Residential and commercial buildings represent 39% of global energy carbon emissions. In the U.S., buildings consume 40% of the total energy consumption and thus represent a substantial energy saving opportunity. Additionally, building energy flexibility, or the ability to reduce or move demand to a different time, is playing an increasingly important role in grid modernization and renewable integration by helping to balance supply. Material efficiency is another foundation to sustainability, as many energy-efficient and renewable technologies depend on the use of specialty materials, which are dwindling in supply and many face geopolitical conflicts. This dissertation advances methods of life cycle analysis and data analytics while addressing some of these issues and opportunities in three key aspects – how to choose better products, how to better manage products at their end of life, and how to use energy more effectively. Chapter 2 and 3 examine the keep vs. replace conundrum by studying the replacement of residential and commercial lighting, in which the rapidly changing LED technology creates unclear tradeoffs with incumbent lighting in terms of cost, energy savings, and emissions. The results suggest that while LED lighting offers competitive performance and life cycle cost as fluorescent lighting, there is less advantage (or benefit) for immediate LED adoption in a lower use, upfront cost-sensitive, or slowly decarbonizing grid situation. Chapter 4 evaluates the life cycle impacts of recovering rare earth and critical metals from spent linear fluorescent and LED fixtures, respectively. This chapter also assesses the impacts of extended use and modular (component) replacement to assess the value of reverse logistics (reuse, remanufacturing, and recycling). The results show that both types of metal extraction create net environmental impacts, which can be mitigated with process optimization and waste preprocessing to increase extraction efficiency. While modular replacement leads to overall lower environmental burdens, full replacement can offer incentive for LED recycling as their metal-heavy housing structure and heat sink are attractive to recyclers. Chapter 5 performs piecewise log-linear-Fourier regressions on whole-home smart meter data and outdoor temperature data to disaggregate the thermostatically controlled loads from whole-home consumption and to estimate the technical thermal demand response potentials in the Midwest. The results suggest that single family buildings, being the higher energy users and larger customer base than multi-family, can provide higher per customer and aggregated demand flexibility. However, multi-family buildings, particularly those with a central HVAC system, may have the advantage of pooled demand across multiple units and should therefore be considered accordingly. By examining the three decision-making questions related to technology and product selection (Chapter 2 - 3), waste management and material recovery (Chapter 4), and energy use and demand response (Chapter 5), the research helps inform decision making for building managers and energy consumers, and provide industry with insights regarding product design, reverse logistics, and demand response program recruitment.
CSS Publication Number:
life cycle optimization
life cycle assessment
multiple change-point regression
Liu, Lixi. (2020) “Improving Building Sustainability: Lighting Life Cycle Optimization and Management, and HVAC Demand Response.” Doctoral Dissertation, University of Michigan: Ann Arbor: 1-130,