The Champaign-Urbana Mass Transit District (CUMTD) is installing a geothermal heating, ventilation, and air conditioning (HVAC) system with funding from the TIGGER Program. This $450,000 project will reduce the fossil fuel used for the 15,000 square foot CUMTD administration building while cutting overall greenhouse gas emissions.

The geothermal system is designed to reduce energy consumption by creating a closed loop system to tap normal ground temperatures. This geothermal HVAC installation uses indoor water source heat pumps along with a glycol-and-water solution to exchange heat between the Earth and the heat pumps via a ground loop. The system takes advantage of the natural heat storage capacity of the ground, providing cooling by moving heat to the ground as a heatsink, while allowing heating by extracting heat from the ground. The ground loop will be installed in a series of vertical boreholes with thermally enhanced grout buried nearby to fully exploit the natural heat exchange process underground.

Geothermal HVAC is a proven technology with widespread acceptance, particularly in hot and cold climates where building operators face high heating and cooling costs. In its Upper Midwest location, CUMTD is faced with both cold winters and hot summers, and geothermal HVAC is a cost-effective alternative to conventional heating and cooling designs.

Compared to the current HVAC system, the new system will reduce electrical energy usage by 40%, cut natural gas usage by 60%, and decrease carbon dioxide greenhouse gas emissions by 133 metric tons. The reduced emissions will directly improve local air quality and help CUMTD operate its business at a lower cost.