What to know before you go geothermal

What to know before you go geothermal

Digging deep into geothermal systems

Geothermal systems can produce sticker shock, but the greatly reduced electrical bills — and the 30 percent federal tax credit — might be worth the initial investment.

Do you want to take advantage of the savings available when you install the leading heating and cooling system in your home? Geothermal heating and cooling systems give you access to a clean, renewable, free source of energy that can reach efficiency ratings as high as 600 percent during the coldest nights of the year, according to the Department of Energy.

Before you buy, learn the efficiency ratings and other relevant information that will inform your purchase.

Efficiency ratings

Because geothermal heat pumps (GHPs) heat and cool the home, they are assigned two efficiency ratings:

• Coefficient of performance (COP). Simply put, this efficiency rating calculates the heat pump's ability to generate heat compared to the amount of energy it consumes. To make the calculation, manufacturers test the amount of British thermal units (BTUs) of heat that the unit delivers into the ground and then compare that number to the total number of BTUs of electricity used during the process.

• Energy efficiency ratio (EER). Measuring cooling output, the EER calculates a system's performance in terms of how the capacity it generates compared to electricity consumed. In general, for a system that consumes 1 kilowatt of electricity to generate 10,000 BTUs of cooling (based on a one-hour scale), the EER rating equates to 10. A GHP with an EER of 20 generates 20,000 BTUs of cooling from 1kW of energy.

Energy Star criteria

Purchasing an Energy Star-qualified GHP offers homeowners access to even more savings. Qualified systems must meet federal guidelines for efficiency while offering homeowners access to features that deliver comfort and increase savings potential. Here's an overview of the minimum qualifying efficiency ratings for GHPs of various types:

• Water-to-air pumps must achieve a 14.1 EER and 3.3 COP for closed-loop systems, whereas open-looped systems must rate a 16.2 EER and 3.6 COP.

• Water-to-water systems must achieve a 15.1 EER and 3.0 COP (closed) and 19.1 EER and 3.4 COP (open).

• Direct geoexchange equipment must achieve a 15.0 EER and 3.5 COP.

Energy Star reports that GHPs that qualify for the program run 45 percent more efficiently than a system that's rated standard efficiency.


There's good news and bad news when homeowners opt for installing a GHP. The significant savings in terms of monthly energy costs and operating costs over the system's life span come at a price. As a result, the purchase cost of a geothermal system is high. But, there is an upside from the number of ways you can manage the purchase cost.

The federal government is offering tax incentives for the purchase of renewable, energy-efficient equipment like GHPs. Through December 31, 2016, homeowners who purchase a qualifying GHP can take advantage of a 30 percent tax credit. That credit instantly reduces the cost of purchasing the equipment, so if you purchase a $20,000 GHP, you'll get a $6,000 tax credit on your next return. Many homeowners also opt for rolling the price of a GHP into their mortgage, which often translates to only a small bump up in the monthly payment.

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After contractors installed this geothermal system, this member reported that her electric bills had been cut in half. (Photo courtesy of Angie’s List member Joanne B. of Goochland, Va.)
After contractors installed this geothermal system, this member reported that her electric bills had been cut in half. (Photo courtesy of Angie’s List member Joanne B. of Goochland, Va.)

Get to know eight proven benefits of geothermal heating and cooling systems, and you'll get on the fast track to learning more about these ingenious, renewable energy systems.


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