- The Washington Times - Tuesday, September 19, 2006

Anyone who ever tried to dig a hole in January knows how hard the cold earth can be. However, underneath that top layer of soil, the earth is a warmer, more constant temperature no matter what the calendar says.

Home builders are starting to take advantage of that by introducing geothermal heat pumps into homes new and old. The concept is simple and dates to the 1800s, but not until the 1940s did any buildings start delivering on its promise.

Traditional furnace and air-conditioning systems have to work harder than geothermal systems and expend more energy to keep homes comfortable, supporters of the technology say. In the summer, the sticky, hot air is brought to a cooler temperature via air-conditioning units, and the home furnace kicks in come winter to make the crisp air tolerable.

Geothermal heat pumps, however, use the Earth’s natural stasis temperature — an average of roughly 58 degrees — to heat and cool homes more efficiently. As any green builder will quickly point out, the Earth’s heat is a renewable resource.

These heat pumps work through a series of pipes built as a loop installed underneath a house. During winter, fluid carrying the Earth’s natural heat pumps through the pipes and into a home’s indoor geo-exchange device. That releases warmer air into the home, typically through duct fans placed throughout the house.

Come spring and summer, the process reverses itself. Heat is drawn from the home via the piping loop and absorbed by the ground. The process works like a refrigerator, which draws heat from its interior to keep perishables cool, according to the District-based Geothermal Heat Pump Consortium Inc.

Geothermal heat pumps run quietly and usually are installed in a basement or attic. They also are far more energy-efficient than existing temperature systems and produce lower utility bills as well.

The catches with the system are less than with such other renewable energy sources such as wind and solar power. The systems are more expensive to install than traditional heating and cooling units, but sources say the units pay for themselves within five to seven years.

Many contend that utility bills drop dramatically with these systems.

Glenn Chinery, a mechanical engineer with the Environmental Protection Agency’s Energy Star program, calls geothermal heat pumps a “good, mature technology.”

“If you’re in a mild climate like San Diego, it’s not worth it … but if you’re in a Nashville or Atlanta, it can really save a lot of money,” Mr. Chinery says.

Installers can introduce the heat pumps in one of two ways, either via vertical or horizontal drilling. The former is better in places where homes are tightly packed, such as in the District.

Mr. Chinery lives in a Silver Spring condominium in which the building uses geothermal heat pumps.

“The utility bills are extremely low,” Mr. Chinery says, adding that each drilled well where the piping tunnels under his building is a few inches in diameter.

Lisa McArthur, assistant director with the Oklahoma-based International Ground Source Heat Pump Association, says that though the energy concept remains the same for these heat pumps, technology has improved the way they work.

Newer models feature better grouting for thermal conductivity and dual compressors for the interior parts of the system to make them even more energy-efficient, Miss McArthur says.

Many pipe manufacturers guarantee their products for 50 years, she adds.

Homeowners looking to retrofit their houses with geothermal units can do so without abandoning their furnaces, if they wish.

“It’s not an either-or proposition,” she says.

The misconception many people have regarding the systems involves their price tag.

“People say it’s a rich man’s technology,” says Miss McArthur, who retrofitted her 1,600-square-foot home with a geothermal unit. “The upfront cost was a little more than a traditional system, but my utility bill was immediately cut in half.”

Prices for these heat pumps can vary significantly based on the potential system’s design, brand and method of digging (vertical or horizontal), according to the Geothermal Heat Pump Consortium.

Generally, a system will run between $3,000 and $5,000 per ton, or the total heating and cooling load. Consortium communications manager Jessica Commins says a typical 1,800-square-foot house would have a 3-ton load, but that amount might be different depending on the design and overall efficiency of the house.

The systems aren’t just for homeowners.

Miss McArthur says inner-city homes and building retrofits “are very doable.” “You only need a minimum amount of room, and the industry has gotten creative.”

District-based architect Chris Landis used geothermal heat pumps for a four-story, 20,000-square-foot home improvement center about to open in Northeast. A project of that scale required that he drill 22 vertical wells that were 375 feet deep, figures far greater than the average home would need.

Initially, Mr. Landis figured the payback period in energy savings would come in about seven years, but with energy prices jumping in recent months, he figures that period could shrink to as low as three years.

John Byrd with Home Fronts News says in a standard home there might be one drilled loop that goes down about 40 feet.

The process of retrofitting a home for geothermal heat pumps can take two days for the drilling and pipe installation, and parts of a homeowner’s lawn may be overturned in the process.

Mr. Byrd says geothermal heat pumps first caught fire in the late 1970s because of energy concerns. Recent news headlines, assuming the latest dip in gas prices is temporary, could reignite interest in the technology.

Bill Asdal with New Jersey-based Asdal Builders, says there’s a “great curiosity” among homeowners surrounding geothermal heat pumps.

“The consumer interest, whether it’s about technological intrigue or the marketing power of the green movement, it’s on the radar,” Mr. Asdal says. “People aren’t automatically going to gas versus oil.”

Though the number of new homes using the heat pumps is rising, the majority of homes in his region are constructed by builders who appear less interested in the technology. For Mr. Asdal, that’s a shame because he says he feels confident about the systems and their benefits.

“We’ve had it around for 20 years. It’s seamless. I have not seen long-term downsides,” he says.



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