Air Source vs Ground Source Heat Pumps in the UK

Air source heat pumps come with a lot of advantages such as being easier to install, typically more affordable upfront and requiring less outdoor space compared to other home heating options. They’re a popular choice for many people, helping cut down energy bills while reducing carbon footprint.

However, you’ve probably also heard about the benefits of ground source heat pumps, which use the stable temperature underground to deliver consistent and efficient heating. With so much information out there, it can become confusing if you’re trying to decide between an air source or ground source heat pump.

That’s where we hope this article can help. By clearly comparing these two types of systems, you’ll understand which option could suit your home as well as why more people are choosing air source heat pumps like the Vaillant aroTHERM plus.

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How Do Air and Ground Source Heat Pumps Work?

Heat pumps work by moving heat from one place to another, rather than generating heat directly. They extract heat from either the air, ground or water outside your home and transfer it inside to warm your living space. They're an energy-efficient alternative to traditional heating systems like boilers.

Here’s how the two main types work:

• Air Source Heat Pumps: These systems absorb heat from the outside air, even when it's cold outside. The heat is captured by a refrigerant fluid which is then compressed to increase its temperature. This heat is transferred inside your home through your heating system, providing warmth and hot water. If you want more comprehensive information, you can read our guide on how air source heat pumps work.

• Ground Source Heat Pumps: These pumps extract heat from the consistent temperature below the ground. Pipes buried underground circulate a fluid that absorbs heat from the earth. This heat is then compressed and distributed inside your home to provide steady, efficient heating.

There’s also a third type called water source heat pumps. These systems work similarly by drawing heat from a nearby water source, like a lake or river, but they’re quite uncommon in the UK due to limited suitable locations and stricter regulations.

While they can be very efficient where conditions allow, most people typically choose air source or ground source heat pumps instead.

What Are the Similarities between Air and Ground Source Heat Pumps?

Now that you understand how air source and ground source heat pumps work, let's look at some key similarities between the two:

• Both harness renewable energy by extracting natural heat from the environment to warm your home efficiently.

• They operate on the same basic principle, moving heat rather than generating it, which helps reduce energy consumption and carbon emissions.

• Both systems provide heating and can supply hot water, working with your existing or new radiators, as well as underfloor heating.

• Each requires an outdoor component. Air source heat pumps have an outdoor unit, while ground source heat pumps use underground pipe loops to collect heat.

• Both are environmentally friendly alternatives to traditional boilers and can lower your energy bills over time.

• They often need a hot water storage tank or cylinder inside your home to store the heat they produce.

• Service and maintenance are similar, involving routine checks to keep the system running efficiently.

• They can integrate well with solar panels, further boosting your home's renewable energy use. Read our article on 'can solar panels power a heat pump?' for more information.

Air Source vs Ground Source Heat Pumps - How Are They Different?

Now that we've gone through the similarities between air source and ground source heat pumps, let's look at each way they are different. Ultimately, how they differ will help you decide which option is right for your home and needs:

Outdoor Space and Installation Needs

One of the biggest differences between air source and ground source heat pumps is the amount of outdoor space and preparation required. Air source heat pumps, like the Vaillant aroTHERM plus that we install at Glow Green, need relatively little outdoor space. They come with an outdoor unit that can be mounted on a wall or placed on the ground in your garden, requiring only good airflow around it. This makes air source pumps easier and quicker to install, especially if you have limited outdoor space.

On the other hand, ground source heat pumps require a significant amount of outdoor space because they rely on pipes buried underground to collect heat from the earth. These pipes can be laid horizontally, needing a large garden area, or they can be installed vertically using deep boreholes that require specialist drilling. This can mean higher installation costs, longer setup times and more disruption to your garden. So, if space is tight or you want a simpler install, an air source heat pump is often a better fit.

Helpful Reading: Where is the Best Place to Install an Air Source Heat Pump?

Installation Costs

When it comes to upfront expenses, air source heat pumps like the Vaillant aroTHERM plus generally cost less to install. This is because their installation is simpler and quicker, involving just the outdoor unit on your property and the internal connections.

Typically, the cost of an air source heat pump can be around £3,000 to £10,000 after government grants like the Boiler Upgrade Scheme.

In comparison, ground source heat pumps involve more complex groundwork, like digging trenches or boreholes to lay underground pipe loops, which can drive installation costs to more than double of what you would pay for an air source heat pump. These higher upfront costs reflect the labour-intensive process and specialist equipment required.

While ground source systems might deliver greater efficiency in the long run (more on this later), the initial price difference is a key factor to keep in mind when deciding between the two options.

This cost difference also explains why many people with limited budgets or space choose air source heat pumps, especially when combined with other renewable upgrades like solar panels.

Running Costs

When it comes to running costs, ground source heat pumps generally have the edge because they operate more efficiently year-round. They use the stable underground temperature which means they need less electricity to generate the same amount of heat.

On the other hand, air source models use more electricity in colder weather as they need to work harder, which can increase your bills during winter months when your heating needs are highest.

