Date of Award


Document Type


Degree Name

Master of Science


Department of Systems Engineering and Management

First Advisor

Alfred E. Thal Jr., PhD


The world is undergoing a dramatic transformation with regard to how it produces and consumes energy due to increasing demand from developing nations and diminishing new resource discoveries. In addition, there has been increased concern over the effect of carbon dioxide emissions on the environment. All of these issues have created a combined pressure to force the world to begin to redefine how energy is utilized. Geothermal or ground source heat pumps (GSHPs) may provide one potential solution to these problems. This research investigated vertical borehole closed-loop GSHP systems in direct comparison to natural gas furnaces combined with traditional air-conditioning (NGAC) for 51 locations in the United States. The study utilized Trane Trace 700, Geothermal Loop Design, and Building Life-Cycle Cost 5 software packages for analysis. Although the installation costs for GSHP systems were 257% higher than NGAC systems, the operating costs were 33% lower. The mean simple and discounted payback periods for the GSHP system were 10 and 15 years, respectively. Carbon dioxide emissions were found to be 2.2% higher for the GSHP systems due to their use of coal-fired electricity in most locations. The overall life-cycle cost was 19.0% lower when selecting the GSHP system over the NGAC system.

AFIT Designator


DTIC Accession Number