their decisions and actions. Ecological, economic, social, political, and technological factors that influence the life cycle of these systems will be considered. This life cycle encompasses raw materials acquisition and processing, manufacturing, use, resource recovery, and the ultimate disposal and fate of residuals.

The course will provide you with analytical tools and methods for implementing principles of life cycle analysis and industrial ecology. The practical applications covered in the course will be based largely on current research in the area of life cycle assessment (LCA), life cycle design, and life cycle optimization. Life cycle assessment is a comprehensive tool for identifying and evaluating the full environmental burdens associated with a system from production through retirement. This methodology is used for comparative analyses of alternatives including building materials (biobased vs petroleum based), energy systems (renewable and fossil fuels), consumer products and packaging, and building or infrastructure construction methods. Other analytical tools covered include ecological footprint analysis, carbon footprint analysis (life cycle assessment of greenhouse gases), life cycle cost analysis, and other metrics such as ecosystem service assessment and single score sustainability indicators. Life cycle design focuses on integrating environmental considerations into product and process design. The challenge is to align and meet performance, cost, legal, and cultural requirements while achieving environmental and social impact improvements. Life cycle optimization combines life cycle design with computational algorithms for iteratively designing or managing a system for optimal life cycle performance.

The current syllabus for this class can be found at syllabus.stanford.edu (enter subject as "CEE" to view all CEE syllabi)

 

Student Projects

Xerxes FRP Tank LCA: FRP versus CIP Tanks

Xerxes, a producer of commercial-scale petroleum storage tanks, has developed an FRP storage tank as an alternative to cast in place (CIP) concrete tanks for water storage. The group did an LCA to compare the relative impacts of both tanks (using a 60,000-gallon functional unit to compare). Within the largest environmental impact category — heavy metals — the Xerxes FRP tank performed better; the FRP tank was found to have a lower overall environmental impact score. The team performed a sensitivity analysis, finding that the resin content of the FRP tank was the primary factor in the product’s environmental impacts. The authors’ final recommendation to Xerxes was to investigate the possibility of recycling their FRP tanks at the end of life — reusing recycled tank material in the manufacturing process would significantly improve environmental impacts and provide potential for LEED credits.

Comparative Life Cycle Assessment of Traditional Concrete and Concrete Made with Fly Ash

Christa Heavey, Angelica Hernandez, Shea Hughes, Lindsay Willman

The team conducted an LCA for Headwaters Resources to examine the environmental impacts associated with concrete pavement made with fly ash (a natural byproduct of coal combustion) as a partial replacement of Portland cement (the cement manufacturing industry is one of the largest emitters of carbon dioxide in the U.S.). The group used a functional unit of a one-mile stretch of highway pavement in Palo Alto for a life of 50 years. The fly ash mixture resulted in lower environmental impacts across all environmental indicators, including the area of main concern — Global Warming Potential.

A financial and economic analysis indicated that concrete with fly ash was also less expensive over the full life cycle of the product; this is most likely due to increased strength and durability and lower initial cost of fly ash mixtures. The authors recommend that further benefits could be realized from minimizing the transportation distance of fly ash and in further increasing the amount of fly ash in concrete mixtures.

Comparative Life Cycle Assessment of Agricultural Produce Systems: Urban vs. Greenhouse Farming

Hunter Ploch, Matt Hepworth, Ben Laboy, Sean Wallace, Sean Morris

The group compared the life cycle costs of producing 1 kiloram of tomatoes using Green City Growers 4-by-8-foot raised bed vegetable gardens with the costs of producing the same amount of tomatoes using a traditional greenhouse garden. The Green City Growers beds proved to have lower environmental impacts across almost every indicator category, mostly due to decreased transportation distances when compared to large agriculture and avoided heating for greenhouse growing methods. However, the tomato grown in the planter system was found to have a much higher life cycle cost. The group found that costs were reduced when more planters were added to the system, reducing maintenance costs; nine planters were required to make Green City Grower’s product cost-comparable to its comparator.

