Geothermal Heating Pros and Cons: Is it Right for Your Home?
Geothermal heat pumps (GHPs), which provide both heating and air conditioning in your home, and also can heat your water — sometimes for free — have become increasingly popular in recent years.
These HVAC appliances are amazingly efficient and “green” compared to traditional options, as they harness the nearly constant temperatures under the ground to keep your home comfortable in every season. Geothermal heating systems deliver serious energy savings over time, too.
However, there are drawbacks and many things to consider as you look to install a GHP. The truth is, geothermal systems are not going to be right for every home or every homeowner despite their many advantages. Your priorities, your budget, and your home’s physical location will ultimately help you make the best decision about what type of HVAC system is right for you, whether it’s geothermal or more conventionally powered/fueled.
If you’re in the market for a new HVAC system because you’re building a new home or looking at replacement options for your existing heat pump, boiler, or furnace, you may have just been introduced to geothermal heating and cooling for the first time. You may already know that these high-efficiency systems use the constant temperature of the earth as the heat exchange medium instead of the outside air temperature, which requires at least some excavation or drilling to install the exchange “loops” below ground.
In short, geothermal heating and cooling works, and uses 25%-50% less energy to produce comfortable indoor air compared to conventional HVAC systems, because it doesn’t have to contend with drastic seasonal swings in air temperature outdoors for heat exchange.
For example, even in locations with extremely cold winters, the earth’s temperature just below the surface will never drop under about 45 degrees Fahrenheit. That means the fluid flowing through the exchange loops is never exposed to, say, frigid 2-degree temperatures, even if that’s how cold it is outside your door. GHPs simply don’t have to work as hard as conventional heat pumps to keep your home’s interior comfortable.
As mentioned above, GHPs require access to the earth at a depth where the temperature does not fluctuate wildly compared to air temperatures above ground. This is accomplished by installing what are known as loops, which can be configured in a few different ways in either “open” or “closed” formats.
According to the United States Department of Energy’s informational resource website on geothermal heat pumps (also linked above), there are currently four common types of loop options for residential and commercial geothermal heating systems (three closed and one open format), though other configurations also exist. Geothermal heating and cooling technology has been advancing rapidly in recent decades for wider adoption, so loop and other setup options will continue to evolve.
These systems utilize an antifreeze solution, water, and/or refrigerant (generally R-410A) circulating through copper and/or plastic tubing, which is buried below ground and may potentially run beneath a body of water. It may go without saying that the fluid within the loop is kept carefully contained – or closed off — from the ground around it and is never discharged into the earth.
Four common types of closed loop configurations are:
Note that vertical, horizontal, and diagonal loops are used with what’s known as Direct Exchange (DX) technology, which doesn’t require the use of water wells, water sources, or secondary loops that so-called water-source technology does. (Water-source geothermal heat pumps were developed for larger-scale industrial applications, so they’re not something most home and small commercial clients would be considering.)
In open loop systems, there is a discharge of the heat exchange fluid – in this case, relatively clean water instead of antifreeze or refrigerant – with the surrounding environment. Open loop systems can only be installed at sites with an adequate water supply and where rules about groundwater discharge allow.
There are many positives to installing geothermal heating and cooling systems in your home or commercial building, and these certainly outweigh the negatives for many people, which mainly have to do with high installation costs. If you’re concerned about reducing your individual environmental footprint and not having to worry about fluctuating gas and oil prices affecting your heating and cooling budget, geothermal may just be right for you.
Because GHPs use much less electricity than conventional HVAC systems, as we mentioned above, and don’t rely on natural gas or heating oil either, these systems are not a significant source of pollution. Your geothermal system will reduce emissions as it drastically cuts your home’s energy usage, and that’s definitely environmentally friendly!
Geothermal equipment also lasts for a long time, with underground loops often warrantied for 25-50 years. The heat pumps themselves are usually guaranteed to last about 20 years. Compare that to the average lifespan of 15 years for a typical home air conditioning unit or heat pump, and you will see that less frequent equipment replacement is much better for the world (and your wallet, too).
As you’re shopping for geothermal heat pumps, you might raise your eyebrows a few times at the prices you’re quoted (typically between $10,000 and $20,000, including installation). Much of the high upfront cost has to do with installing the ground loops. This system does feature equipment with fewer moving mechanical parts than a traditional system, though, which is why it lasts so much longer.
The good news about the more substantial initial investment needed for GHP-based systems is that they will generally pay for themselves with energy cost savings in about 2-10 years, according to energy industry sources. There may also be special green energy incentives available from federal, state, and even certain local government entities and power providers to shave some dollars off that high initial price tag for the system. And, depending on your system’s setup and capabilities, you will be able to reap the reward of free hot water as a by-product of system operations!
If you are able to roll the cost of the new GHP into your mortgage for a new home, your savings will be even greater. The system’s price will not actually add that much extra to your monthly mortgage payment, and the energy cost savings you realize will easily exceed that amount throughout each year.
Speaking of adding a GHP to the plans for your new home, it’s true that geothermal systems are easier (and possibly less expensive, depending on things like soil condition and geology at your new home site) to build from the ground up with a new home than they are for retrofits in most existing homes. Why?
It’s true that many residential GHPs utilize closed-loop systems for heat exchange, and this has to do with the flexibility offered by the different configurations, as well as cost-effectiveness. For instance, diagonal systems typically have a small footprint and are appropriate for smaller home lots. Horizontal installations need more space to dig trenches for the loops, but can accommodate more difficult-to-excavate geology.
For individuals who are concerned about the use of antifreeze fluids or refrigerants, open loop systems use only water as a heat exchange fluid. This water is drawn from the earth and returns to the earth once the system has used it.
As we discussed previously, one of the major drawbacks of geothermal heating systems is high installation costs, especially for certain retrofit or heat pump replacement projects. Additionally, electricity is still required to operate GHPs, so while this HVAC equipment is more sustainable than conventional, air-source heat pumps, it’s not completely eco-friendly (especially if you live in an area where your electricity is produced by coal-fired plants or other non-renewable sources).
A significant concern of geothermal systems, especially in regions like ours here in Central Pennsylvania where there are a lot of forests and even some seismic shifting (aka earthquakes), is damage to the underground loops. Especially in closed loop systems where refrigerant is used as a heat exchange fluid, a break in underground piping can lead to soil and groundwater contamination and is also costly to repair.
As mentioned above, damage to closed loops can be disastrous, and it’s always a risk, as tree roots or burrowing animals can cause pipe breakage and fluid leaks. Open loop systems are a bit less risky this way, as they utilize only water, but they are less commonly installed because site requirements are so specific. There is also the possibility that well pumps needed to circulate the water in these systems could discharge pollutants like sulfur dioxide.
Adding a new geothermal HVAC system to your existing home may not be impossible, but sometimes higher costs for installation are a reality in retrofit projects. Adding ductwork to your home or having to complete land engineering work to know where refrigerant loops can be installed without disturbing current structures, underground utilities, or mature landscaping like large shade trees can drive up total pricing.
Depending upon your priorities, geothermal could be an excellent option for your new home or commercial building. In addition to the advantages of GHPs that we already discussed, these systems can be scaled to heat and cool virtually any size building efficiently.
Ready to talk geothermal heat pumps for your new or existing home or commercial property? Ressler & Mateer has the specialized technical knowledge required to install these systems the right way. Not many of our competitors can claim to be so qualified. Give us a call today to discuss your new or retrofit project goals.
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