Wouldn’t you want to be in a home where the temperature always feels comfortable but you don’t see the system anywhere? That is a system that efficiently works with even less maintenance. And that system is what’s referred to as geothermal heating and cooling. A geothermal HVAC (heating, ventilation, and air conditioning) brings your home in harmony with the earth and takes advantage of the subterranean temperatures so it can provide cooling during summer and heating during winter.
How does this system work?
While outdoor temperatures fluctuate, the underground temperature doesn’t change as dramatically. The temperature 4 to 6 feet below the ground remains fairly constant all year round. A geothermal system that consists of buried pipes (earth loop), indoor handling unit, and/or a pump, will capitalize on these temperatures to provide you free energy.
Do not confuse a geothermal HVAC with geothermal energy as the process differs.
The pipes in the earth loop are normally made of polyethylene. Depending on the site’s characteristics, these pipes can be buried vertically or horizontally. If there’s an available aquifer, engineers may drill a well into the underground water which is referred to as an open loop system. The water will be pumped up, will run past the heat exchanger, and, through reinjection, will be returned to that same aquifer.
During winter, the stored heat underground will be absorbed by the fluid that circulates through the well or the earth loop. The heat will be compressed by the indoor unit to a higher temperature and will then be distributed throughout the building, like it’s an air conditioner that runs in reverse.
During summer, the heat from the building will be pulled by the geothermal HVAC and will then be carried through the earth loop or the pump to reinjection well, and will be deposited into the cooler aquifer/earth.
Geothermal HVAC systems, unlike the ordinary HVACs, do not generate heat by burning fossil fuel. They simply transfer the heat to the earth and from the earth. Electric power is only used to operate the compressor, the pump and the unit’s fan.
The three main components of a geothermal system is the liquid heat-exchange (closed or open loop), the air-delivery system (or ductwork) and/or radiant heating (which is in the floor or elsewhere), and the heat-pump unit.
The efficiency of a geothermal heat pump is based on their COP or coefficient of performance. It’s a way to determine the amount of energy the system moves over the amount of energy it uses. Generally, geothermal system have a COP of 3.0 to 5.0 which means that 3 to 5 units are being supplied as heat for every unit of energy that is used to power the system.
Maintenance for geothermal units is very little. If installed properly, the loop that’s buried can last for generation. The compressor, pump, and fan are protected from harsh weather conditioner as they are housed indoors. This means that these parts can last for decades. The only required maintenance is a regular changing of the filter and annual cleaning of the coil
The geothermal systems have been around U.S. and beyond for more than 60 years. They do not emit any greenhouse gases as they are working with nature.
Eco-friendly homes have geothermal HVAC systems as a common feature. Last year, 20 percent of U.S.’ newly built homes account for green projects. According to the predictions of an article in Wall Street Journal, green housing will skyrocket to $114 billion from $36 billion. Of the entire market of housing, that is approaching 30 – 40 percent.
However, many information on geothermal HVAC are based on information that are outdated. Here are some of the common myths about geothermal HVAC:
Because it uses electricity, geothermal HVAC systems aren’t considered renewable technology.
Truth: to move up to 5 units of heating and cooling from the earth to the building, a geothermal HVAC system only uses one unit.
Wind power and photovoltaic are more favored as renewable technology than geothermal HVAC system.
Truth: from the electrical grid, a geothermal HVAC system can take away 4 times more kilowatt hours of consumption than wind power and photovoltaic. In reducing environmental impact, the geothermal HVAC system is the most cost effective.
Having a geothermal HVAC system requires lots of yard for the polyethylene piping earth loops.
Truth: the loop can be buried vertically depending on the site’s characteristics. And if an aquifer is available, there will only be a need for a few square feet.
Geothermal HVAC systems create too much noise.
Truth: the system runs quietly and there’s no outdoor equipment that can bother neighbors.
Geothermal systems will eventually wear out.
Truth: the earth loop can last for generation while the heat exchanger can last for decades. However, should there be a need to replace the heat exchanger, the expense will be much less than having a new geothermal system put. There is even a new technical guideline that eliminates the issue of thermal retention.
Geothermal systems only function in heating mode.
Truth: they function in cooling just as effectively. They can also be engineered to have no additional heat source. Although, customers may find it more cost effective to have a backup system for the coldest days if it means that their loop can be smaller.
A geothermal HVAC system can’t heat a home, a pool, and water simultaneously.
Truth: it can handle multiple loads at the same time.
Geothermal HVAC systems have refrigerant lines in the ground.
Truth: most systems only use water in the lines or the loops.
Geothermal systems use a lot of water.
Truth: it doesn’t consume water. If an aquifer is being used, all the water returns to the aquifer.
Without local and federal tax incentives, geothermal HVAC technology isn’t financially feasible.
Truth: with the federal and local incentives amounting to 30 and 60 percent of the total geothermal system cost, it can make the system’s initial price competitive with conventional equipment. During construction, a standard air-source HVAC can cost around $3,000 for every ton of cooling and heating capacity. A geothermal HVAC system cost about $5,000 a ton, and can even go $8,000 to $9,000 a ton. However, the new installation practices are lessening the costs, in which the cost is getting closer to the conventional systems.
The facts about the geothermal HVAC systems are the same facts that confirm the efficiency of these systems.