Heat Pump Showdown: Air Source Vs. Ground Source Unveiled

Photo of author

By Debarghya Roy


Are you on the hunt for eco-friendly heating and cooling solutions? If so, air-source heat pumps (ASHPs) and ground-source heat pumps (GSHPs) are excellent options.

Both systems can save energy efficiency while making your home a more comfortable place to live.

air source vs ground source heat pump

Key Takeaways

• Air and ground source heat pumps are eco-friendly heating and cooling solutions powered by electricity to extract energy from the environment.

• Air source heat pumps have lower installation costs than ground sources but tend to be less efficient in colder temperatures.

• Ground sources can provide higher SCOP ratings than air sources due to more excellent insulation through conduction from soil which leads to improved long-term efficiency saving quarterly power bills.

• Atmospheric pollution, the refrigerant type used (e.g., HFCs & CFCs), and noise level when picking either of these systems should all factor into decisions when choosing between ASHP or GSHP systems for best home/commercial setups, ensuring comfort at the optimal cost-saving potential.

Air Source And Ground Source Heat Pumps

Air and ground source heat pumps use electricity to extract energy from the environment and provide climate control but differ in how they transfer that energy.

How Do They Work?

Air source heat pumps:

  • Air source heat pumps contain a refrigerant that absorbs and transfers air warmed by the sun. These systems harness energy from the low-grade warmth in outdoor air and transfer it into your home.They work best when temperatures are above freezing, operating at lower energy efficiency during cold months than ground source systems.

Ground source heat pumps:

  • Ground source heat pumps extract heat from the earth through buried tubing or vertical wells of water, known as a ‘closed loop’ system, or by exchanging steam on an open loop with boreholes deep into underground aquifers.The exchanger collects ground temperature to boost air to desired levels; this is suitable for all climates because warmer temperatures exist much further down than one would find in the soil near the surface. Soil acts as a thermal bank, enabling effective use of natural energy across winter periods, too, maintaining comfort indoors regardless of external weather conditions.

Differences In the Installation of Air source heat pumps (ASHPs) and ground source heat pumps (GSHPs) 

Air Source Heat Pumps (ASHPs)Ground Source Heat Pumps (GSHPs)
Preparation ProcessRequires a site assessment, an indoor unit to be placed against an exterior wall, and piping that carries hot or cold air into the home.Requires soil quality check, available space assessment, professional drilling for boreholes, and underground pipes must be laid which connect the boiler system beneath the surface.
Installation ComplexityRelatively straightforwardIt requires the involvement of multiple specialists (e.g., electricians, plumbers, engineers) and can take several days
Space RequirementsGenerally less; it can be placed against an exterior wall.Requires approximately 60 meters of vertical space for each borehole.
CostTypically ranges from £1,000 to £2,500, depending on size requirementsOften costs upwards of £3,000
Dependence on EnvironmentNot significantly influenced by the type of land surrounding the propertyThe kind of land surrounding the property can significantly impact the feasibility of the installation

Efficiency Of Air Source And Ground Source Heat Pumps

Comparing the energy performance of air source and ground source heat pumps, both models have high-efficiency ratings: Air Source Heat Pumps (ASHPs) are rated by their Energy Efficiency Ratio (EER), while Ground Source Heat Pumps (GSHPs) measure Seasonal Coefficient of Performance (SCOP).

    Efficiency ParameterAir Source Heat Pumps (ASHPs)Ground Source Heat Pumps (GSHPs)
Energy Efficiency Ratio (EER)ASHPs use the EER as a measure of their efficiency, indicating the cooling energy generated for each unit of energy used. Factors that can impact the EER include outdoor temperature, condenser capacity, and the type and size of the compressor coils and blowers. ASHPs might have lower efficiency in very cold temperatures due to higher outdoor air resistance.GSHPs do not primarily use EER for efficiency measurements, hence direct comparison may not be applicable.GSHPs might have more stable performance due to their operation in steady ground temperatures.
Seasonal Coefficient of Performance (SCOP)ASHPs also use SCOP to measure their seasonal performance. The SCOP might be lower in colder climates due to larger temperature differences between the air source and the indoor temperature. Efficiency can vary significantly over different seasons due to fluctuating outdoor air temperatures.GSHPs use SCOP as their primary efficiency measurement.GSHPs usually achieve higher SCOP as the ground temperature is relatively constant and typically closer to the desired indoor temperature.GSHPs’ performance tends to be more consistent across different seasons due to stable ground temperatures.

Environmental Impact Of Air Source And Ground Source Heat Pumps

Both air-source and ground-source heat pumps have environmental impacts, including greenhouse gas emissions, using various refrigerants to extract heat energy from outside sources, and potential noise pollution.

