Geothermal system to heat & cool Colonnades
What’s an earth-friendly way to cool down a residence hall? Take energy from warm indoor air and drop it hundreds of feet underground. Elon University started work this summer on a geothermal field that will heat and cool the Colonnades residence halls near the Koury Business Center, including three buildings scheduled to open in July 2011.
The project requires drilling 112 holes, at 6 inches in diameter and 440 feet deep. Once drilled, a loop of high-density plastic pipe is pushed into each hole. The hole is then backfilled with gravel and grout.
Water flows through the pipe from the pump house in a closed loop that never enters ground water.
In the summer, refrigerant circulated through the air conditioning system will carry away heat from the buildings and to an energy converter in the pump house. The energy converter passes the heat to the water in the closed loop well system, which then transfers the heat to the ground.
The reverse takes place in the winter. With temperatures below ground warmer than air temperatures, the heated liquid returns to the buildings to provide comfortable living space.
Elon staff members overseeing the construction project say the system will reduce the university’s consumption of fossil fuels and anticipate it paying for itself in the coming years, depending on increases in energy prices.
“But this wasn’t done solely on a payback basis,” said Neil Bromilow, director of planning, design and construction management at Elon. “This was done as an environmental priority. It does pay for itself, but the payback period depends on the price of natural gas.”
Three machines have been working on the geothermal field since late June. Bromilow said it takes about a full day for each well to be drilled. Wells will be connected in groups of seven, with the groups converging on a common manifold for refrigerant distribution to the residence halls.
After the loop pipes are routed to the manifold, and substantial construction to the three new residence halls is complete, workers will lay dirt over the field and plant grass to create a commons area for recreation. No sign of the system will be visible without looking in the pump house.
Several American colleges and universities have installed geothermal systems in recent years to heat and cool a variety of structures, from residence halls to academic buildings.
“This system is one of several steps the university is taking to reduce greenhouse gas emissions,” said Elaine Durr, Elon’s sustainability coordinator.