Digging for heat lowers bills

By Barbara Maynard
Correspondent

With winter approaching and energy rates not getting any lower, homeowners are looking for ways to reduce their utility bills. Some have turned to Mother Earth to provide their heating and cooling needs.

Geothermal heat pump systems rely on the constant underground temperature of the earth to supply heat in the winter and absorb heat in the summer. In return, the environment reaps the benefits of reduced fossil fuel combustion.

Instead of producing heat by burning fossil fuels, a geothermal system moves heat from one place to another - from the ground to a home. Once installed, these systems don't look much different from traditional furnaces, except they are often smaller and include a pipe running out of the house into the ground. Under frost line, the ground is a constant temperature of about 52 degrees year-round along the Front Range. Geothermal systems, also known as ground source heat pumps, extract this heat by pumping a mixture of water and ethanol (for antifreeze) through buried tubes. After circulating through the tubes, the liquid has been warmed by the earth and returns to the house. At 52 degrees, this liquid is obviously not warm enough itself to heat the house adequately, so the heat is extracted and concentrated by a heat pump and then transferred to either air, for a forced air system, or to another liquid, for radiant floor heating. After passing off its heat, the cooled water/ethanol mixture returns to the ground for another cycle.

The system works in reverse in the summer, removing heat from the house and transferring it to the cooler ground. Adding to the energy savings, hot water heaters can use the heat removed from the house in the summer and any extra heat generated in the winter.

Geothermal systems are not "off the grid" - they require a conventional 220V circuit to run the pump, compressor and fan. However, because the energy they use for heating is supplied from the ground, they are extremely efficient.

"For every BTU that I buy to run the compressor, I get three free from the earth," said Monte Schmidt of GeoSource Distributors Inc. in Longmont.

Geothermal systems are more expensive to install than traditional heating and air conditioning, but they pay for themselves down the road in terms of lower energy bills. Savings vary depending on what the alternative heat source was, the size of the system and other variables, but heating and cooling costs are expected to be in the neighborhood of 30 to 60 percent lower annually, according to the U.S. Department of Energy.

In addition to long-term financial savings, many people are motivated by the environmental benefits of using such an efficient system. According to Schmidt, replacing a conventional heating and cooling system with a geothermal unit has a similar effect on carbon dioxide levels over the life of the system to taking two cars off the road or planting 750 trees.

Environmental concerns motivated Tammie Gregori of the Solar Ridge development in northwest Fort Collins to have Schmidt put a geothermal system in her new home three years ago.

"We wanted to not use more than our share of the world's natural resources," she said. "Geothermal is easy to do in a new house and makes a lot of sense - it's extremely efficient. Everyone says you've got to put in one of those 95 percent efficient furnaces. Well, I say 'I've got a 300 percent efficient system, why would I want to do that?'"

Pat Plank, a member services representative with Poudre Valley Rural Electric Association, estimated that there are 40 to 50 residential units installed in the cooperative's coverage area. "Everybody is tickled pink," he said. "They like the systems. I've never run across anybody who didn't."

Geothermal systems are often paired with a back-up heat source, such as a traditional furnace, to supplement on the coldest winter days. "A ground source heat pump system can be designed and installed to provide 100 percent of all needs for any building," Schmidt said. "However, the additional cost to do that creates a circumstance where the system isn't as economically beneficial as it could be."

Schmidt scales systems to provide the best financial benefit for a given situation, which is influenced by what the back-up source of heat is (propane, natural gas or electric), what the goals of the owner are (some people prefer to use geothermal for 100 percent of their heat because of the environmental benefits), and the home construction and soil type.

Gregori said that her backup heat, an electric heater integral to the system, has never been used.

Costs vary, but an installation for a 2,000-square-foot home, designed to provide about 95 percent of the heating needs, could cost about $18,000. Schmidt says he can accommodate most budgets, since even smaller systems designed to cover less of the heating load will still provide energy savings.

Homeowners considering a geothermal system should choose an installer carefully. The systems are designed specifically for each home, and a poor design or installation can greatly affect the efficiency of the system. Plank recommends that people contact either their local utility or the Geosource Heat Pump Consortium for references.

To help defray the cost of geothermal systems, Poudre Valley REA offers rebates to homeowners who apply within six months of installation. Fort Collins Utilities doesn't offer rebates targeted at geothermal specifically, but commercial customers can qualify under the Electric Efficiency Program, which provides incentives for projects that reduce summer demand. Depending on the application, geothermal systems can reduce peak demand compared with traditional air conditioning.

Gregori hopes to take the environmental benefits of her system one step further in the future. "My hope is that we can someday put photovoltaic panels on the house to provide enough electricity to run the system."

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