Geothermal, or ground source heating, is the direct use of energy absorbed from the sun at the earth’s surface, and supplemented from the earth’s core. The modern geothermal heating and cooling system relies on the stable (55 degrees Fahrenheit) temperature of the earth, or of groundwater in a well, along with an electric heat pump. Water is pumped through tubes buried in the ground, or from a well. In the wintertime this water is warmer than the outside temperature, so the heat pump “extracts” heat from the water to distribute throughout the building, and the now-cooled water is returned to the earth to be re-warmed. The system is reversed in the summer, with the heat pump drawing hot air out of the building, and sending warmed water into the earth to be chilled.
Because a properly designed and installed geothermal system can offer much better efficiencies than electric or gas heating systems, along with longevity, the technology has been recognized internationally and nationally as an intelligent alternative to heating with fossil fuels. See all Geothermal Members.
Interested in installing Geothermal at your home or business? Check out Heatspring Learning Institute’s Informational Survival Kit for the Prospective Geothermal Heat Pump Owner.
Geothermal History and Usage
Geothermal is the oldest naturally occurring resource to be exploited for heating — natural hot springs have been used since the Paleolithic era, in spas since the 3rd Century BC, and for district heating since the 14th Century. The first successful use of a geothermal heat pump, the type of system now widely in use, took place in the 1940’s. Spurred by rising fuel oil costs and estimates (based on current heating expenses) of 30-70 percent savings in heating costs, the number of geothermal installations around the world has grown rapidly.
Geothermal in Vermont
Here in Vermont, geothermal heating is relatively new, and the local geology can make it challenging to install loops of tubing in the ground. But with an appropriately sited water well, the same efficiencies and energy savings apply — very promising when balanced against the high heating costs incurred by our long, cold winters.
NEGPA has not yet developed any of it’s own standard practices
documents. However, we put together an overview of New England and
New York standards and posted as Power Point and .pdf documents on the
“Standards and Regulations” section of the following web page: http://negpa.org.
The Massachusetts DEP has created a comprehensive document, Guidelines for Ground Source Heat Pump Wells, available here: www.mass.gov.
Learn More About Geothermal
- Download REV’s Geothermal Educational Factsheet (pdf)
- Union of Concerned Scientists page on Geothermal Energy
- Download Northeastern Vermont Development Association’s Geothermal Heat Pumps Guide
- Northeast Geothermal
- US Department of Energy, Energy Efficiency and Renewable Energy
- International Ground Source Heat Pump Association (IGSHPA)
- I’ve heard there are several types of Geothermal Heat Pump systems. Which one is right for me?
- How can I calculate the cost of the system, and my energy savings?
- Are geothermal systems hard to maintain?
- What about comfort?
- What are the environmental benefits of geothermal systems?
- Where can I find a geothermal installer?
Most installations use open-loop systems, in which groundwater is pumped from a drilled well through a heat pump, which transfers heat into the building, and then most of the water is pumped back to the well. Closed-loop systems circulate a heat-transfer fluid through coils of buried tubing to move heat either to or from the ground.
Choosing a system appropriate for the physical characteristics of your property requires the design expertise of a GHP contractor, along with the advice of an unbiased energy professional. Efficiencyvermont.com
Follow these Department of Energy links to learn more about the different geothermal heat pump systems, the benefits of geothermal heat pump systems, and the types of site conditions each is suited for.
GHPs save money, both in operating costs and maintenance costs. Investments can be recouped in as little as three years. There is a positive cash flow because the energy savings usually exceeds payment on the system.
The initial investment for a GHP system is greater than that of a conventional heating or cooling system. However, when you consider the operating costs of a geothermal heating, cooling, and water heating system, energy savings quickly offset the initial difference in purchase price.
Cost to install a geothermal heat pump system depends on the heat loss of the building. You can estimate that most installations in new homes will be 10-15 percent more than an equivalent heating/cooling system. This does not include the added costs for the outside work. Many utilities in the Northeast offer incentives to offset the costs to install geo. Look under your utilities Energy Star Home programs to see what is available. northeastgeo.com
A well-constructed 2,000 square foot home may typically require a four-ton geothermal heat pump system. Homes constructed to the Federal “Energy Star” ratings will usually require a smaller heat pump. A typical price range to purchase and install a geothermal heat pump system is widely variable. A standard water-to-air heat pump with ductwork may be in the $3,800 to $5,000 per ton range for the “inside” geothermal equipment, about the same cost as a fossil fuel based heating and air conditioning system. This range varies because of construction variables, e.g. ductwork, plumbing and electrical requirements. Duct and well costs may be the largest variables. Duct costs can vary by as much as +/- $1,000 per ton. If a domestic well is planned for the home, the differential cost for geo maybe small. If employing a “closed loop” earth coupling (not a well) or a dedicated geo well, the costs could be another $1,500 to $2,000 per ton. The “outside” (wells or closed loops) portion of the system is the usual higher geothermal cost factor. Other variables, such as homeowner’s aesthetics and unique comfort requirements can affect the installed costs. A typical heating and central cooling system can be budgeted, per standard costing guideline, at 6 ½ to 8 percent of the value of the home. A more costly, but maximum comfort, radiant floor system with summer fan coils driven by water-to-water geothermal heat pump has been termed “a comfort marriage made in heaven.” This type system can be in the $6,000 – $8,000 per ton or higher range. The numbers of individual zones drive the costs higher. www.igshpa.okstate.edu
Because GHP systems have relatively few moving parts, and because those parts are sheltered inside a building, they are durable and highly reliable. The underground piping often carries warranties of 25–50 years, and the heat pumps often last 20 years or more. Since they usually have no outdoor compressors, GHPs are not susceptible to vandalism. On the other hand, the components in the living space are easily accessible, which increases the convenience factor and helps ensure that the upkeep is done on a timely basis.
Because they have no outside condensing units like air conditioners, there’s no concern about noise outside the home. A two-speed GHP system is so quiet inside a house that users do not know it is operating: there are no telltale blasts of cold or hot air. www.energysavers.gov
GHP systems are safe and protected. With no exposed equipment outdoors, children or pets cannot injure themselves or damage exterior units. GHPs have no open flame, flammable fuel or potentially dangerous fuel storage tanks. www.igshpa.okstate.edu
A GHP system moves warm air (90-105(F) throughout your home or business via standard ductwork. An even comfort level is created because the warm air is moved in slightly higher volumes and saturates the building with warmth more evenly. This helps even out hot or cold spots and eliminates the cold air blasts common with fossil fuel furnaces. www.igshpa.okstate.edu
Currently installed systems are making a huge difference in our environment! The systems are eliminating more than three million tons of carbon dioxide and are equivalent of taking 650,000 automobiles off the road. GHP systems conserve energy and, because they move heat that already exists rather than burning something to create heat, they reduce the amount of toxic emissions in the atmosphere. They use renewable energy from the sun, and because the system doesn’t rely on outside air, it keeps the air inside of buildings cleaner and free from pollens, outdoor pollutants, mold spores, and other allergens. www.energysavers.gov
The International Ground Source Heat Pump Association trains and accredits installers and designers. See their directory here.