An energy and cost analysis of residential ground-source heat pumps in Iowa

Abstract

The objective of this study was to evaluate residential ground-source heat pumps throughout the state of Iowa and use that information to develop educational opportunities for prospective ground-source heat pump owners. The ground-source heat pumps were evaluated based on performance, efficiency, and economics. The study was limited to similar homes throughout the state of Iowa, recent constructions (1997 to 2001), and vertically or horizontally configured loops. Energy audits were conducted for each home to obtain building characteristics. Using the characteristics, heating and cooling loads were estimated for each home. Utilizing the heating and cooling loads along with utility bill and weather information, performance data were calculated for each home. The energy analyses showed that cooling loads are not accurately tracked using this method as a result of occupant schedules. The heating load performance showed that there is a negligible difference between the performance of a vertical and horizontal loop system. The economic analysis evaluated the cost difference between using a ground-source heat pump and natural gas furnace. The analysis showed that a significant amount of money could be saved during the heating season when using a ground-source heat pump. It was determined that several homeowners were interested in the installation of a ground source heat pump but did not fully understand the technology. An extensive literature review was completed and an educational document was produced for homeowner’s education. Homeowners tend to be highly interested in estimating the amount of money that can be saved using a ground-source heat pump. To estimate a home’s annual savings using a ground source heat pump in comparison to other means of conditioning a home, a savings calculator was developed. The calculator was able to closely estimate most homes evaluated in this study.