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ABSTRACT
The purpose of this study was to perform a county-level analysis to identify the economically favorable regions in the US. for using ducted air-source heat pumpsfor space heating in residential buildings. The most common configurations of heatpumps include a backup heat source to maintain adequate heating capacity when the outdoor air temperature drops below 30-35°F (-1 to 2°C) and is either an electric resistance strip or a fossil-fuelfiredfurnace. Both of these supplemental sources are less efficient modes of heating the home than using heatpump mode only, and result in increased operating cost for the homeowner; but they are nonetheless necessary due to the degradation of heating capacity and efficiency of the heatpump at reduced outdoor air temperatures. The lifecycle cost of the heat pump can vary depending on the specific type of backup used in addition to otherfactors such as geographical differences in annual energy usage, upfront cost of the equipment, and the local utility rates of the fuel source. In the current research, the economics of a heat pump are calculated based on county level energy consumption data and state level variation in equipment and fuel costs, and compared against the economics of a central AC and natural gasfurnace, which is the most common type of space-conditioning equipment used in the country today. Our results show that in warm southern states such as Texas and Georgia, and in regions with favor-able electric to natural gas price ratios like the Pacific Northwest, heat pumps with electric backup are more economical than the baseline technology of central AC and natural gas furnace. In the northern climates, colder temperatures increase the run times of strip-heat mode, causing all-electric heat pumps to be less cost-competitive. In contrast, dual-fuel heat pumps with natural gas furnaces as the backup heat source were found to be cost-competitive throughout much of the United States. The results of this analysis provide electric utilities with insights that can be used to prioritize their building space heating electrification efforts.
INTRODUCTION
The primary space heating equipment in more than 60% of homes in the United States uses fossil-fuel as the energy source (Energy Information Administration 2015). Deployment of heat pumps for the heating of buildings is an energy-efficient way to shift the nation's energy...