Estimated maintenance cost savings from a geothermal heat pump energy savings performance contract at Fort Polk, Louisiana

At Fort Polk, Louisiana, the space-conditioning systems of an entire city (4,003 military family housing units) have been converted to geothermal heat pumps (GHPs) under an energy savings performance contract. At the same time, other efficiency measures, such as compact fluorescent lights, low-flow hot water outlets, and attic insulation, were installed. These retrofits were performed by an energy services company at no up-front cost to the Army. The company has also assumed responsibility for maintenance of all the equipment installed. In return, it receives a percentage of the energy and maintenance savings realized by the Army. In developing the energy savings performance contract, the Army estimated its pre-retrofit maintenance costs from bids received on a request for proposals. In this paper, a more rigorous cost estimate is developed, based on a survey of maintenance records for the pre-retrofit HVAC equipment. The reliability of the equipment is also estimated using an actuarial method to determine the number of units requiring replacement each year and the effect of these replacements on annual maintenance costs.