How Much Can I Really Save?
Geothermal heat pumps, or ground source heat pumps (GSHP) have been around for more than half a century. The technology exploits the constant temperatures we find right below the Earth’s surface, either for heating or cooling purposes, and has significantly higher efficiency than electrical heating, furnaces or even air source heat pumps.
Geothermal heat pumps will obviously do well when it comes to lowering your carbon footprint, but can you really save money with them?
Costs of a Geothermal Heating and Cooling System
The installation of a geothermal heating and cooling system is significantly more complex and expensive than the installation of an air source heating system. It involves drilling, digging and laying pipes, all of which are expensive and time consuming. On the other hand, the benefits are greater.
The financial viability of a geothermal heating and cooling system (of which geothermal heat pumps are an intrinsic part of) is dependent on many different variables:
New construction or retrofitted for an existing building?
This is the first thing you should consider. A geothermal heating and cooling system is less affordable if it has to be retrofitted for an existing building, especially in the case of in-floor (or sub-floor) radiant heating. A geothermal retrofit is sometimes not financially feasible. However, the environmental benefits still apply!
What is the type and size of your geothermal heating and cooling system?
Geothermal heat pumps can be used essentially everywhere. However, what system type you can install at a certain location depends on hydrological, geological, spatial characteristics of the land, and finally, how much space you have available.
How much of your energy consumption should be covered by the geothermal heating and cooling system? Do you have enough space available to install a system big enough to provide you with your desired power output? Bear in mind that covering as much of your energy demand as possible might not be the best option from a financial standpoint.
Are you eligible for any financing programs?
Make sure that you figure out what kind of incentives/rebates/grants from the federal, state, and local governments that you are eligible for. The Database of State Incentives for Renewable Energy (DSIRE) should be able to provide you with more information on this.
Also note that you possibly can finance a geothermal heat pump (and the rest of the system) through energy-efficient mortgages. Check with banks a mortgage companies to find out more about this. Also call up your electrical utility company and ask if they offer any financing for people installing geothermal heating and cooling systems.
How high efficiency rates are you able to get?
One of the key aspects of geothermal heat pumps is that they use the temperatures below the Earth’s surface, and not the outside ambient air, which is what air source heat pumps use. The below-surface temperatures are significantly more stable than those above – even throughout the different seasons of the year. The Earth acts as a massive energy storage (or an insulator), and the temperatures a few feet below the surface is not noticeable affected by outside ambient temperatures dropping. The temperature range is 45°F – 75°F (7°C – 24°C), depending on latitude angle.
Efficiencies between 300%-600% on cold winter nights are not uncommon. This looks especially good when compared to 175%-250%, efficiency rates for air-source heat pumps during cold outside temperatures. The bottom line is that temperature differences play a major role in the efficiency of heat pumps and is an intrinsic part of estimating efficiencies.
There are different financial models depending on how you use your geothermal heating and cooling system. Typical applications include:
- A desuperheater comes as a part of geothermal heat pumps. These can be used to provide hot water for a swimming pool, showers or whatever else you can think of. Overall energy demand in a building goes can go down significantly if a part of the hot water is supplied by a geothermal heat pump.
- Then there is in-floor (or subfloor) radiant heating. Hot water circulates through a series of pipes that has been laid beneath the floor.
- Geothermal heat pumps can be used to control humidity. This makes efficiency goes up if you are located in a humid area, and would rely on other means to control humidity if it weren’t for a geothermal heat pump
- Maybe you want to use your geothermal heat pump for your garage, basement, for snow and ice melting in your driveway, or in your greenhouse.
What is the payback time of a geothermal heating and cooling system? Let’s look at a few typical numbers:
When we are estimating the initial costs of a geothermal heating and cooling system we have to take the system type, size, labor costs and drilling conditions into account. The ground loop of the system (the part of the system that sits below the surface) is usually the most expensive. The rates are usually somewhere between $1,000 and $3,000 per installed ton for the ground loop alone.
The total costs of a geothermal heating and cooling systems for home and small-scale commercial use usually ends up somewhere in the range $10,000 -$25,000.
As you can see, costs are significantly higher than those of air source heat pump systems. In fact, the initial costs of a air source equivalent of a 3-ton geothermal heat pump system, would be between $4,000 and $11,000 cheaper.
This is where it gets interesting. While the initial costs of a geothermal heating and cooling system are much higher than air source heat pumps, furnaces, or electric resistance heating for that matter, the efficiency rates are generally much higher.
The warranty of the underground piping can be as high as 50 years, while the heat pump usually has a warrant of around 25 years. These systems are extremely reliable and do seldom need repairs.
High efficiency rates combined with low operating and maintenance costs, annual energy savings is typically between 30% and 60%. Numbers from US Environmental Protection Agency (EPA) show that homeowners save 30-70% on heating and 20-50% on cooling costs by using geothermal heat pumps compared to other conventional systems. This translates to roughly $400 to $1,500 annual savings.
After a certain amount you hit a threshold where saved up money equals costs. This is known as the payback time and is usually somewhere between 5 to 7 years. Compare this to the warranty of a geothermal heating and cooling system, and investing in geothermal for your house or business becomes a no-brainer. Not to mention the obvious environmental benefits that comes with an installation like this.