About 686 miles of ground heat exchanger piping was installed at Fort Polk. The pipe was pre-assembled and installed as “uni-coils,” so the only fusion joints in the piping are near the surface, one of several measures to control installation and maintenance costs. A total of 1.8 million feet of 4-1/8 inch bore was drilled for installation of 3.6 million feet of high-density polyethylene pipe for over 8,000 ground heat exchangers.

Energy Savings: The energy retrofit reduced overall electrical consumption in Fort Polk family housing by 26 million kWh per year (33%) while eliminating altogether annual natural gas consumption of 260,000 therms.

Peak Demand: Summer peak electrical demand was reduced by 7.5 mW (43%).

Load Factor: Electrical energy savings and reduction of peak demand have dramatically improved the annual electric load factor, from 0.52 to 0.62, lowering the total electrical cost to Fort Polk by over $1.0 million per year in addition to the energy cost savings seen at each of the family housing units.

Cost Savings: Fort Polk saves about $345,000 annually for 20 years (the life of the contract). After the contract expires, the Army continues to reap the benefits of the GCHPs’ energy efficiency, about $2.2 million per year, during any remaining GHP service life.

Environmental: CO2 emissions are reduced by 22,400 tons per year.




COPYRIGHT © 2010 GAI, Inc.

Photo No. 3:
Heat Exchanger Installation


In the heating mode GCHPs deliver air to the registers at about 105ºF, which is 10-15ºF warmer than air source heat pumps will do, and warm enough to preclude complaints about the system “blowing cold air.”
An independent evaluation conducted by the Department of Energy’s Oak Ridge National Laboratory ORNL) found that the Fort Polk project was a success by many measures:

Figure No. 1: Pre- and Post-Retrofit Energy Use

en-Solution Member Credits: The “engineer of record” was Richard A. Gordon, P.E. of Gordon and Associates, Inc.; Robert Freeman, Concord Energy Consultants, Inc.; David Fox, CePolk, LLC; Timothy H. Power, The Law Office of Timothy H. Power