Margaret A. Cargill Philanthropies (MACP) last year celebrated the opening of a 66,777-square-foot addition that included a geothermal exchange system for heating and cooling office space.
Finance & Commerce
March 7, 2017
Frank Jossi
Margaret A. Cargill Philanthropies (MACP) last year celebrated the opening of a 66,777-square-foot addition that included a geothermal exchange system for heating and cooling office space.
MACP is one of a handful of organizations in Minnesota that have installed geothermal systems over the last few years. Although geothermal exchange systems require a significant upfront investment, the equipment generally lasts for decades and the fuel source, the Earth, costs nothing.
Geothermal exchange systems employ plastic tubing buried in the ground or placed in water to capture the Earth’s steady temperature by circulating a nontoxic liquid that transfers heat to and from the ground. The liquid passes into heat pumps, which through a refrigeration cycle concentrate heat in winter and cools it in summer.
The system at the Margaret A. Cargill Philanthropies office, 6889 Rowland Road, required drilling more than 140 well bores 250 feet deep to create a “vertical loop” connected to heating pumps. The system manages heating and cooling for the new addition while enhancing the performance of the previously existing 28,460-square-foot building, according to Shawn Kinniry, office and facilities manager.
“In the 10 months we’ve been in our expanded building, the system has operated efficiently, effectively, and according to design,” he wrote in an email. “By design, leveraging the Earth’s more constant ground temperatures, especially in this region where we have such wide temperature extremes, provides a jump-start of sorts” to maintaining appropriate temperatures in the building.
“It’s an incredible technology, it’s the technology of the future,” said Gary Connett, Great River Energy’s member and marketing services director. “There’s nothing greener, cleaner and more efficient than a heat pump.”
Many of the 28 members of Great River Energy, a wholesale electric cooperative, give customers rebates for installing geothermal exchange systems. Within Great River’s territory, the systems have installed in 12 schools, a number of churches, civic buildings, and “a few thousand houses,” Connett said.
Karges-Faulconbridge Inc., 670 County Road B W. in St. Paul, worked on the MACP project and several others involving geothermal systems. The engineering company’s own office building has a geothermal exchange system attached to a loop underneath a field next to its parking lot.
The office was a former grocery store built on a site that once served as a city garbage dump, according to Karges-Faulconbridge principal Randy Christenson. Geothermal made sense both as a way to demonstrate the system to clients and to economically manage the office temperature, he said.
Geothermal takes the heat of the earth, roughly 48 degrees in Minnesota, and uses that as a starting point for temperature control inside buildings. “You’re using the Earth, with a constant temperature, for storing heat in the ground in summer and pulling heat back out in winter,” he said.
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