Doctoral Dissertations
Date of Award
12-2025
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Energy Science and Engineering
Major Professor
Xiaobing Liu
Committee Members
Bo Shen, Fangxing Li, Zhili Zhang
Abstract
Buildings account for approximately 40% of total energy consumption in the United States, with space heating and cooling representing a major share. Heat pumps, which provide both heating and cooling, are being adopted at an accelerating rate, surpassing gas heating sales. However, their widespread deployment remains constrained by performance limitations in extreme climates, high capital costs, and increasing stress on the electric grid. This dissertation introduces advancements and novel technologies for residential heat pumps to address these challenges. It investigates multiple strategies—building envelope improvements, dual-source heat pumps, and thermal energy storage for load shifting and demand response—to enhance efficiency, reduce capital cost, and support grid flexibility.
First, the effect of air-sealing in single-family houses on the life-cycle cost of deploying geothermal heat pumps in these buildings across the U.S. was investigated. Results show that reducing outdoor air infiltration from 0.8 to 0.35 air changes per hour in single-family houses can lower total borehole length needed to meet thermal loads by up to 55% and reduce electricity consumption for space heating by up to 44%.
Second, a dual-source heat pump (DSHP) concept was developed that enables the system to utilize both air and ground as heat sources or heat sinks for space conditioning. This approach reduced the required total borehole length by up to 40% compared to conventional geothermal heat pumps and decreased total electricity consumption by up to 50% compared to air-source heat pumps.
Third, the integration of air-source heat pumps with thermal energy storage was analyzed to evaluate load-shifting potential under different phase-change material temperatures. When scaled to all single-family houses in Texas, this configuration was found to reduce annual peak electric load by 1.7%, translating to hundreds of millions of dollars in potential savings of the electric grid infrastructure development.
Finally, a novel geothermal heat pump system incorporating diurnal thermal storage was proposed to leverage ground heat exchangers for short-term energy storage, achieving up to 30% reduction in total borehole lengths required for meeting thermal demands.
Collectively, these studies advance residential heating and cooling technologies and contribute to the development of efficient, affordable, and flexible heat pump systems that deliver thermal comfort at lower cost while enhancing electric grid resilience.
Recommended Citation
Anees, Fady, "Advancing Residential Heating and Cooling: Innovations in Heat Pumps, Energy Storage, and Load Shifting. " PhD diss., University of Tennessee, 2025.
https://trace.tennessee.edu/utk_graddiss/13579