In an area that often experiences temperature extremes, from bone-chilling winters to heat-stroking summers, homeowners are faced every month with a reminder of just how much it costs to keep their indoor environments comfortable. The price of heating and cooling seem to be on an ever-increasing trajectory, and the expense of oil is in an almost constant, upward spiral. Taking the time now to invest in alternative energy sources may be the best way to prevent heating and cooling bills from taking an even bigger bite out of the household budget, whether you’re planning new construction or renovating an existing home. But what are the options? And where should you begin? Relax! Look no further than the ground beneath your feet.
Many of us have heard of geothermal heating and cooling, but may not have a clear idea of how it works, and how it can be used to provide for a home’s energy needs. Basically, ground source heat pumps, or GSHPs, use electricity to extract heat from below the earth’s surface and transfer it into a home. And in the summer, when outside temperatures rise, heat is transferred from inside, back into the ground. Why does this work? Heat moves much more efficiently through the ground than through the air, and 10 feet below the earth’s surface, temperatures are a fairly consistent 55 degrees. Once tapped, this storehouse can be used to heat a house in the winter, or cool it down in the summer. As an added bonus, the heat generated in the exchange process can be used to heat domestic hot water.
But how, exactly, does this system operate? First, a little technical information. There are two types of GSHPs, a Closed Loop system and an Open Loop system. The Closed Loop system is composed of loops of plastic pipe buried at depths of six feet and greater. In this system, the heat pump continuously moves the water and a transfer fluid (such as antifreeze) through the pipes. An Open Loop system, on the other hand, uses an existing well, pond, or other source, for the water required for heat exchange. The water is pumped in from the source, provides heat exchange, and then is returned to the intake source. Hence the name “Open Loop.” If a pond is the source, says John Wright, of Hudson Valley Clean Energy, a solar electric and geothermal installer, it must be a minimum of a half-acre in size and maintain a depth of eight feet all year round.
So, where do all these loops go? Well, there are two different methods of installing them, either vertically or horizontally. If you have limited land space, placing the loops vertically may be the only option. However, drilling to the necessary depths, often of 200 feet or more, can get expensive. Larger areas are best covered with horizontal loops placed in trenches, but this area’s rocky soil can make this option less than ideal. The best way to determine which system is appropriate for your home is to speak with the installation experts and schedule an in-person site assessment of the home and property.
Once the pipes enter the house, they carry the water to the geothermal heat pump.
This is generally installed in the basement or in a utility closet, and is just a bit louder than a refrigerator. If noise is a concern, however, the closet can always be soundproofed. In addition to the outside loops and the geothermal heat pump, there are two other important elements of a GSHP. All that warm and cool air has to travel through your house somehow, right? The most popular, and least expensive option, says Wright, is simply ductwork. And lastly, in order to ensure proper ventilation, an HRV, or Heat Recovery Ventilator, is used to preserve indoor air quality and dehumidify the air.
But don’t think that a GSHP can only be considered before your home is designed or built. Charles Lazin, President of Altren Alternative Energy, estimates that while sixty percent of the company’s installations are in new construction, forty percent are retrofits in existing homes. Since many existing homes are already outfitted with ductwork, this can simplify the process further, and work towards reducing the overall cost. In fact, the system can be considered at any phase, Lazin says, whether the architects are in the process of planning and designing the home or the general contractors are in middle of construction.
But in an ideal situation, says Wright, the best time to consider a GSHP is during the planning stages of a new home. Not only because it’s easier to start from the ground up, but also because the entire home can be constructed in the most energy-efficient manner possible. In well-sealed homes, more of that environmentally friendly warm or cool air will be kept where you want it: inside.