Hampton Creek ™ Foods Beyond Eggs™ Egg Replacer: LCA

Hunter Ploch, Matt Hepworth, Ben Laboy, Sean Wallace, Sean Morris

The group conducted an LCA to compare the environmental impacts of commercial mayonnaise to Just Mayo™, an animal-product-free mayonnaise made using Hampton Creek Foods (HCF)’s egg replacer. The study used a functional unit of 1 metric ton of mayonnaise distributed in jars to a Whole Foods store in San Francisco. The group found that commercial mayonnaise production was associated with significantly higher GHG emissions; HCF’s product had, in fact, negative environmental cost, mostly due to carbon sequestration and crop residue reuse from rapeseed crops.

Life Cycle Assessment on Recycling of Used Motor Oil

Hao Liu, Shunichi Matsuda, Bingrong Ng, Kunal Singh

An LCA was conducted to compare motor oil production by conventional means (through refinement of crude oil) with re-refining of used motor oil. The group used a functional unit of 1,000 gallons of motor oil produced with each method and found that the crude oil refinery process was preferable to the recycling process both in terms of cost and environmental impact. Impacts and costs for the recycling process were shown to be largely driven by transportation — reducing these transportation distances by a factor by at least half would be necessary for the recycling process to equal traditional refining. The authors suggest that strategically locating oil-recycling facilities near sources of used motor oil could potentially reduce the environmental impact of the recycling process to well below that of the crude oil refining process.

SFO: LCA of Standard vs. Dynamic Glass Windows

Emily Paris, Chandrika Srivastava, Brock Petersen, Taylor Vencill, Ryan Satterlee

An LCA was conducted to compare costs and environmental impacts of standard glass windows with dynamic glass windows (which change tint and thus solar heat transmittance to reduce energy consumption and are being considered for a net-zero building at SFO). The comparison was done through the functional unit of SFO’s Airfield Operations building (many design elements would change based on the type of window selected, such as lighting and HVAC). Using an eQuest model in addition to SimaPro, the group found that dynamic glass windows would result in lower lifetime impacts for energy use, GHG emissions and almost all criteria pollutants, while lowering user and environmental costs.

Life Cycle Assessment of Fiber Reinforced Polymer (FRP) and Aluminum-Framed Glass Curtain Wall (AGCW) Façade Panels

Victoria Brumbaugh, Amy Egerter, Skyler Holloway, Grace Stephens, Allison Littman

The group conducted a life cycle inventory, impact assessment and costing of Kreysler & Associates’ design for Fiber Reinforced Polymer (FRP) panels compared with Enclos’ design for Aluminum-Framed Glass Curtain Wall (AGCW) panels, as considered for use in the SFMOMA expansion over a 25-year service life. The life cycle costs of the FRP panels were found to be lower than the AGCW system. An analysis of environmental impacts indicate that the use phase of the façade system was the main life cycle performance driver — overall the AGCW façade system outperformed the FRP façade system. However, because the disparity was minimal, the authors recommended that life cycle costs drive the decision to use FRP panels within the SFMOMA design.

Life Cycle Assessment of Stahlin’s Composite Enclosures

Anthony Alvarado, Luis Cruz, Angela Kwok, Kristhian T. Morales, Laurelann Trinidad

An LCA of three industrial enclosures was conducted to compare the environmental impact of a fiberglass-reinforced composite unit produced by Stahlin Enclosures to comparable painted carbon steel and stainless steel enclosures produced by a competitor. By analyzing a functional unit of a high-impact resistant environmental protection for electrical equipment through a 25-year service life, the composite enclosure and painted carbon steel enclosure were found to have similar environmental impacts. The painted carbon steel option, however, was found to be the least energy- and GHG-intensive with lower short-term ecological and human health impacts. The authors conclude that while the calculated life cycle costs for the Stahlin enclosures were less than competitor costs, environmental impacts are still cause for concern.