Carbon Footprint

Air source and ground source heat pumps, also known as GSHPs and ASHPs, respectively, are powered by electricity to provide useful heating and cooling. Air-source heat pumps use refrigerants to take energy from the air, while ground-source heat pumps take energy from the earth’s surface.

ASHPs generate more emissions than their geothermal counterparts since they use fluorocarbons, which add approximately 20% to their total carbon footprint due to power generation alone.

GSHP systems, however, have a much lower impact due to their efficient use of renewable energy, i.e., geothermal sources such as the earth’s surface or water resource drains usually present near urban areas.

In addition, they produce 75% to 85% fewer CO2 emissions than traditional gas-powered systems when providing low-temperature (heating) functions across all climate conditions.

Use Of Refrigerants

Refrigerants are compounds used in heat transfer applications to absorb and release thermal energy. Ground-source (geothermal) heat pumps commonly use hydrofluorocarbons (HFCs), while air-source heat pump systems may rely on chlorofluorocarbons (CFCs).

HFCs, such as R-410a, have very low ozone depletion potential but a higher global warming potential from producing HFC gasses when released by an air conditioner unit.

CFCs have virtually zero ozone depletion potential, but these can contribute up to 3 times more carbon dioxide emissions into the atmosphere than other alternatives upon release.

As such, using alternative types of refrigerant is one way for consumers to reduce their environmental impact and helps combat climate change.

Noise Pollution

Heat pumps generate some noise, including air and ground source heat pumps. The level of noise generated varies across types of models from different manufacturers.

Ground source heat pumps can reach up to 42 decibels, while the sound from an air-source model may vary widely depending on that specific unit and installation requirements.

Apart from type, factors like installation patterns and fan speed also contribute to their disruptive sound levels. Potential solutions like selecting appropriate units with enough isolation and adequate support structures during installation can help reduce excessive noise from air or ground systems.

Cost-Effectiveness Of Air Source And Ground Source Heat Pumps

Understanding the initial installation costs, long-term energy savings, and maintenance requirements for both air-source and ground-source heat pumps can help you decide which type of system is best for your home.

Initial Installation Costs

Initial installation costs are crucial when deciding between an air source and a ground source heat pump. These costs can vary significantly depending on several factors, including the size of the property, the type of system being installed, and the property’s location. The following table provides a comparison of the initial installation costs for air-source and ground-source heat pumps:

Type of Heat PumpAverage Cost Range (Unit and Installation)
Air Source Heat Pump$3,500 to $7,500
Ground Source Heat Pump$10,000 to $30,000

The table shows that air-source heat pumps have a lower initial installation cost than ground-source heat pumps. This difference is mainly due to the complexity of the installation process for ground source heat pumps, which require extensive excavation and drilling. 

Moreover, the property’s location can impact the installation cost since properties in colder climates may require more powerful heat pumps. Additionally, the size of the property will determine the capacity of the heat pump needed, with more significant properties requiring more powerful systems that come at a higher cost. For example, a large home’s high-quality ground source heat pump can cost up to $45,000 or more.

In conclusion, initial installation costs for air-source and ground-source heat pumps can vary significantly based on several factors. While the lower installation cost of air source heat pumps may be attractive, it is essential to consider the long-term savings, efficiency, and suitability for your specific needs before deciding.

Long-term Savings

The savings associated with air-source and ground-source heat pumps must be assessed in the short and long term. While it is true that an air source heat pump may require a smaller initial investment, depending on factors such as the size of the home and energy efficiency ratings for both systems, this lower cost may not always translate into long-term savings when compared to a ground source system.

Over time, if the necessary conditions are met, operating costs can be significantly reduced due to efficiencies gained from geothermal’s ability to store underground Energy Ratings (EER), typically 6-15 points higher than Air Source Heat Pumps (ASHP).

Ultimately, the expected lifespan of each system should also factor into decision-making; studies have shown that ASHP usually last 10–15 years while GSHPs have lifespans of 20–25 years.

Maintenance Costs

Regular maintenance is essential for the longevity and efficiency of all heat pumps, regardless of whether they are ground or air sources. Air source heat pumps require cleaning filters regularly to ensure efficient functioning and replace parts such as fan motors, compressors, and capacitors.

The overall cost of these repairs can range from $200 to over $2,000, depending on the abovementioned factors. On the other hand, ground source systems require hermetically-sealed pipes laid deep in trenches with earth loops; these must be checked periodically to ensure no damage has occurred after installation.

Repairs will incur costs if any significant changes have occurred within the system, including pipe breaks or severe leaks. These are often more important than those incurred by air source solutions due to more profound digging efforts in their installation process.

Which Heat Pump Is Better For Small Homes?

