What is Geothermal Heating & Cooling?
Geothermal heating & cooling (also called Geoexchange) uses the earth’s renewable energy, just below the surface, to heat or cool a home or other building, and to help provide hot water.
How does it work?
A few feet beneath the surface, the earth’s temperature remains fairly constant-ranging from 45ºF or so in northern latitudes to about 70ºF in the deep south-year round. Geoexchange takes advantage of this constant temperature to provide extremely efficient heating and cooling.
In winter, a water solution circulating through pipes buried in the ground absorbs heat from the earth and carries it into the home. The Geoexchange system inside the home uses a heat pump to concentrate the earth’s thermal energy and then to transfer it to air circulated through standard ductwork to fill the interior space with warmth.
In the summer, the process is reversed: heat is extracted from the air in the house and transferred through the heat pump to the ground loop piping. The water solution in the ground loop then carries the excess heat back to the earth. The only external energy needed for Geoexchange is the small amount of electricity needed to operate the refrigerant compressor, ground loop pump, and fan.
Is Geoexchange new?
Not really. The basic technology has been around for more than 20 years, and many homeowners and businesses have been enjoying the benefits of Geoexchange for much of that time.
In recent years, though, many improvements have been made in the materials used, the installation methods, and the efficiencies of the compressors, pumps and other equipment.
What are the major benefits to the homeowner?
Homeowners enjoy lower utility bills (25% to 50% lower than with conventional systems), lower maintenance, and higher levels of comfort, year-round. Even more than that, though, they have the peace of mind of knowing they’re being environmentally responsible.
Since a Geoexchange system burns no fossil fuel to produce heat, it generates far fewer greenhouse gas emissions than a conventional furnace, and completely eliminates a potential source of poisonous carbon monoxide within the home. Even factoring in its share of the emissions from the power plant that produces electricity to operate the Geoexchange system, total emissions are far lower than for conventional systems.
Can you be more specific about the environmental advantages?
According to data supplied by the U.S. Department of Energy and EPA, a typical 3-ton residential Geoexchange system produces an average of about one pound less CO2 per hour of use than a conventional system. To put that in perspective, if just one million homes converted to Geoexchange, the country could reduce its CO2 emissions by 8.8 billion pounds.
That would be the equivalent of converting about 587,000 cars to zero-emission vehicles, or planting more than 1.2 million acres of trees.
And the waste heat removed from the home’s interior during the cooling season can be used to provide virtually free hot water-resulting in a total savings in hot water costs of about 30% annually, and lowering emissions even further.
Is Geoexchange used primarily in homes?
Not really. While many homes have been fitted with Geoexchange systems, commercial enterprises, including factories, retail stores, office buildings and schools also use Geoexchange to save energy and protect the environment.
In fact, according to the U.S. EPA, schools are a particularly attractive place for the use of technology. Across the country, schools using Geoexchange right now are saving an estimated $25,000,000 in energy costs-which can be used instead for better educational equipment and more teachers. These schools also save a half-billion pounds of CO2 emissions per year.
Should all of the nation’s schools convert to Geoexchange, the EPA has estimated that we could reduce oil imports by 61 million barrels annually, and provide the same environmental benefits as planting 8 million acres of trees or converting nearly 4 million cars to zero-emission vehicles.
If the same comparison were made across all commercial and residential segments, the potential for environmental benefit would be staggering.
What about a very hot or very cold climate-does Geoexchange work in both?
Yes, Geoexchange technology can be used in any part of the country. Why? Because it transfers heat to and from the earth, which remains at a relatively constant temperature, rather than the air, where temperatures can vary greatly.
Does Geoexchange cost more?
That depends on how you measure cost. While they do cost more to install in homes than conventional systems, because of the ground loop piping, Geoexchange systems typically have the lowest life-cycle cost of any heating and cooling system. Heating and cooling costs for a typical 2,000-sq.-ft. home can run as low as $1 a day.
Moreover, installation costs have declined substantially in recent years, and they’re expected to continue to fall, as more builders and contractors offer Geoexchange systems, and as the industry develops innovative ways to install the systems faster and more efficiently.
Altogether, Geoexchange systems are a sound investment. The amount they save the homeowner every month in energy costs is more than enough to offset their higher installation cost.
Remember, too, that Geoexchange means extra savings on repair, maintenance, and hot water bills. And the energy efficiency of Geoexchange adds value to the home