Electrical energy and demand savings from a geothermal heat pump energy savings performance contract at Ft. Polk, LA

Abstract

At Fort Polk, LA the space conditioning systems of 4,003 military family housing units have been converted to geothermal heat pumps (GHP) under an energy savings performance contract (ESPC). At the same time, other efficiency measures, such as compact fluorescent lights (CFLs), low-flow shower heads, and attic insulation, were installed. An independent evaluation of the Fort Polk ESPC was carried out. Findings indicate that the project has resulted in a 25.6 million kWh savings in electrical energy use, or 32.4% of the pre-retrofit electrical consumption in family housing, for a typical meteorological year. Peak electrical demand has also been reduced by 6,541 kW, which is 39.6% of the pre-retrofit peak demand. Natural gas savings are about 260,000 therms per year. In addition, the ESPC has allowed the Army to effectively cap its future expenditures for family housing HVAC maintenance at about 77% of its previous costs. Given these successful results, the Fort Polk ESPC can provide a model for other ESPCs in both the public and the private sectors. The purpose of this paper is to outline the method by which the ESPC was engineered and implemented, both from the standpoint of the facility owner (the US Army) and the energy services company (ESCO) which is carrying out the contract. The lessons learned from this experience should be useful to other owners, ESCOs and investors in the implementation of future ESPCs. It should be noted that the energy savings presented in this document are the apparent energy savings observed in the monitored data, and are not to be confused with the contracted energy savings used as the basis for payments. To determine the contracted energy savings, the apparent energy savings may require adjustments for such things as changes in indoor temperature performance criteria, additions of ceiling fans, and other factors.