For smaller homes, air source heat pumps require less physical space than ground source ones due to their shallower soil requirements.

Space Requirements

When it comes to air-source heat pumps and ground-source heat pumps, the space requirements of each type may affect your decision. Ground source / geothermal systems require an outdoor location for a loop field that is connected to the system, so they need sufficient external land available or nearby.

The size of this field will depend on the requirement of your property but can usually be located in a yard, garden, or even under a driveway in some cases. On the other hand, air source heat pumps are more flexible as they don’t need underground piping; instead, their condenser units can typically be installed next to the house without too much intrusion into existing external spaces.

However, noise levels should be taken into consideration when installing an air source unit outside due to potential disruption caused by vibrations from its fan motors and compressors.

In terms of energy efficiency and performance in colder temperatures, ground source systems tend to perform better than their counterparts as well as save up energy due to the use of renewable sources such as the earth’s natural thermal energy stored beneath its surface.

Advantages And Disadvantages of Air source heat pumps and ground source heat pumps 

Air Source Heat Pumps (ASHPs)Ground Source Heat Pumps (GSHPs)
Cost-EffectiveInitial installation cost: $2,500 – $10,000Installation cost: Up to $20,000
Quick InstallationRequires less installation time than GSHPsLonger installation time
Space RequirementsRequires less spaceRequires more space
MaintenanceMaintenance cost: $400 – $600 per yearMaintenance cost: $900 – $1,500 per year
PerformanceLess energy-efficient in colder climates, affected by hot weather conditionsHigher energy efficiency across all climates
Noise LevelsTypically produces lower noise levels
Long-Term Utility CostsMay help offset utility costs in the long run

Which Heat Pump Is More Suitable For Colder Climates?

Ground-source heat pumps are more suitable for colder climates because they can utilize consistent temperatures below the earth’s surface. In contrast, air-source heat pumps generally rely on outside air, which can be significantly cooler during winter.

Performance In Cold Temperatures

Ground-source and air-source heat pumps are increasingly becoming famous for heating homes as they provide an efficient alternative to traditional methods. As the name suggests, ground source heat pumps (GSHP) extract thermal energy from underground sources such as natural groundwater, while air source heat pumps (ASHP) use outdoor air as their primary energy resource.

Regarding performance in cold temperatures, GSHPs tend to fare better because of their connection to gravity-fed sources that do not need a fan or compressor like ASHPs require.

Moreover, due to the constant temperature of below-ground ecosystems, unlike ambient temperatures, which fluctuate significantly for seasons, GSHPs experience lower compression loss during colder months, resulting in greater overall efficiency than their air-borne counterpart.

It is important to note that both systems have a defrost cycle where the unit heats the coils so that any frozen condensate can be melted away. However, these cycles differ between ASHP and GSHP; one type might offer additional benefits based on one’s climate conditions.

In some cases, it may also be necessary to install extra insulation around specific system components to improve its effectiveness further when operating in colder climates.

Defrost Cycle

Air source heat pumps require a defrost cycle when the temperature drops below 32 degrees Fahrenheit to maintain efficiency and performance.

In cold climates, the outdoor coils of air source heat pumps tend to freeze up, which reduces their ability to extract warm air from the outside. The defrost cycle helps unfreeze the coils, thus allowing the unit to absorb energy from the external environment and provide warmth indoors.

The importance of this additional feature was highlighted by Consumer Reports, which studied how modern heat pumps could be used instead of traditional heating systems in cold climates.

It found that despite needing additional features like a defrosting cycle, current models still performed better than older generations in most cases, mainly due to improved technology available today, such as variable-speed compressors for enhanced system capacity control.

Eco-Friendly Options In Ground Source and Air Source Heat Pumps

  1. Use of Renewable Energy
    • Heat pumps powered by renewable energies (geothermal, solar, wind) are effective in reducing carbon emissions and mitigating climate change.
    • Switching from traditional fossil fuels to renewable sources for home heating and cooling systems offers long-term cost savings.
    • Geothermal heat pumps utilize natural temperature differences below ground level to extract thermal energy without generating additional greenhouse gasses, making them suitable for warmer climates.
    • Solar-powered air source heat pumps provide a sustainable alternative to polluting heating options. They generate Photovoltaic electricity that can be used directly or stored for later use.
    • Wind-powered ground source heat pumps have potential due to advances in turbine technology, making them more affordable and easier to install compared to previous models.
  2. Carbon Offsetting
    • Carbon offsetting is a voluntary method to reduce the environmental impact and compensate for greenhouse gas emissions.
    • Carbon offsets involve actions that decrease the net amount of carbon dioxide emitted into the atmosphere, such as reducing emissions elsewhere or sequestering carbon through projects like tree planting.
    • With heat pumps, carbon offsetting can be achieved by using renewable energy sources (e.g., solar power, geothermal heat) instead of fossil fuels, leading to zero-carbon heating systems.
    • Offset programs can also facilitate the adoption of clean technological solutions integrated with existing HVAC systems, resulting in lower energy consumption while maintaining high efficiency.
    • Carbon offsetting helps minimize the environmental impact of air source and ground source heat pumps through waste reduction and the development of more efficient heating methods.

