With energy costs and environmental awareness rising, builders can effectively market the installation of ground-source energy options to homeowners.

Our first experience with direct-exchange geothermal left us with a great impression. We're looking for the opportunity to do the next one," says Dave Brandt, one of the fourth-generation owners of Bakersfield, Calif.-based Brandt Homes. The homebuilding firm, which constructs about 30 homes a year in the $500,000 to $1 million range, recently cut its teeth on the newest geothermal technology -- direct exchange or DX -- when it invited local expert and installer Glenn Bland, owner of Bland Air Conditioning and Heating, Inc., to equip a client's home with an EarthLinked geo system.

Despite summer temperatures of 110°F or more, the home's system performs at a remarkable 350 percent to 400 percent efficiency, meaning that it gives the homeowner three-and-a-half to four units of energy for every unit of electricity it consumes.

"We now recommend this type of system to our customers," adds Brandt. "There are so many pluses -- the elimination of noisy outdoor condensing units, super-high efficiency and dramatically reduced utility bills, quick payback of the initial cost and the environmental advantages."

Nearby, Palm Springs, Calif.-based Contempo Homes is soon to embark on three upscale Zero Energy residential developments with a total of 141 homes, all of which provide EarthLinked DX geothermal systems and solar heat as standard equipment. Sheila Cobrin, director of governmental affairs for Contempo Homes, says that approvals for the subdivision are underway, and the list of buyers is growing steadily.

Three thousand miles away and four years earlier, Del Leese sensed a looming energy crisis. He made the decision to install a geothermal heating and cooling system when the family constructed its new home in Mechanicsburg, Pa. Now, while many of his neighbors are experiencing record high electric and gas utility bills, Leese and his family are enjoying savings.

After months of research -- which entailed comparisons of water-sourced and DX geothermal systems and interviews of installing contractors -- Leese settled on a direct-exchange, EarthLinked heating and cooling system.

The type of system we're talking about -- at the cutting edge of heat pump technology -- is offered by two firms (ECR Technologies, Inc. and American Geothermal DX) that separated from the pack to develop higher efficiency DX technology.

Last year, Leese paid only $650 (about $55 per month) for heat, air conditioning and hot water in his 3,200-square-foot home. When compared to the average $220 per month that his neighbors are paying for these services in homes of about the same size, a quick calculation reveals that Leese is saving more than 70 percent on utility expenses. It's typical of what he's seen during the past three years.

"Our previous home had electric baseboard heat and window air conditioning units. It was terribly inefficient, and rather uncomfortable at that," says Leese. "Today, the comfort is seamless and smooth, year-round and entirely reliable. We're delighted with the geothermal system.

"We decided before moving in that we would separately monitor the system's energy use," adds Leese. "For four years now, we've seen how it gives us four to five units of energy for every unit of electricity it consumes."

Manufactured by Lakeland, Fla.-based ECR Technologies, Inc., Leese's system efficiently taps the Earth's abundant energy through direct contact with the Earth. The system harvests heat directly from the Earth, which maintains a constant temperature of about 52°F in central Pennsylvania. While air-source heat pumps rely on a wide range of ambient air temperatures, the Earth's constant temperature provides a much more favorable source for heating and cooling.

Jody Hoffman of Hoffman Mechanical installed the 3-ton (42,000 BTU), 14-loop DX system for the Leese home by drilling 14 21¼2-inch diameter holes at 45-degree angles to depths of 50 feet.

From the variety of loop configurations available for a DX system, Hoffman and Leese chose the diagonal method, which disturbs the least amount of Earth. For homes where ground space is limited, or especially for existing homes with mature landscaping, this configuration is ideal because all of the small-diameter drilling takes place from a shallow, six-square-foot pit, with drill holes radiating outward and down at an angle from the base of the pit (see figure 1).

"Most geothermal systems operate at ranges of 250 percent to 350 percent efficiency," says Hoffman, who has installed many types of geothermal heating and cooling systems for more than 20 years. "With the variety of options available for installation of the Earth field, and the highest operational system efficiencies, up into the 400 percent range, conservatively, DX is a great choice for many homes or buildings."