However, with a well-installed air source pump and a home suited to the system, running costs can be kept competitive.

Planning Permission

When it comes to planning permission, installing an air source heat pump is generally simpler. In most cases, air source units like the do not require planning permission if they meet certain size and noise limits and are mounted in typical locations such as a garden or wall. This makes air source heat pumps a more straightforward option for many people wanting a hassle-free installation.

Ground source heat pumps, however, can face more complex planning considerations. Since they involve groundworks, local authorities may require detailed permission to ensure the installation doesn’t negatively impact your land, nearby structures or protected areas. This process can take longer and involve additional surveys or permits, which adds to the overall planning timeline and complexity.

Year-Round Efficiency

Another significant differences between these two systems is how efficiently they operate in different weather conditions. Air source heat pumps absorb heat from the outside air. Their efficiency rises or falls depending on how cold it is outside. They tend to be less efficient during harsh winter temperatures because there’s simply less heat in the air for them to extract.

Ground source heat pumps work differently. They draw warmth from below the earth’s surface, where the temperature remains much more stable year-round, often around 5°C even in winter. Because of this, ground source systems can maintain a high efficiency nearly all the time%, and they don’t suffer drops in performance when outdoor temperatures decline. That predictability means you can potentially get lower running costs at certain times of the year.

While air source heat pumps deliver strong efficiency when properly installed and matched to your home, ground source systems still hold the advantage for overall efficiency throughout the year. Ultimately, choosing the best heat pump for your home isn’t just about efficiency, it also depends on your property, your budget and what matters most to you in a heating solution.

Helpful Reading: How Efficient Are Heat Pumps?

Noise Considerations

Air source heat pumps produce some noise mainly from their outdoor fan and compressor. Typically, they generate between 40 to 60 decibels, which is about the same as a normal conversation or a fridge humming. While this noise is generally not disruptive, it might be noticeable if the unit is placed close to windows or neighbour’s homes.

Ground source heat pumps are usually much quieter because they don’t have an external fan. Their noise mostly comes from indoor components like the compressor, roughly comparable to the sound of a quiet refrigerator. This makes ground source systems one of the quietest heating options you can choose.

So, if low noise is a priority in your decision, a ground source system can be a better fit. Though, with careful installation and location choices, air source heat pumps can also blend quietly into your home environment without causing disturbance.

Lifespan and Durability

Air source heat pumps, like the Vaillant aroTHERM plus that Glow Green installs, usually have a lifespan of around 20 to 25 years, with servicing and maintenance. Though, it's important to keep in mind that since they are installed outside and exposed to weather, factors like temperature changes and environmental conditions can affect their durability.

Ground source heat pumps, in contrast, often last longer. The underground pipe system that collects heat from the earth can last even longer, in some cases 100 years, since it is protected from the elements. This makes ground source heat pumps more durable in theory, though both provide many years of reliable service.

Environmental Impact and Sustainability

Both air source and ground source heat pumps offer huge sustainability benefits over traditional gas or oil boilers, mainly because they use renewable energy from the air or the ground. This helps you lower your home’s carbon footprint and rely less on fossil fuels.

However, there are some differences to keep in mind. Ground source heat pumps generally have the upper hand when it comes to overall environmental performance. This is because they’re more efficient year-round, they tend to use less electricity to produce the same amount of heat, resulting in even lower carbon emissions over time.

Air source heat pumps are still very eco-friendly. They work particularly well when combined with solar panels, something we can also help you with, allowing you to power your heating with green electricity straight from your roof. This can make your heating almost carbon neutral and maximise the sustainable benefits.

Helpful Reading: The Pros and Cons of Air Source Heat Pumps

Which Heat Pump is Right for Me?

You’ve probably started to get a clear sense of which heat pump might be best for you after exploring all the similarities and differences above. Ultimately, choosing between an air source and ground source heat pump often comes down to what suits your home, your budget and your overall priorities.

If you don’t have a large garden or you’re working with a tighter budget, an air source heat pump, like the Vaillant aroTHERM plus, is usually the better fit. That’s one of the main reasons air source heat pumps are more popular across the UK - most residential properties simply don’t have the space or the need for groundworks required by ground source systems.

On the other hand, a ground source heat pump could be perfect for you if you’ve got plenty of outdoor space and you’re looking for the peak in long-term efficiency, even if that means spending more upfront. These systems deliver some of the lowest running costs and carbon emissions available, but they do require a bigger investment and more installation work.

However, if you’re still unsure which option is right for your home, don’t worry, our team of heat pump experts at Glow Green are here to help. We can take a closer look at your property and circumstances, and give you honest advice about what will truly work best for you and your home.

At Glow Green, we’re proud to have been named one of the UK’s Best Solar Panel Installers for 2025 & 2026 by The Independent. You can expect the same award-winning expertise and professionalism from us when it comes to your heat pump installation.

Air Source vs Ground Source Heat Pumps FAQs