Geothermal Smart Solutions
| * Geothermal Overview
| * Making Hot Water
| * What is GeoExchange Technology
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| * How does it work?
| * Benefits for home/building owner
| * Does it work in very cold or hot climate?
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Geothermal Residential, Commercial, Schools
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Homeowners in virtually every region of the United States are enjoying a high level of comfort and significantly reducing their energy use today with GeoExchange (geothermal) heating and cooling.
This marvelous technology relies primarily on the Earth's natural thermal energy, a renewable resource, to heat or cool a house or multi-family dwelling. The only additional energy GeoExchange systems require is the small amount of electricity they employ to concentrate what Mother Nature provides and then to circulate high-quality heating and cooling throughout the home.
Homeowners who use GeoExchange systems give them superior ratings because of their ability to deliver comfortably warm air, even on the coldest winter days, and because of their extraordinarily low operating costs. As an additional benefit, GeoExchange systems can provide inexpensive hot water, either to supplement or replace entirely the output of a conventional, domestic water heater.
GeoExchange heating and cooling is cost effective because it uses energy so efficiently.1 This makes it very environmentally friendly, too. For these reasons, federal agencies like the Environmental Protection Agency and the Department of Energy, as well as state agencies like the California Energy Commission, endorse it.
Owners of GeoExchange systems can relax and enjoy high-quality heating and cooling year after year. GeoExchange systems work on a different principle than an ordinary furnace/air conditioning system, and they require little maintenance or attention from homeowners. Furnaces must create heat by burning a fuel--typically natural gas, propane, or fuel oil. With GeoExchange systems, there's no need to create heat, hence no need for chemical combustion. Instead, the Earth's natural heat is collected in winter through a series of pipes, called a loop, installed below the surface of the ground or submersed in a pond or lake. Fluid circulating in the loop carries this heat to the home. An indoor GeoExchange system then uses electrically-driven compressors and heat exchangers in a vapor compression cycle--the same principle employed in a refrigerator--to concentrate the Earth's energy and release it inside the home at a higher temperature. In typical systems, duct fans distribute the heat to various rooms.
In summer, the process is reversed in order to cool the home. Excess heat is drawn from the home, expelled to the loop, and absorbed by the Earth. GeoExchange systems provide cooling in the same way that a refrigerator keeps its contents cool--by drawing heat from the interior, not by injecting cold air.
GeoExchange systems do the work that ordinarily requires two appliances, a furnace and an air conditioner. They can be located indoors because there's no need to exchange heat with the outdoor air. They're so quiet homeowners don't even realize they're on. They are also compact. Typically, they are installed in a basement or attic, and some are small enough to fit atop a closet shelf. The indoor location also means the equipment is protected from mechanical breakdowns that could result from exposure to harsh weather.
GeoExchange works differently than conventional heat pumps that use the outdoor air as their heat source or heat sink. GeoExchange systems don't have to work as hard (which means they use less energy) because they draw heat from a source whose temperature is moderate. The temperature of the ground or groundwater a few feet beneath the Earth's surface remains relatively constant throughout the year, even though the outdoor air temperature may fluctuate greatly with the change of seasons. At a depth of approximately six feet, for example, the temperature of soil in most of the world's regions remains stable between 45 F and 70 F. This is why well water drawn from below ground tastes so cool even on the hottest summer days.
In winter, it's much easier to capture heat from the soil at a moderate 50o F. than from the atmosphere when the air temperature is below zero. This is also why GeoExchange systems encounter no difficulty blowing comfortably warm air through a home's ventilation system, even when the outdoor air temperature is extremely cold.2 Conversely, in summer, the relatively cool ground absorbs a home's waste heat more readily than the warm outdoor air.
Studies show that approximately 70 percent of the energy used in a GeoExchange heating and cooling system is renewable energy from the ground. The remainder is clean, electrical energy which is employed to concentrate heat and transport it from one location to another. In winter, the ground soaks up solar energy and provides a barrier to cold air. In summer, the ground heats up more slowly than the outside air.
GeoExchange systems can also provide all or part of a household's hot water. This can be highly economical, especially if the home already has a GeoExchange system, hence a ground loop, in place.
