Key Points
- Heating and cooling systems quantify energy efficiency using EER (Energy Efficiency Ratio) and COP (Coefficient of Performance), where higher ratings signify better efficiency.
- When comparing geothermal heat pumps to an air-source heat pump equivalent, ground-source systems consistently earn better energy efficiency ratings.
- Factors including climate, soil quality, flora, available land, and access to clean water influence whether a geothermal system is worth the investment.
Earth’s ever-changing climate forces efficiency into the limelight as a key factor in consumers’ decisions about finding a new heating and cooling system for their homes. It’s common knowledge to HVAC professionals and homeowners alike that geothermal heat pumps are significantly more efficient at heating and cooling most homes than air-source heat pumps and other traditional methods. But just how much of a difference does geothermal heat pump efficiency really make? IWAE has the low-down on all things geothermal. Read on to determine whether a ground-source system is right for your home.
How Does a Geothermal Heat Pump Work?
How geothermal heat pumps work shares a fair amount of overlap with traditional, air-source heat pump systems. Both of these systems:
- Have the ability to cool and heat by reversing the flow of refrigerant through the system
- Use an indoor air handling component to circulate air through a room or ductwork
The big differences between air- and ground-source systems are the source they use to determine the starting temperature and where other components are installed:
- Traditional systems have an outdoor condenser that pulls in fresh air from outside, using the temperature of the air as a starting point. This can vary widely by season.
- Geothermal systems have no visible outdoor components, as all loops are subterranean. These systems use the stable temperature underground as a base for both heating and cooling, lowering the amount of energy required to accomplish your ambiance
Do you know how much more efficient a geothermal heat pump system is than a traditional air-source system? The HVAC industry measures efficiency in several ways, making it harder to compare efficiency across models sometimes. Heat pump condensers and full systems are rated using two of the most common efficiency measurements. The cooling performance of a heat pump is measured in EER (Energy Efficiency Ratio), while its heating efficiency is measured in COP (Coefficient of Performance).
You can find a more comprehensive list of efficiency ratings and their meanings in our efficient HVAC buying guide, but let’s get a quick explanation of what COP and EER really mean:
- COP is the ratio of heat output compared to the energy input of a heat pump
- EER is the ratio of cooling output compared to the energy input
Average Geothermal Heat Pump Efficiency Ratings
Now that we’ve covered what these core ratings are, it’s time to get into the nitty-gritty of what ratings ground-source systems achieve. Single-stage geothermal heat pumps will usually have an EER rating of around 17 or 18. 2-stage geothermal heat pumps score higher EER ratings on full loads, with systems like the ClimateMaster Tranquility 30 series hitting full load ratings in the low to mid 20s. These same 2-stage geothermal heat pumps achieve around 30 EER on partial load efficiency ratings. We see a similar trend with the COP of these systems. Many geothermal heat pump units gain a COP of around 5. Tranquility 30 units have ratings dependent on the unit size and type of loops, though the values range from 3.9 to 7.0 for their COP. This kind of performance is already exceptional, but it’s just the tip of the iceberg. Options like GeoCool’s Inverter heat pump units earn ratings around 70 EER for a partial load and between 3.4 and 6.2 in COP.
To compare the efficiencies and specifications of these two geothermal heavy-hitters, check out our ClimateMaster vs GeoCool article.
Average Air-Source Heat Pump Efficiency Ratings
By comparison, air-source heat pumps typically have EER ratings between 10 and 13. Any traditional heat pump earning above a 12 EER rating is considered highly efficient in most circles, and Energy Star certifies as much for split system heat pumps. The COP of most air-source heat pump units hovers just below geothermal equivalents, with an average rating of around 4.
Which Is More Efficient: A Geothermal Heat Pump or an Air-Source Heat Pump?
Looking at these numbers side-by-side, geothermal heat pump systems clearly come out on top. Ground-source heat pumps are more efficient than air-source heat pumps. The explanation behind this fact highlights why moderate ground temperature makes heating and cooling easier. Air-source heat pumps take the ambient air temperatures in summer and winter and have to work with these extremes. This equates to a system that has to work harder and use more energy to create your ideal indoor environment.
Wouldn’t it be nice if the solution were truly that black and white? While it would be great if a statement as straightforward as “geothermal is always the right choice” could be universally true, nothing is quite that simple in practice. There are a range of factors that affect whether or not a ground-source system is right for you. Some climates don’t gain as much from geothermal systems, but that isn’t the only consideration to take into account. Ask yourself:
- Is the soil in my area suitable for underground installation? Do I have too many trees or other plant life that could lead to issues of leaks or breaks in the loops?
- Do I have enough space to accommodate subterranean loops at all? Is there a suitable water source that I can access?
- Am I in a region that would truly benefit from the heating performance of a geothermal system? Are energy costs in my area high enough to offset the mild temperatures?
Get Your Next Heat Pump from IWAE
Choosing a new HVAC system is a lot of pressure. Even once you’ve decided between an air- or ground-source system, finding the right heat pump for your needs is like a tightrope walk. With IWAE as the ringmaster, you don’t have to worry about what happens if you stumble. Our customer service experts are here as a safety net to cushion the fall and guide you to the perfect heating and cooling solution. We’ll even hook you up with information on contractors that will install the new hardware.