Kreysler Fiber Reinforced Polymer Panels Comparison

Amelia Celoza, Gretchen Heberling, Christine Jun, Anthony Kinslow, Philip Pan

The group performed an LCA to compare the carbon dioxide emissions of Kreysler& Associates’ fiber reinforced polymer (FRP) exterior building cladding panels with panels made of glass fiber reinforced concrete (GFRC), precast concrete, and spandrel glass. These panels were assessed across two variables — insulation (or “R value”) and area. The results showed that the aluminum panel assembles had the highest CO2 impacts, followed by FRP, with precast concrete having the lowest impacts. The group also showed that CO2 impacts increased as R-value was increased; this was especially true for the FRP panels due to the use of EPS foam as primary insulation (versus fiberglass used for other panels). Finally, the authors recommended that Kresyler look into the use of polyester resin within the manufacture of their FRP panel laminates, as this was found to be the most significant source of carbon emissions.

A Comparative Life Cycle Assessment of Commercial Roofing Options

Robert Firme, Kelsey Gerhart, Pablo Lopez, Marcos Vidal, Daniela Urigwe

The group conducted an LCA to determine the relative impacts of two commercial roofing system alternatives to restore a failing roof in Southern California — a full replacement with a new built-up roof with R-36 insulation and 30-year life, and a 30 percent replacement maintaining R-24 insulation with 20 years more of useful life. The group found that the 30 percent replacement option had a slightly lower life cycle cost and environmental impact profile despite its lower lifetime. The group found that this result was largely driven by lower material needs — there was not a significant difference in the use phase energy consumption between the two options due to a temperate climate. The authors conclude that partial roof replacement may be the best alternative for commercial buildings, and that efforts should be made to incorporate recycled roofing material into new production to further reduce environmental impacts.

Life Cycle Assessment Final Report: Cultured Marble vs. Natural Marble

Xinsheng Chu, Jingzhi Wang, Dan Wei, Jieming Wei, Nanyu Zhao

This group conducted an LCA to compare impacts from a cultured marble panel wall against a traditional natural marble wall. The group assessed a functional unit of 1 m3 of marble panel wall used in a hotel in Palo Alto for a 20-year life. The group found that cultured marble had significantly lower life cycle impacts — the main reason for cultured marble’s environmental impacts was the polyester resin used in its manufacture, while the transportation of the natural marble was the key driver. Differences in life cycle cost were minor, although cultured marble had a slightly lower cost. The authors conclude that cultured marble was the best option to minimize harmful environmental impacts and life cycle costs; the material could be further improved by using recycled polyester within the manufacturing stage.

PPG

Eric Chang, Chandler Kemp, Andrew J. Klein, Kelly Marren, Carol Owens

This report, commissioned by PPG to evaluate electric wind turbines for which they produce fiberglass, represents an LCA of two lawn trimmers — one electric and one gasoline-powered. The group compared the two engines using a functional unit of one “trimmer-hour,” use on the Stanford campus over an eight-year life. Environmental impacts were split between the two products — the electric trimmer had a higher impact within human health impact categories, while the gas trimmer had a significantly higher global warming potential. Results also showed that the majority of impacts came from the use phase (fuel consumption for the gas trimmer, and electricity consumption and manufacturing of lithium ion batteries for the electric trimmer). The life cycle cost for the electric trimmer was found to be lower, due to high fuel costs. The authors recommend more widespread use of electric trimmers, especially if mitigating manufacturing measures are taken, such as moving battery production to the U.S. (which has a cleaner electricity mix).

