Monitored Performance of Residential Geothermal Heat Pumps in Central Texas and Southern Michigan,
SANDIA NATIONAL LABS ALBUQUERQUE NM
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This report summarizes measured performance of residential geothermal heat pumps GHPs that were installed in family housing units at Ft. Hood, Texas and at Seifridge Air National Guard base in Michigan. These units were built as part of a joint Department of DefenseDepartment of Energy program to evaluate the energy savings potential of GHPs installed at military facilities. At the Ft. Hood site, the GHP performance was compared to conventional forced air electric air conditioning and natural gas heating. At Selfridge, the homes under test were originally equipped with electric baseboard heat and no air conditioning. Installation of the GHP systems at both sites was straightforward but more problems and costs were incurred at Selfridge because of the need to install ductwork in the homes. The GHPs at both sites produced impressive energy savings. These savings approached 40 for most of the homes tested. The low cost of energy on these bases relative to the incremental cost of the GHP conversions precludes rapid payback of the GHPs from energy savings alone. Estimates based on simple payback no inflation and no interest on capital indicated payback times from 15 to 20 years at both sites. These payback times may be reduced by considering the additional savings possible due to reduced maintenance costs. Results are summarized in terms of 15 minute, hourly, monthiy, and annual performance parameters. The results indicate that all the systems were working properly but several design shortcomings were identified. Recommendations are made for improvements in future installations at both sites.
- Non-electrical Energy Conversion
- Air Conditioning, Heating, Lighting and Ventilating
- Logistics, Military Facilities and Supplies