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Retrofitting existing buildings shows promise for reducing energy consumption and greenhouse gas emissions. However, selecting the appropriate energy retrofit strategy (or strategies) requires careful planning, detailed information about a building’s current condition and historical energy consumption patterns, and evaluation of multiple retrofit options. One retrofit strategy, using phase-change materials (PCMs) as a relatively straightforward means of increasing the thermal mass of an existing building, continues to be of interest to building owners, operators, and utilities alike. Despite the seeming ease of installation (e.g., PCMs can be layered on top of existing acoustical ceiling tiles rather than removing drywall to add insulation to exterior walls), a few primary factors need to be considered before applying PCMs in existing buildings. This paper presents a novel process for selecting PCMs for building energy retrofits, comprising an evaluation of both the candidate building as well as the PCM. This process includes goal setting for the energy retrofit as well as the PCM installation, evaluation of an existing building to ensure that it is a good candidate for PCM integration, and, finally, analyzing the energy-savings potential of PCM integration as a retrofit strategy. This process was developed based on the results of five case studies conducted by the authors, including three experimental commercial building PCM installations as well as simulation results from two residential buildings. The authors present how the application of this process would have changed the choices made by stakeholders involved in the cases studied, thereby avoiding some of the less desirable results of those projects. [ABSTRACT FROM AUTHOR]

The increasing residential air-conditioning demand and the growing number of solar photovoltaic (PV) systems installed in the residential sector have increased electrical net energy demand fluctuation. These severe fluctuations lead to a need for flexible generation capacities that can rapidly meet the fluctuating demands. To combat these fluctuations, utility companies have introduced different price plans to financially incentivize customers to reduce their demand during certain hours of the day, in essence, attempting to make residential electricity demand constant (or "flat") for the daytime hours. Flattening the net demand not only reduces homeowners' operation costs, it also enhances stability of the electricity grid by decreasing the need for flexible generation plants that typically use more fossil fuels. Therefore, shifting electricity consumption from peak to off-peak hours promotes economic and environmental savings. This paper leverages simulation modeling and experimental work to explore the feasibility of coupling precooling with photovoltaics (PVs) to achieve flat residential net demand in three Phoenix, AZ area homes. Results show that precooling coupled with PVs provides economic benefits of up to $160 annually for homeowners while simultaneously reducing demand fluctuations by up to 90%. [ABSTRACT FROM AUTHOR]

As air-conditioning demand has increased significantly during the last decade, efficient energy use has become more important due to large electric power demands and limited reserves of fossil fuel. Electrical energy use fluctuates significantly during a 24-hour day due to variable demand from industrial, commercial, and residential activities. In hot and cold climates, the dominant part of the load fluctuation is caused by cooling and heating demands, respectively. If electric loads could be shifted from peak hours to off-peak hours, not only would building operation costs decrease but the need to run peaker plants, which typically use more fossil fuels than non-peaker plants, would also decrease. Thus, shifting electricity consumption from peak to off-peak hours promotes economic and environmental savings. This paper uses simulation and experimental work to examine 12 precooling strategies in three residential buildings in the Phoenix, Arizona, climate. The selected buildings are considered to represent the majority of residential buildings in the area. Results of this project show that precooling can save up to 46% of peak energy demand in a home constructed with concrete or cementitious block and up to 35% in wood frame homes. Homeowners can save up to U.S. $244/year in block construction and up to U.S. $119/year in wood frame homes. [ABSTRACT FROM AUTHOR]

Using sensible heat storage (SHS) in buildings with high thermal mass can support energy efficiency; in retrofits, as well as in buildings with lower thermal mass, using SHS might not be feasible due to the lack of thermal mass required to maintain comfort in a volume of air (i.e., in a room within a building). Therefore, applying Latent Heat Thermal Storage (LHTS), such as Phase Change Materials (PCM), can be more effective to enhance these buildings’ thermal behavior. PCMs have a high heat of fusion; during the phase change between solid and liquid, a large amount of thermal energy can be stored and released in these materials. This paper presents a detailed analysis of PCM behavior seen in sample retail buildings located in Arizona, a hotdry climate. This paper presents the impact of air circulation in the plenum space, on PCM efficacy and energy performance. This paper comprises experimental work as well as EnergyPlus model results to determine the factors that can increase the efficacy of PCM integration. In particular, results indicate that air circulation in the plenum promotes convection heat transfer between the air and the PCM sheets, resulting in reduced energy consumption. Finally, the paper evaluates cost saving potential for consumers, as well as the potential for peak load reduction for utility providers. [ABSTRACT FROM AUTHOR]