Life Cycle Assessment of New Fiber Reinforced Composite Steel and Epoxy Steel Dowel Bars for Plain Jointed Concrete Pavement

Sara Barrett, Jon Buhangin, Michelle Burback, Jessica Jimenez, Tyler Weinbrecht

The authors conducted an LCA to compare Fiber Reinforced Polymer (FRP) composite steel dowel bars as an alternative to epoxy dowels for jointed plain concrete pavement transverse reinforcement, in order to determine the best economical and environmental solution based on a 30-year life for epoxy and 60-year life for FRP composite. The group assessed the manufacture, installation and replacement of the two bars, and completed a traffic study assessing speed reduction emissions around the construction zone. Their results suggested that over a 60-year life, FRP composite bars are a better choice in regards to cost and environmental impact — they found that the main driver of these results was the replacement necessary within the epoxy dowel scenario.

Life Cycle Analysis of the MIT Rapid Deployment Shelter

Jason Gabbard, Eric Herbert, Colin Mitchell, Dawn Moore, Sarah Saxon

The group worked in conjunction with the Core Composites research group at MIT to assess the life cycle impacts of a thermoplastic composite and a thermoset composite for use in rapid deployment shelter currently under development. These two composites were compared with the Oriented Strand Board (OSB) structure currently in use. Analysis indicated that OSB had significantly higher environmental impacts than the plastic composite alternatives; the thermoplastic shelter had the least impacts, and the key driver of impacts was the construction phase. Due to the longer service life of the plastic composites, the plastic composite shelters also had a lower life cycle cost; however, the OSB shelter had a higher thermal resistance and thus resulted in lower monthly energy consumption. The authors recommended further attention to this point, which would maximize consumer value in addition to minimizing environmental and economic life cycle costs.

Life Cycle Assessment to Compare the Impact and Costs of DurahStyle™ Sorgum and Bamboo Architectural Panels

Katherine Fitzgerald, Anne McPeters, Shovan Rath, Camilo Cabrera, Victoria Sims

The group conducted an LCA to assess and quantify the life cycle processes, costs and environmental impacts for ChloroFill® DurahStyle™ architectural panels, a material made from sorghum and formaldehyde-free resin and meant to be a sustainable alternative to traditional wood panels. The group compared the sorghum panel to a comparable bamboo panel. They found that the sorghum panel resulted in consistently lower environmental impacts (particularly its global warming potential, a full order of magnitude lower than bamboo). Major drivers were found to be fossil fuel use in transportation and electricity during manufacturing. The sorghum panels also had lower life cycle costs. The authors suggest that as the panels are still under development, further improvements can be realized by sourcing sorghum closer to factory locations and offsetting fossil fuel use (such as through purchase of renewable energy credits).

Panelite ClearShade Window Life Cycle Assessment: ClearShade Window vs. Double Low-E Window

Yang Ji, Hang Li, Wenli Yang, Hong Zhang, Minyan Zhang

Panelite manufactures the ClearShade window with a honeycomb core in between two layers of glass, as an optimal solution to daylight and solar heat control. This group compared ClearShade with Double Low-E Windows using a functional unit of a two-story office building in Pheonix. For both window systems, the building energy consumption within the use phase was the largest driver of environmental impacts; ClearShade performed better during the use phase, but had a larger environmental impact during the manufacturing phase, mostly due to transportation of the honeycomb core from Europe. ClearShade Windows also had lower life cycle costs. The group also performed a sensitivity analysis and found that the initial results held constant despite varying building location, window area and window type.

Evaluation of Wool Barriers and Chemical Additives for Fire Protected Furniture: A Life Cycle Assessment for the Sustainable Furnishings Council

Alma Al-Quqa, Megan Ashjian, Annette Fleishman, Alison Ignatowski, Anna Weiser-Woodward

This study evaluated the environmental and human health impacts associated with two flame-resistant alternatives to traditional chemical flame retardants — EcoWool, an organic wool barrier, and Fyrol™ A710, a non-halogenated chemical flame retardant — for protection of two upholstered dining room chairs. The results showed that Fyrol™ A710 resulted in higher total emissions and significant human health concerns (particularly carcinogenic emissions) compared to EcoWool. However, do to small-scale, labor-intensive manufacturing processes, the EcoWool was almost 40 times more expensive over the full life cycle of the product. The authors suggest that significant government intervention and labeling requirements may affect these drivers of cost in the future.

