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Michigan Capitol undergoing energy efficiency measures expected to save $250,000 a year

As part of the first-ever American Clean Power Week, MI Environment looks at the geothermal project underway at the Michigan Capitol building.

The Michigan Capitol building has been undergoing renovations that include installation of a geothermal system that will cool and heat the building. It is believed to be the largest geothermal system at any U.S. Capitol building.

Geothermal exchange systems use the constant 54-degree temperature of the earth as a heat source in the heating season and as a heat "sink" for heat rejection in the cooling season. The heat rejected into the ground in the summer can be recaptured to heat the building in the winter. The result is a heating and cooling system that is unmatched in efficiency and environmental impact.

Installation of the system involved drilling 272 bore holes that reach approximately 500 feet in depth. The system is filled with polypropylene glycol, a vegetable grade glycol. That way, if a leak were to occur, it would not harm the ground and/or aquifer below.

In addition to the geothermal system, the Capitol Infrastructure Project also include retrofitting the entire building with LED light bulbs that will help cut electric usage.

The Capitol's annual utility bill has averaged $800,000 a year. With the upgrades, a savings of 30 to 35 percent is projected. Total savings are estimated to be $250,000 a year.

Keep up to date on the Capitol Infrastructure Project on the Michigan State Capitol Restoration website.

Photo caption: Two of the four drilling rigs boring holes for the Capitol's new geothermal system. The field will contain 224 bores, each of which is 500 feet deep.

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