As fuel prices continue to rise, many homeowners are looking for new, more energy-efficient means of cooling their homes. Only a few feet down in the ground, the temperature remains relatively constant at around 50 to 59ºF, ideal for underground cooling systems.

Unlike conventional heating systems ground-source systems, don’t burn fossil fuels to produce cooling. Instead, they use the supply of natural thermal energy located just below the earth’s surface.

The most common systems are all closed-loop, meaning there is no direct interaction between the heat exchange liquid and the earth; heat-exchange takes place through the piping. The major differences between the types of closed loop systems involve how their piping is installed. Today we use high-density polyethylene pipes.

The closed loop system is usually more effective than the open system since it cools and recools the same air. Air from inside the home is blown through the underground of tube where it is moderated to near earth temperature before returning to be distributed via ductwork throughout the home or structure. Larger diameter tubes need less total length.

The open loop system - outside air is drawn from a screened intake in the yard through, typically 100 feet or more of straight tube into the home.

Horizontal Installation - Where sufficient land is available, piping is buried horizontally, parallel to the home. Typically, two pipes are buried at four feet and six feet underground.

Alternatively, both pipes may be buried together at five feet and coiled in The Slinky approach. Once the loop is in position it is very difficult to modify but a well designed and installed loop should never fail.

Vertical Installation - If land is limited or landscaping and vegetation must be protected; vertical installation may be a better choice. Instead of running piping in a horizontal underground trench, it is inserted into four-inch vertical holes, drilled 100 to 400 feet deep.

Energy experts say that homeowners who purchase a system can recoup their initial investment in 3 to 5 years, depending on the local cost of electricity. However, many states and municipalities offer tax incentives, which can greatly speed the rate of return.