Rutherford County Schools has found a natural way to conserve energy and keep schools cool at the same time.
When Rockvale Middle School opens for the new school year, the $22 million, 160,000-square foot facility will be warmed and cooled by geothermal energy.
Rockvale Middle will be open to the public from 2-3:30 this afternoon for a ribbon cutting and dedication ceremony. The dedication will be held in the auditorium. An open house and refreshments will follow.
The new middle school is part of RCS’s long-term plans to open more middle schools across Murfreesboro, including one in the Buchanan area and another near Oakland High School.
“Rockvale was badly needed because of the growth in the Highway 99 corridor, in the Highway 96 area and in Christiana,” RCS Spokesman James Evans said. “The school will open with some room for growth, but we expect it won’t be long until most of these seats are filled.”
When it officially opens to students the first day of school Monday, Aug. 11, 750-800 of the 1,000 seats will be filled with students who will be warmed and cooled by green technology.
It saves thousands
Rutherford County Schools started putting geothermal heating, ventilating and air conditioning (HVAC) system in newly constructed schools about three years ago, explained Gary Clardy, assistant superintendent of Engineering and Construction.
Stewarts Creek Elementary and Middle schools, as well as La Vergne Lake Elementary have the systems in place.
“It is more expensive on the front end but in the long term you save money on the energy savings,” RCS Spokesman James Evans said.
The systems run between $750,000 to $1 million for new construction, but take six to seven years to pay back the upfront cost, Clardy said.
Geothermal systems save money because they are some of the most energy efficient HVAC systems available with a typical utility cost savings of up to 50 percent.
For example, Murfreesboro City Schools put a geothermal HVAC system in John Pittard Elementary School, which opened last year, and saw the school’s heating bill cut in half.
Between August 2007 and February 2008, MCS spent an average of $29,774 to heat and cool Scales Elementary, which has the exact same square footage as Pittard Elementary and a traditional HVAC system. During the same period, the city school system only spent $14,093.27 at Pittard.
Pittard only cost MCS $4,320.33 for natural gas over the six-month period. By comparison, it cost MCS $92,754.90 for natural gas at Scales.
Pittard even saw a cost savings on electricity usage by using 376,300 fewer kilowatt-hours than Scales. That translates into a more than $21,000 in electricity savings over the first six months the geothermal system was in use.
Broken down to average utility cost, it cost $0.1066 per square foot to heat and cool Pittard and $0.2251 per square foot to do the same at Scales.
“We’re getting similar or a little bit better than that,” Clardy said, adding RCS has lowered ceiling heights to reduce the volume of air that must be conditioned and uses tinted windows to save more in energy cost.
RCS has also outfitted new schools and retrofitted old ones with low-watt florescent lights to further reduce electricity consumption.
It’s the wells
The geothermal system saves so much money because outside air doesn’t have to be heated or cooled.
“You’re not taking 90 to 100 degree outside air and trying to cool it. Or taking 28 degree air and warming it,” Clardy said. “It’s taking less energy to heat or cool.”
The backbone of geothermal HVAC systems is wells drilled between 300-350 feet into the ground, where the temperature is a constant 58 degrees Fahrenheit.
Rockvale has 285 geothermal wells scattered around its campus in bore fields, which can be found under the school’s parking lots and ball fields, further conserving space.
A refrigerant is piped through the wells where it takes on the constant ground temperature and is pumped back into a central processing room.
From there the refrigerant is pumped to air conditioning units for each classroom, where it passes through coils that either take away or add heat, depending on whether the unit is set to heat or cool.
Individual units then re-circulate air from classrooms – with some fresh air mixed in – over the coils to condition the air. So air only has to be warmed or cooled a few degrees to keep a steady temperature throughout the school.
Maintenance cost is also kept low because the well pipes, the most complex and expensive piece of the system, have a 100-year warranty.
“Basically you don’t have anything to go wrong …” explained Trey Lee, project manager. “We’re just dealing with a few fans and pumps.”
RCS plans to use the same technology in all future schools, including Brown’s Chapel Elementary that will open next year and two new middle schools that are in development.
Michelle Willard can be contacted at 615-869-0816 or mwillard@murfreesboropost.com.
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