Geothermal Heating

Geothermal energy reduces heating and cooling costs sustainably

If you've been reading the news and pondering heating and air conditioning costs, you know that energy costs are likely to climb substantially in the future. Our petrochemical dependent methods of supplying our homes with heat, lighting, and hot water are going to be compromised as supplies of these non-renewable resources diminish. Considering that more than half the cost of energy used in your home is used for heating and cooling, it's worth considering the options.

Rather than fear a loss of energy sources, now is the perfect time to investigate methods of sustainably producing power and heat. Capture the earth's natural heat to warm and cool your home by using a geothermal heat pump, which uses half the energy of a standard heat pump. Also referred to as GeoExchange, earth-coupled, ground-source, or water-source heat pumps, they work particularly well in more extreme climates where standard heat pumps are not be suitable. Geothermal heat pump (GHP) systems have other advantages. They are

What's not to love? Geothermal systems condition air and may reduce indoor humidity. That can be a huge advantage in humid or damp regions where the war again mold and mildew is a common occurrence. They are supremely flexible, too, and can be installed as new or retrofit systems.

What's a geothermal heat pump and how do they work?

Basically, ordinary heat pumps use air as their source and move heat from a cooler location to a warmer location, effectively making a warm space warmer and a cool space cooler. It makes your home warmer in winter and cooler in the summer, and do it so efficiently that it provides as much as four times the energy it uses.

Geothermal heat pumps are similar in principle, but use even less energy. Using a ground heat exchanger instead of air, the GHP uses the stable temperature stored in the ground to increase temperatures in the winter and reduce them in the summer. Depending on where you live, a few feet below the dandelions in your garden, the earth's temperature is a stable 45–75 degrees fahrenheit. The energy costs are truly minimal.

System types

The heat exchanger is only half the story. To pull the heat or coolness from the earth, a high-density polyethylene pipe system carries fluid from the heat exchanger through the ground and back again. There are two basic types of systems, closed and open loop. The open loop system used ground water; the closed loop uses an environmentally safe anti-freeze/water mixture.

Closed loop systems run from the heat exchanger through a vertical or horizontal tubing arrangement depending on the amount of land available. According to the US Department of Energy, the horizontal is the more cost effective of the two methods for residential applications. Vertical systems are often used for larger buildings because the cost of land to support a horizontal system would be too expensive. A third type of closed loop system using a pond or lake is cost effective, but most of us don't have lakeside property or acreage to create our personal pond.

An open loop system is another residential, albeit more expensive, alternative that uses well water as the heat exchange fluid. Water is pulled from one well through the system to the heat exchanger then returned to a second recharge well. Such a system is restricted by the availability of relatively clean water as well as meeting all local codes and regulations. This could be a viable approach especially if a homeowner already has one well dug.

For a visual reference, see the excellent description provided by the US Government Department of Energy .

So what's the catch?

As of now, GHP systems are relatively expensive to install and can cost up to three times the cost of an air-source heat pump system with air conditioning. A variety of factors including lot size, subsoil, and landscape all come into play and determine the viability of a geothermal system installation as well as its cost.

However, some of the costs can be mitigated by low-interest home improvement loans, government-sponsored incentive programs, energy rebates, and tax deductions. If you are rolling the cost into a mortgage or refinance, the cost vs. the immediate savings can begin accruing immediately. The Department of Energy estimates that the installation cost on a retrofit can be recouped in two to ten years. By checking all possible sources for financing and rebates, you could reduce the cost of a GHP system substantially.

Determining the suitability of system type depends on your soil character and local geology, whether the building is new construction or a retrofit, existing water sources and aquifers, and how much land is available.

This type of system is outside the range of knowledge and equipment for almost all homeowners to do themselves, so the only practical approach is to hire qualified contractors for the installation. Sources to check for qualified specialists include the International Ground Source Heat Pump Association and the Geothermal Heat Pump Consortium.

Resources


If you have heating and cooling system installation, repair, or service on your list of home improvement projects, a pro at UpdateRenovate can help.

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