Editor's note: This story ran in the July 2007 issue of Lake Norman Magazine.
It’s there – a treasure trove beneath our feet. And for those lucky enough to live on the lake, the treasure also lies underwater, just off the dock.
We’re talking about free, environmentally friendly energy, collected every day by the greatest solar collection systems ever created: the lake water you fish and boat on and the earth around your home. It’s constantly available, ever-renewing power that geothermal heating and cooling systems can tap into.
Large homes can go greenBuilder Willis Spivey, owner of Spivey Construction, recently finished a large new healthy house in Mooresville with special insulation and air handling, plus geothermal heating and cooling for motocross and NASCAR star Joe Nemechek and his wife, Andrea. They have long been interested in environmentally friendly homes.The highlight is a great room that opens to a spacious, covered patio with double-sided fireplace, radiant heat floors and full kitchen overlooking a curving, free-form pool and spa. Beyond the pool, the view to the lake is unbroken because the heating and cooling system is beneath the water.The main floor owners’ suite has awesome lake views and floors heated by the geothermal system, plus a walk-in closet off the bath that is the size of a living room. The bath itself has an enormous walk-in shower and elegant tub, surrounded by what seems like miles of tile that’s soothingly warm on bare toes. A second floor has a kids’ playroom the size of most people’s garages. There’s even a basement with a sunken basketball court and incredible spaces for recreation, media and guest rooms.There are no HVAC units hulking outside the house. There’s still a compressor, but because it gets its warmth and cooling from underground water lines and not the outside air, it sits inside, in a mechanical room, where it is also sheltered from wear and tear. There’s also an air handler, with both geothermal and air-to-air heat pumps. Spivey estimates the Nemecheks spent 25 percent more on the equipment and installation than they would have on a traditional HVAC system. But they started realizing an estimated 50 percent savings in their electric bill “the moment the unit was turned on,” as Spivey likes to say. There are also several tax credits for which they qualify.
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Pay more, save laterOnce installed, geothermal heating and cooling can save owners 50 to 60 percent on heating, cooling and hot water, according to the Environmental Protection Agency. It’s one of the reasons the federal government gives tax credits for switching to geothermal, or installing it in new construction.The system doesn’t run on fossil fuel, so owners aren’t affected by fluctuating prices. The newest models offer dual-capacity compressors and variable speed blowers to provide precise temperature control inside. Outside, loops filled with an anti-freeze fluid are sunk into the ground or water to collect Mother Nature’s cache of trapped energy, so most of the system is invisible. The rest of the mechanicals are indoors, so they also require less-frequent maintenance.“Yes, it costs more to install, but the minute you turn on the system, there’s a savings,” says Brian Cash, one of the family owners of SHA Mechanical, the Troutman contracting company that installed the Nemecheks’ system. The company has been installing geothermal heating and cooling for a couple of decades. “Water is even more efficient at transferring heat, so if you live on the lake, installation is usually less than if we sink the system in the earth. That’s because fewer loops are required,” says Cash, who also owns Environmental Solutions of the Carolinas, a spin-off company that deals with mold remediation and other environmental issues. He stresses that, unlike some geothermal loop systems, the market, the ones they sink into the lake here are closed systems that don’t pollute or mix with the lake water in any way.The EPA recognizes geothermal as the most efficient heating source, says Spivey, who adds that he delights in installing environmentally friendly and healthy house systems. It doesn’t have to be new construction, either. “We’re actually going into historical homes and upgrading them to geothermal heating and cooling,” he says.“It’s really a case of pay me now or pay me later,” Spivey says. “The bigger the house, the more savings you realize. For example, let’s say the normal power bill for a 12,000-square-foot house is $800 a month. You could expect that it would be half that with a geothermal system.” “In addition,” he says, “geothermal systems are known for delivering a consistent, even flow of conditioned air throughout the house, eliminating those cold spots that people sometimes complain about with traditional HVAC.”
Simple physicsThe geothermal concept is simple: Just a few feet underground or about 8 feet into the lake, temperatures stay relatively constant year round – they don’t fluctuate the way air temperatures do. Because it’s warmer underwater (or underground) than in the air in winter, the antifreeze fluid in the loops quickly takes on that warmth. Geothermal piping transfers the warm fluid to the house. In summer, the situation reverses, and the loops’ location underwater or underground acts as a heat sink, pulling heat from the house. A by-product is free hot water in the summertime. Once the fluid-filled loops are buried or sunk into the lake, they’re invisible. “We sink the loops in a 25-foot hole in the lake,” Spivey says. “Then the only requirement is that there needs to be 8 feet of water on top of the loops at all times.”The geothermal piping that leads back to the house also is buried, and in a month or two, you won’t know anything is there.Spivey and Cash say they would like to educate people building or renovating houses of any size about the option of geothermal. Cash says his biggest gripe with local builders is that “they don’t give people a choice of HVAC systems, probably because they don’t know there is a choice.”