Comparing Noise Levels In Air Source And Ground Source Heat Pumps

Air-source heat pumps are noisier than ground-source heat pumps, causing more noise pollution in the home.

AspectAir Source Heat PumpsGround Source Heat Pumpss
Noise LevelTend to be noisierGenerally quieter
Factors Affecting Noise LevelsPoor installationSuboptimal placementEquipment type used Optimal outdoor placementEquipment type used Refrigerant change
Noise Reduction SolutionsAcoustic barriersSound-absorbing materialsNoise-reducing accessoriesAcoustic barriersSound-absorbing materialsNoise-reducing accessories
  1. Noise Level:
    • Air Source Heat Pumps: Air source heat pumps tend to be noisier compared to ground source heat pumps.
    • Ground Source Heat Pumps: Ground source heat pumps are generally quieter in operation.
  2. Factors Affecting Noise Levels:
    • Poor installation: Proper installation is crucial in minimizing ambient noise. A poorly installed system can emit higher sound levels than normal.
    • Suboptimal placement: Installing the unit in a confined space or an unsuitable outdoor location can significantly increase the noise output.
    • Equipment type used: The type of equipment, such as compressors, can affect the noise emission. Some compressor types may be louder than others.
  3. Noise Reduction Solutions:
    • Acoustic barriers: The use of acoustic barriers, such as fencing or walls, can help absorb sounds by absorbing energy from the waves generated by the heat pump’s operation.
    • Sound-absorbing materials: Applying sound-absorbing materials like foam boards, fiber mats, panels, or rubber sheets to components such as fan blades can help contain the noise within the system.
    • Noise-reducing accessories: Accessories like silencers, which are connected between the indoor and outdoor units of a heat pump system, can help reduce noise levels, particularly during the operation of the quieter components.


1. What is the difference between an air source and a ground source heat pump?

An air source heat pump uses outside air as its energy source, while a ground source or ‘geothermal’ heat pump uses energy from the ground. Air Source Heat Pumps are typically cheaper to install than ground source due to their simpler set up requirements, but Ground Source Heat pumps can provide higher levels of efficiency for larger applications in particular.

2. Which type of system is more reliable?

Ground source systems tend to be more reliable because they have fewer moving parts and are usually not exposed to weather conditions like wind and rain which can affect an air source’s performance negatively over time. Additionally, geothermal pumps use underground temperatures which remain much more consistent than those in the atmosphere above them resulting in longer-lasting systems with lower maintenance costs overall for homeowners.

3. What advantages does each type of heating system offer?

The major advantage offered by an Air Source Heat Pump (ASHP) over a Ground Source one is cost; ASHPs are typically less expensive to purchase and install compared to GSHPs and require only very basic installation requirements such as access points for outside air intake tubes or grills on exterior walls where the unit will be mounted outdoors if necessary for correctly powering unit indoors via electric connection conduit(s). On the other hand – GSHPs are generally better suited especially when considering large-scale usage/distribution needs, particularly in areas with very cold winters since these systems don’t rely solely on outdoor temperature & instead use thermal energy stored within Earth’s subsurface layers supplied via horizontal/vertical loop fields facilitating constant indoor climate control 365 days year regardless environmental conditions present around structure being heated/cooled

4. Is installing one type better than the other under certain circumstances?

Yes – depending upon the individual situation either may prove suitable however it’s essential to consider all factors prior to settling a decision i.e., size building thought process existing infrastructure; available budget initial outlay installation fees running expenses etcetera when comparing both types ensure selecting the best fitting solution fulfillment specific goals outline beforehand depending what actual preference based off regarding future comfort desired whatever situation ultimately presents itself


When deciding between air-source and ground-source heat pumps, weighing the essential factors for individual situations is crucial. Ground source heat pumps are significantly more efficient due to their use of constant temperatures below the earth’s surface but will cost much more initially in installation costs.

Air-source heat pumps have lower installation costs yet reduce heating bills by approximately 50% compared to electric furnaces, making them an excellent option for those on a budget.

However, they are less efficient than ground source systems and require more maintenance and larger spaces than geothermal systems. Additionally, noise levels produced by air source pumps can be higher than that of vertical or horizontal types (ground) pumps. However, soundproofing solutions exist to address this issue should it become an issue.

Heat Pump