Life Cycle Assessment of the Lunar Regolith Bio-Composite and Comparison with the Production of Concrete Bricks

Caroline Nowacki, Flavia Grey, Patricia AuBuchon, Pratyush Havelia, Satej Desai

The group conducted an LCA of a Lunar Regolith Bio-Composite brick (a mixture of a bovine protein-based solution with volcanic dust currently being investigated by NASA for construction on the lunar surface) in order to compare its energy, emissions and cost impacts with traditional concrete masonry unit (CMU). Use phase was not considered (due to lack of data about the lifetime of the lunar brick). The lunar regolith brick was found to have far more severe environmental impacts, mostly driven by the processing of the Bovine Serum Albumin (BSA). The cost of developing these bricks was also several orders of magnitude higher than CMU. However, the authors found that this large price discrepancy could be mitigated through recycling of the BSA and volcanic dust, the major cost drivers. The authors finally recommend that NASA investigate other proteins or varieties of fine-grained particulate that may be less cost- and energy-intensive to manufacture.

Life Cycle Analysis of the Agri-Pod Farm Project: Prepared for AVI Consulting, Inc and the Massachusetts Institute of Technology

Clay Griggs, Ethan Heil, Raymond Pierson, Wiratama Ramanto, Christina Sedighi

The Agri-Pod is a modular growing facility for high-density agriculture, built using prefabricated panels made from a polystyrene foam core and an outer layer of thermoset-fiberglass composite. This group conducted an LCA for Agri-Pod kale production compared with conventional organic farming. The Agri-Pod system was found to have significantly higher GHG emissions and solid waste impacts than conventional farming; the lighting was the main driver of these impacts. The Agri-Pod grown kale was also calculated to be significantly more expensive over a 50-year lifespan. However, the authors caution that the life cycle impact assessment may not fully capture the context and implications of these two systems — for example, Agri-Pods consume less than half the water of traditional farming, which may be much more valuable in a water-poor context.

Life-Cycle Assessment Report: Next-Generation Hog Farrowing Facilities using Thermoplastic

Jacob Englander, Henry Lippincott, Nicole Schuetz, Doug Weiss, Mark Wittman

The group conducted an LCA in partnership with MIT to assess the impacts of using thermoplastics to redesign a next-generation hog farm, a very resource-intensive industry. A comparison was isolated to the hog farrowing building, and compared a barn designed and manufactured out of conventional materials with the thermoplastic design over a 20-year life. The MIT group targeted a 30 percent reduction in use phase energy with the new materials and design, which was used by the group to model the use phase within the LCA. Overall, environmental impacts for the next-generation barn were considerably lower due to efficiency of materials and construction; the model also estimates a roughly 30 percent reduction in life cycle costs for the next generation barn compared to conventional. The authors found that the thermoplastic material was the primary driver of emissions, and provided the MIT group with several scenarios that could guide their design considerations.

Welded Wire Fabric vs. Fiber Reinforced Concrete: A Life Cycle Assessment of Façade Panels

Gerrit de Moor, Axel Guyon, Moiz Kapadia, Anna Kovaleva

This group compared two competing types of concrete panels used in building facades — steel welded wire fabric (WWF) reinforced panels and fiber reinforced concrete (FRC) panels — using the functional unit of a panel designed to meet building codes in San Francisco over a lifetime of 60 years. A structural analysis was performed to determine the design and material criteria for two panels of comparable strength. The group found that FRC panels outperformed WWF-reinforced panels in every aspect of the impact assessment and represented lower life cycle costs. The group determined that the main driver for these results was the fact that the FRC panels only had to be half as thick (no corrosion protection layer was needed), in addition to concrete’s energy and carbon-intensive manufacturing process.