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Doctoral Dissertation: Decarbonization pathways for buildings via product replacement, end of life management, and energy demand response

Event Type
Lixi Liu, Ph.D. Candidate
Center for Sustainable Systems
School for Environment and Sustainability
August 28, 202012:00pm - 1:00pm


Buildings represent 10% of global carbon emissions from fossil fuels. Consuming 40% of U.S.’s total energy consumption and poised to provide demand flexibility to the grid, buildings represent a substantial opportunity for energy conservation, grid modernization, and renewable integration. Beyond energy, reverse logistics (reuse, remanufacturing, and recycling) and material efficiency are vital to conserve important but limited natural resources (e.g. specialty metals) that many energy-efficient and renewable technologies depend on. This dissertation advances methods of life cycle analysis and data analytics while addressing opportunities in three key aspects of building energy and technologies – how to choose better products, how to better manage products at their end of life, and how to use energy more effectively.

Chapters 2 and 3 examine the keep vs. replace conundrum using the replacement of residential and commercial lighting, in which the rapidly changing LED technology creates unclear tradeoffs with incumbent technologies in terms of cost, energy savings, and emissions. Chapter 4 assesses the value of reverse logistics by comparing the life cycle impacts of recovering rare earth and critical metals from commercial lighting waste, and of extended use and modular (component) replacement of lighting systems. Chapter 5 conducts piecewise log-linear-Fourier regressions on whole-home smart meter and outdoor temperature data to disaggregate space heating and cooling loads and estimate the technical thermal demand response potentials in the Midwest. By examining these aspects of building energy use and technologies, this research helps inform decision making for building managers and energy consumers while providing industry with insights on product design, reverse logistics, and demand response program design.


Lixi Liu is a Ph.D. candidate in Mechanical Engineering and Environment and Sustainability, a Rackham Merit Fellow, and an NSF Graduate Research Fellow. She received her BS in Mechanical Engineering from Kettering University in Flint, MI, and her MS in Mechanical Engineering and Sustainable Systems from the University of Michigan in Ann Arbor. She is currently a part-time residential buildings research analyst at the National Renewable Energy Laboratory in Golden, CO. Her research interests include grid interactive efficient buildings, low-income housing improvement, energy use decarbonization, product adoption and diffusion, and life cycle optimization.

Chairs: Prof. Gregory Keoleian & Prof. Kazuhiro Saitou