🌿 Air-Source vs Ground-Source Heat Pumps: Which Is Best for Your Home?

If you’re planning sustainable heating and cooling for your home, heat pumps will probably be your first choice – both for their efficiency and lower carbon emissions. There are two main types: air-source and ground-source. In this article, we’ll outline the differences between them, and the particular benefits and drawbacks of each. It’s important to think about your options carefully before committing, as the choice will affect the running costs and the look and feel of your home. It’s worthwhile comparing the potential running costs of different options on a seasonal basis before you decide. Climate, property size and your initial budget all play a key role in determining which system is right for you.

Air-Source Heat Pumps (ASHPs)

ASHPs work by extracting heat from the outside air, which is pulled in by a fan that pulls air over refrigerant-filled coils. ASHPs are more common than GSHPs and are also generally less expensive to install than GSHPs because they require no digging or excavation.

Advantages of ASHPs:

• Lower installation costs: installation is usually simple and straightforward, with few major groundworks required, compared with GSHPs, so it’s less disruptive and cheaper.
• Flexibility: an ASHP can be installed in many different kinds of homes – from flats to detached houses – and is particularly suited to urban environments that might have limited areas of ground space.
• Good Performance: Modern ASHP units can operate even at −15°C temperatures, but the performance decreases as the outdoor temperature lowers.

Disadvantages of ASHPs:

• Lower efficiency in cold climates: It works but, in very cold climates, its performance and efficiency can decrease compared with GSHPs.
• Dependency on Outside Temperatures: Their efficiency is directly affected by ambient air temperature, and they are thus less predictably efficient than GSHPs.
• Likelihood of Noise: Exterior fans can add noise potential to an installation, which could be an issue in highly populated areas.

Ground-Source Heat Pumps (GSHPs)

GSHPs use the constant underground temperatures to heat and cool buildings. GSHPs involve circulating liquid (water and antifreeze mixture) in a closed loop of piping buried underground. The constant temperatures of the ground are favourable for heating and cooling.

Advantages of GSHPs:

• High Efficiency: GSHPs are generally more efficient than ASHPs, since ground temperatures are more stable than air temperatures, thus allowing them to operate at high efficiencies all year round.
• Quiet operation: All the major components are below or indoors, making these systems quieter than ASHPs and creating minimal noise.
• Lower Running Costs: The operational costs are lower in the long run, because they are more efficient, especially lower temperatures where ASHPs perform poorly.

Disadvantages of GSHPs:

• Higher initial installation costs: the excavation is necessary and can make the GSHP installation expensive and complicated.
• Land: Sufficient space is necessary for a ground loop, which is often not feasible for all property types and sizes.
• Longer period of return: Since the cost is very high, the payback period is quite long compared to ASHP.

Summary Both air-source and ground-source heat pumps are effective ways of heating and cooling your home while saving money and reducing energy use and your carbon footprint. Taking into account your home’s location, size and your specific long-term energy savings goals, you can find the system that best meets your needs, providing the best combination of benefits. Regardless of whether you install an ASHP or a GSHP, switching to a heat pump is a step toward a more energy-efficient, low-carbon home.