Geothermal Heat Pump System Chosen
OPPD recently conducted a study to determine the most energy-efficient heating–and-cooling system for three dormitories at Offutt Air Force Base, and the geothermal heat pump system came out on top.
The evaluation considered and compared three HVAC alternatives to the existing system to determine which was the most energy efficient.
One of the dormitories was built in 1961, and has an attached dining hall that supports all three facilities. This building has 112,000 square feet of space and 282 dormitory rooms. The other two facilities were built in 1987, and have an identical floor plan with 73,500 square feet of space and 180 dormitory rooms. All the buildings were being heated and cooled with a chiller and boiler with a fan coil system.
Through the evaluation, OPPD considered and compared three HVAC alternatives to the existing system to determine which was the most energy efficient: a geothermal heat pump system, water-source heat pump system or an upgrade of the existing system. Each alternative would provide superior comfort levels over the existing system.
OPPD personnel directed computer-based simulation of the dormitories, using an energy-simulation program. Drawings of each of the buildings and their mechanical rooms, along with other pertinent data and measurements of the facilities, were used to generate the model for the evaluation.
Analysis results indicated that the geothermal heat pump system was the most energy-efficient alternative. The geothermal system ranked highest primarily because it eliminated natural gas as a heating source. With fluctuating gas prices, an increasing number of institutions have taken advantage of high-efficiency geothermal heat pump technology to control their energy costs.
The geothermal systems tap a virtually inexhaustible source of renewable energy deep beneath the ground. Because they move heat to and from the earth, with proper energy efficient design and installation, fossil fuel consumption for heating or cooling is dramatically reduced. Geothermal systems are not only cost-effective, but good for the environment, according to the Department of Energy and the Environmental Protection Agency. In addition, the systems have lower maintenance costs.
A conventional water-source heat pump system also would be an improvement over the existing equipment. A comparison of energy consumption for each heating-and-cooling system is shown below.
Comparison of performance results for each heating and cooling system
(Click here for a printable version of the table.)
There are several points that need to be considered when reviewing the performance results of these systems. The cooling capacity of the new systems will be 37 percent higher than the current equipment. The capital costs to implement each of these systems were not considered.
Offutt Air Force Base Dormitory Case Study
Click here for a PDF version of the full case study. (Link will open in a new window.)
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This project was partially financed by the U.S. Department of Energy through a Special Projects grant awarded to the Nebraska Energy Office from the State Energy Program. Any opinions, findings, conclusions or recommendations are those of the author(s) and do not necessarily reflect the views of the Department of Energy or the Nebraska Energy Office.
For a more comprehensive copy of this report or for an evaluation and recommendation for your HVAC equipment, please call an OPPD energy management engineer at (402) 636-3536 in Omaha or 1-800-648-2658 outside the metropolitan area.
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