NPPD RELEASES REPORT ON SHS GEOTHERMAL
December 17, 2007
The Nebraska Public Power District released a review of the geothermal system in Scottsbluff High School. The report comes after the building has relied on a ground source heat pump system for three full school years. Ground source heat pumps use the earth’s stable temperatures to provide a source of heat when in heating mode and provide a heat sink when in cooling mode.
There was a dramatic decrease in natural gas usage since the implementation of the system, and electrical energy usage increased. This increase in electrical energy is to be expected as the school switched from natural gas heating to ground source heat pumps with the added air-conditioning. According to the report, the significant note was that even with the addition of air-conditioning and ventilation, the cost to operate the facility had decreased significantly.
In 2002, Scottsbluff High School used approximately 1.033 million kilowatts of electricity and 109,942 therms of natural gas. In 2006, the building used approximately 1.772 million kilowatts of electricity and 20,616 therms of natural gas. The cost of energy per square foot in 2002 was $0.84 compared to $0.60 in 2006.
The report also figured the amount saved in 2006 by using the energy usage of 2002 with the energy costs in 2006. If the district had not switched to the ground source heat pump, the district could have paid an estimated $171,624 compared to the $96,501 it did pay. That’s over $75,000 in savings.
During the review, NPPD observed many features that provided for energy efficiency. Some of those features included: a direct digital control system to allow setting of room temperatures and operating schedules from one central location; energy recovery ventilators which temper the outside air brought in for ventilation; and two rooftop units in the gym, one in standby to only operate during large occupant loads.
While the report was very complimentary of the current system, NPPD offered other strategies that may have the potential to save ten to twenty percent more money. Most of these strategies included changing different operating system schedules.
“We were very pleased with the results of the report,” commented Bill Knapper, Scottsbluff Public Schools Director of Business Services. “I believe we will continue to see energy and cost savings and have sent the recommendations to our engineering firm for further analysis.”
For the complete report click here.
