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Local Community Goes Green "Underground"

Posted: Oct 1, 2012 9:11 PM by Karl Roskamp
Updated: Oct 1, 2012 9:59 PM

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COLUMBIA - What is a group of Columbia residents doing that 95 percent of Americans are not?

An intentional community dubbed Terra Nova, which prides itself on ecologically friendly living, found the answer under their feet. Terra Nova uses ground source heating to cover all their heating and cooling needs.

"We can keep the thermostat at any temperature we like year round," Terra Nova member Claire Garden said.

Ground source heating, unlike geothermal heating, does not rely on the Earth's core for heat; instead, it uses groundwater or soil to provide the heating and cooling. The process doesn't just provide heat and air conditioning; it does so efficiently.

"Ground source heat pumps statistically have been documented to probably be the most efficient investment you can make in terms of energy," O2 Geothermal partner Jim Oakley said, who installed ground source heating for his own home.

"Your largest loads in your house for energy usage are heating, air conditioning and heating water and a ground source heat pump can do all those things."

Heat pumps work because heat wants to travel from something that's warm to something that's cold. During installation, a contractor will drill horizontal or vertical loops into the ground. A vertical system, which is used by Garden and Terra Nova, is preferred when there isn't a lot of land to install the loops. The drilling will go 100 to 400 feet deep in a vertical system.

More land is required for workers to install a horizontal system, but it's installed at a shallower depth of five to ten feet and is more cost-effective.

Once installed, the loops are filled with a liquid such as water and ethanol. If the liquid is colder than the surrounding Earth, it will absorb the heat and use it to warm up the home it's serving. The system can be reversed to provide cooling.

Despite upfront costs that may deter potential buyers, ground sourcing heating holds up against the competition.

"A ground source heat pump is far more efficient than either an air heat pump or gas furnace," Garden said.

Even though air pumps are cheaper, they aren't as effective in the winter, according to Oakley. The air pumps have to exert more energy to convert freezing air into to heat while ground source heat pumps work when the Earth has temperatures between 55 to 57 degrees year round.

Using ground source heat pumps can also reduce dependence on gas and electricity that is normally used for heating and cooling. That would be the case for Garden and Terra Nova members, but their electric needs are already covered by their 38 solar panels.

"We're very much dedicated to getting green energy if we can and to being as energy efficient as we can," Garden said.

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