While some geothermal systems rely on plastic piping to transfer water and antifreeze through a plastic loop and an intermediate heat exchanger, DX technology circulates a refrigerant through highly conductive copper Earth loops that are inserted into bore-holes of 50 or 100 foot depth, then embedded in a protective thermal grout that enables direct transfer of energy with the Earth.

DX and water-source geo systems usually run about the same installed cost -- usually several thousand dollars more than a conventional, air-to-air heat pump -- though with DX you'd see better operating efficiencies and, possibly, something akin to "surgical insertion" of the ground loops. The process of getting the tubing in place for a DX system is faster and far less invasive to the property, making it possible to retrofit homes with mature landscaping.

Although not yet familiar to everyone, ground-source heat pumps have been installed for more than 30 years and are recognized as a highly efficient heating and cooling system. "Geothermal heat pump technology offers a renewable energy solution that's right for almost any home," says Gemma Tiller of Air Brokers HVAC based in Branson, Mo. "Thermal energy of sufficient temperatures anywhere in the U.S. and Canada is harvested from the Earth and transferred into buildings by a heat pump that provides heating and cooling."

Even for builders constructing homes of small parcels, chances are it's their best hedge against an energy crisis. Thermal energy is stored in the ground, ready to be used. "Newer technology extracts it with greater ease, with little disruption to the surrounding landscape, and at such high operating efficiencies; it makes payback on the investment faster than ever before," adds Tiller.

A ground-source unit works like a conventional heat pump to cool and heat a home or business. The key difference between an air source and ground-source heat pump is that the ground-source unit harvests the stable and renewable heat from beneath the Earth's surface.

"The equipment transfers virtually endless thermal energy from the Earth into the home during the winter months and transfers excess heat from interior spaces into the Earth where it's stored during the summer," says Bland.

As a result, a ground-source unit saves energy, which reduces greenhouse gas emissions and can cut utility bills by up to 70 percent. And, very little maintenance is required. Surveys of ground-source owners conducted by the Geothermal Heat Pump Consortium show that they rank their systems higher in comfort than do the owners of other heating and cooling systems, and more than 95 percent say they would recommend ground-source to friends and family members.

Operational Efficiencies & Cost

A comparison of operating cost of geothermal systems vs. other heating/cooling systems is impressive. In an insulated new home of 2,436 square feet in Chicago with a family of three in the home 12 hours a day, the cooling load is 24,717BTUs per hour, and the heating load needed is 43,668BTUs/hour. This includes energy for heating of all domestic hot water for clothes washing, bathing, etc. (See chart on p. 30.)

Tiller, who has experience installing all types of geo systems, prefers DX technology because the refrigerant lines are placed in direct contact with the heat source without the need to pump water through an intermediate heat exchanger. These systems are well suited for new construction and retrofit installations with Earth loops installed vertically, diagonally or horizontally.

Typically, any geothermal system provides service for up to 25 to 30 years, which is twice the life expectancy of air source heat pumps. This is because the stable heat source avoids thermal stresses to the compressor, the enclosed unit is out of the weather, and no fossil fuel is burned by the system.

All-in-one System for Hot Water

In addition to interior heating and cooling, many geothermal systems can provide a third function, which is to heat a home's domestic water by one of two means: through integrated full-time water preheating, or through "desuperheating" water heating.

Integrated water heating (on demand) uses the heat pump system to heat water at any time of the year. Its first cost is higher, but it provides operating savings all year.

Because this water-heating option has the full heat pump system capacity available to heat water, it can provide quicker recovery than an electric resistance water heater.

A desuperheater reclaims heat from the air conditioning cycle to heat water. Its first cost is lower. Savings are realized in the cooling season by transferring waste heat to the hot water storage tank. Even in the heating mode, the desuperheater can provide preheating to the water heater, reducing the work required of the electric resistance elements.

A desuperheater provides free water heating throughout the summer season and typically reduces water heating costs from 40 percent to 60 percent, depending upon the amount of cooling required.

John Vastyan is a Manheim, Pa.-based journalist and communications professional whose work focuses on the plumbing and mechanical, radiant heat and geothermal industries.