Application of Phase Change Materials for Building Energy Retrofits in a Hot Arid Climate

In 2018, building energy use accounted for over 40% of total primary energy consumption in the United States; moreover, buildings account for ~40% of national CO2 emissions. One method for curbing energy use in buildings is to apply Demand Side Management (DSM) strategies, which focus on reducing the energy demand through various technological and operational approaches in different building sectors.

This PhD research examines the integration of DSM strategies in existing residential and commercial buildings in the Phoenix, Arizona metropolitan area, a hot-arid climate. The author proposes three different case studies to evaluate the effectiveness of one DSM strategy in buildings, namely the integration of Phase Change Materials (PCMs). PCMs store energy in the freezing process and use that stored energy in the melting process to reduce the energy demand. The goal of these case studies is to analyze the potential of each strategy to reduce peak load and overall energy consumption in existing buildings.

First, this dissertation discusses the efficacy of coupling PCMs with precooling strategies in residential buildings to reduce peak demand. The author took a case study approach and simulated two precooling strategies, with and without PCM integration, in two sample single-family homes to assess the impact of the DSM strategies (i.e., precooling and PCM integration) on load shifting and load shedding in each home.

Second, this research addresses the feasibility of using PCMs as sensible and latent heat storage in commercial buildings. The author documents the process of choosing buildings for PCM installation, as well as the selection of PCMs for retrofitting purposes. Commercial building case studies compare experimental and simulation results, focusing on the impact of the PCMs on reducing the total annual energy demand and energy cost.

Finally, this research proposes a novel process for selecting PCMs as energy efficiency measures for building retrofits. This process facilitates the selection of a building and PCM that are complementary. Implementation of this process has not yet been tested; however, the process was developed based on experimental and simulation results from prior studies, and it would alleviate many of the PCM performance issues documented in those studies.