The Green Home

Put the Earth to work for you: Geothermal systems

Posted March 16, 2012 8:22 p.m. EDT

With the hot summer days approaching fast this year, many homeowners are getting ready to make the switch from winter’s high gas bills to summer’s high electricity bills. Often they don’t realize that the solution to both might be right under their feet.

Geothermal heating and cooling systems are a modern application of an ancient principle. Anthropologists speculate that one of the reasons that our prehistoric ancestors lived in caves was simply that ground-based dwellings were far more temperate than above ground homes. The earth around them maintained a consistent temperature despite the season – cooler in the summer and warmer in the winter than the weather outside.

Today, homeowners use geothermal systems to bring that temperature consistency into their home heating and cooling needs, drastically reducing the use of gas furnaces and electric air conditioners, creating more comfortable homes and reducing energy bills year-round.

How geothermal systems work

Geothermal systems comprise three parts – a ground loop of pipes buried in the soil around the home that extract or return heat to the ground, a heat pump unit in the home that regulates the process, and a distribution system (ie duct work) that carries the air from the heat pump through the house.

In North Carolina, the ground loop system can be either vertically oriented (it goes straight down into the ground) or horizontally oriented (it spreads out under the ground from the side of the home). The configuration of the ground loop system is dependent on the amount of land that the homeowner has available to excavate and install the system.

Benefits of geothermal systems

Geothermal systems are one of the ultimate “green” technologies; a use of passive heating and cooling that has no carbon output or chemical byproducts to affect the environment. For the homeowner, it can also represent a significant savings over traditional forced air furnaces and air conditioners – a 40 to 70% reduction in energy bills. And many homeowners find that the geothermal system is far quieter (in fact, virtually silent), creating a more peaceful home.

Affording a geothermal system

If you’ve always felt a geothermal heating and cooling system was out of range of your budget, an energy efficiency contractor can help you determine the full extent of the incentives you qualify for, and give you an “out of pocket” quote that might surprise you in its affordability.

Given all the benefits of geothermal heating and cooling systems, it’s not surprising that this is one of the areas in which the government and local utilities offer generous incentives for homeowners. For 2012, the federal government offers a 30% tax credit towards the installation of a new geothermal system, with no maximum. In addition, North Carolina offers a tax credit of up to 65% of the cost of a new geothermal system. Local utility vendors like Progress Energy and Duke Energy also offer cash rebates up to $300 towards hardware and installation of geothermal systems.

Additionally, some contractors also offer GEOSmart Financing specifically for new geothermal heating and cooling system. Homeowners can borrow up to $45,000 with no/reduced interest for up to 18-months – an easy way to carry the cost of a new geothermal system until the following year’s tax return.

Best time to install

In our area of North Carolina, virtually any time of year is appropriate to install a geothermal system, however Spring is often selected by homeowners because it’s less disruptive for landscaping and gardening activities that come later in the summer.

About this Blog:

Bobby Ferrel, founder of Green Horizon oversees The Green Home blog. Ferrel is co-founder of Green Horizon, with offices in the Triangle and Charlotte, offering home owners and builders a one-stop shop for energy efficiency and green building. Services include home performance assessments, weatherization, closed crawl spaces, all types of insulation, HVAC and geothermal installation and maintenance. Reach Bobby directly at or visit him online at