One economical way to obtain a portion of domestic hot water is through the addition of a desuperheater to the GeoExchange unit. A desuperheater is a small, auxiliary heat exchanger that uses superheated gases from the heat pump's compressor to heat water. This hot water then circulates through a pipe to the home's water heater tank. In summer, when the GeoExchange system is in the cooling mode, the desuperheater merely uses excess heat that would otherwise be expelled to the loop. When the GeoExchange unit is running frequently, homeowners can obtain all of their hot water in this manner virtually for free. A conventional water heater meets household hot water needs in winter if the desuperheater isn't producing enough, and in spring and fall when the GeoExchange system may not be operating at all.
Because GeoExchange systems heat water so efficiently, many manufacturers today are also offering triple function GeoExchange systems. Triple function systems provide heating, cooling and hot water. They use a separate heat exchanger to meet all of a household's hot water needs.
A Wise Choice
GeoExchange is a smart investment for consumers who want a system that provides a high level of comfort and low monthly energy bills for as long as they own their homes.
Common Questions
What is GeoExchange technology?
GeoExchange technology uses the earth's renewable energy, just below the surface, to heat or cool a home or other building, and to help provide domestic hot water. It's sometimes referred to as a geothermal heat pump, a ground source heat pump, or earth energy. No matter what you call it, GeoExchange systems are the best choice you can make for both your pocketbook and your planet. In fact, these systems are so good that the U.S. Environmental Protection Agency (EPA) has said they are, "the most energy-efficient, environmentally clean, and cost-effective space conditioning systems available today."
A few feet beneath the surface, the earth's temperature remains fairly constant year-round, ranging from 45º or so in northern latitudes to about 70ºF in the deep south. GeoExchange takes advantage of this constant temperature to provide extremely efficient heating and cooling.
In winter, a fluid 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 the interior space for 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 fluid in the ground loop then carries the heat back to the earth. The only external energy needed for GeoExchange is the small amount of electricity needed to operate the heat pump, ground loop pump and distribution fan or pump.
Is GeoExchange new?
The basic technology has been around for more than 50 years, and many homeowners and businesses have been enjoying the benefits of GeoExchange for much of that time.
In recent years, though, significant improvements have been made in the materials used, installation methods, electronic control systems, and the efficiencies of the compressors, pumps and other equipment.
What are the major benefits to the home/building owner?
Owners enjoy lower utility bills (25% to 70% lower than with conventional systems), lower maintenance, and higher levels of comfort, year-round. They also have the peace of mind of knowing they're being environmentally responsible.
Since a GeoExchange system burns no fossil fuel on-site 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 or building. 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.
What are the environmental advantages?
According to data supplied by the U.S. Department of Energy (DOE) Office of Geothermal Technologies, nearly 40% of all U.S. emissions of carbon dioxide (CO2) are the result of using energy to heat, cool and provide hot water for buildings. This is about the same amount of CO2 contributed by the transportation sector.
A typical 3-ton residential GeoExchange system produces an average of about one pound less Carbon Dioxide (CO2) per hour of use than a conventional system. To put that in perspective, over an average 20-year lifespan, 100,000 units of nominally sized residential GeoExchange systems will reduce greenhouse gas emissions by almost 1.1 million metric tons of carbon equivalents.
That would be the equivalent of converting about 58,700 cars to zero-emission vehicles, or planting more than 120,000 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.
How popular is GeoExchange?
There are more than one million installations in the United States today. Although this is a very small percentage of the total HVAC market, the number of people who are choosing to install GeoExchange is growing rapidly as more learn about the technology.
Is GeoExchange used primarily in homes?
While many homes have been fitted with GeoExchange systems, a large number of commercial enterprises, including factories, retail stores, office buildings and schools also use GeoExchange to save energy and protect the environment. In fact, there are more than one million installations in the United States today.
According to the U.S. Environmental Protection Agency (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 Carbon Dioxide (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.
Will GeoExchange work in a very hot or very cold climate?
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?
Not necessarily. It depends on how you measure cost. While they sometimes 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.
Furthermore, the energy efficiency of the system adds value to the home. The National Association of Realtors Appraisal Journal estimated that a home's value increases by $10 to $25 for every $1 reduction in utility bills. That's a lot of equity to build just by choosing GeoExchange !