With the cost of energy rising and many businesses finding themselves in a financial pinch one local school system may have found a way to keep costs down.
Colorado Springs School District 11 recently implemented a pilot program whereby a building’s heating and cooling is produced by a geothermal method. The guinea pig for the project is a new 24,000-square-foot facilities building in eastern Colorado Springs. Located at 5240 Geiger Blvd., it was completed last November. The Environmental Protection Agency reports that this GeoExchange system has an efficiency advantage of nearly 40 percent, as well as 30 percent lower maintenance costs, said Thomas Fernandez, energy manager for School District 11.
“It seems to me to be one of the industry’s best kept secrets,” said Fernandez, who introduced the system to District 11 officials three years ago after attending a geothermal energy conference. “If you take the lower operating costs with the lower maintenance costs … now you have quite a significant difference. It’s almost too good to be true.”
The system takes heat from the ground and forces it into a building via a series of pumps. The network begins with four “zones” with eight bores — or deep holes — per zone. In the case of the facilities building, 1.5-inch plastic polyethylene pipes run 300 feet deep into the ground under the parking lot, where underground temperatures average about 50 degrees Fahrenheit year-round. The pipes then elbow back up to join with the main system.
The four zones transport a 3-to-1 mixture of water and methanol simultaneously, then join above ground at the main pump. As the fluid flows through the ground pipes, its temperature rises, said Fernandez. The 7.5 horsepower main pump operates in a manner similar to a refrigeration unit because it generates a higher temperature with aid from the condenser.
The fluid, now at a much higher temperature of about 100 degrees, flows through the above-ground steel pipes and into individual heat pumps, where a thermostat in each heat pump controls the amount of heat released into the rooms. These heat pumps are small and can be mounted in the ceiling cavity. Pipes connect one unit to another and each pump can service two or three rooms.
The cooling cycle is similar, said Fernandez, when the refrigerating cycle is reversed and heat is extracted out of the room via the pump and put back in the ground.
“We have this vast quantity of heat in the ground that’s just sitting there, waiting for someone to use it,” said Fernandez. “You use electricity to extract it. It’s not totally free, but it’s very efficient.”
This closed-loop system prevents inner pipe corrosion as well as the introduction of contaminants. If a pipe were to break, there would be no concern about toxicity because the antifreeze used is environmentally friendly and the zone could be shut down, allowing for repair while maintaining the building’s constant temperature.
The initial cost for the system was $181,897, compared with $116,480 for a conventional heating and cooling system. However, after adding in the average annual heating cost of $7,286 ($12,127 for conventional), cooling cost of $5,024 ($8,530 for conventional), and maintenance cost of $2,601 ($9,991 for conventional), the total cost during the 20-year life cycle for the GeoExchange system would be $544,216 compared with $763,947 for the conventional system.
Fernandez secured a feasibility-study grant from the Department of Energy in efforts to promote the technology. There is only one other school system in Colorado that utilizes geothermal exchange. Located in Bethune School District in Kit Carson County, that system was installed in 1993. More than 1,200 schools in the United States use this heating and cooling system.
Fernandez hopes to incorporate this method in new District 11 schools scheduled to be built in the northeast area of El Paso County within a couple of years. If it remains an efficient and cost-saving system, he would like to see existing schools in District 11 retrofitted as well.