Air Source Heat Pump (ASHP) vs Ground Source Heat Pump (GSHP): A Comprehensive Comparison
When considering renewable energy systems to heat your home, two of the most popular options are Air Source Heat Pumps (ASHPs) and Ground Source Heat Pumps (GSHPs). Both systems offer efficient, eco-friendly heating solutions that can reduce your carbon footprint and lower your energy bills. However, they have key differences that make each more suitable for specific situations.
In this blog, we’ll explore the fundamental differences between ASHPs and GSHPs, comparing their costs, efficiency, installation processes, and suitability to help you decide which is the best option for your home.
What is an Air Source Heat Pump (ASHP)?
An Air Source Heat Pump (ASHP) absorbs heat from the air outside to provide heating and hot water for your home. Even in cold weather, an ASHP can extract heat from the air, making it a highly energy-efficient solution for residential heating. This renewable energy system works by compressing refrigerant fluid, which increases the temperature of the extracted heat, and then transferring it to your home’s heating system.
ASHPs can also function as air conditioners during the summer months, making them a versatile, year-round solution for both heating and cooling needs.
Key Features of an ASHP:
- Outdoor installation: Mounted on an external wall or installed on the ground.
- Dual functionality: Provides both heating and cooling.
- Operating temperature range: Efficient even in sub-zero temperatures.
- Relatively simple installation: Compared to GSHPs, they are easier and quicker to install.
What is a Ground Source Heat Pump (GSHP)?
A Ground Source Heat Pump (GSHP), on the other hand, uses the earth’s natural heat stored below the surface to provide heating and hot water. GSHPs require the installation of a network of pipes (called a ground loop) either horizontally or vertically under the ground. The system pumps water through these pipes to absorb heat from the ground, which is then transferred to the refrigerant in the heat pump for use in your home.
The temperature underground remains fairly constant throughout the year, meaning that GSHPs are extremely efficient in all weather conditions.
Key Features of a GSHP:
- Buried ground loop: Installed underground, either horizontally or vertically.
- Highly efficient: Reliable performance regardless of outdoor temperatures.
- Quiet operation: Minimal noise compared to ASHPs.
- Longer lifespan: Due to fewer moving parts and protected components.
Efficiency Comparison: ASHP vs. GSHP
ASHP Efficiency
Air source heat pumps are generally highly efficient, with a Coefficient of Performance (COP) between 3 and 4. This means that for every unit of electricity consumed, an ASHP can produce three to four units of heat. However, their efficiency can drop as outdoor temperatures fall, particularly in extreme cold. Modern ASHPs are designed to operate in temperatures as low as -15°C, but their performance may decrease during very cold winters.
GSHP Efficiency
Ground source heat pumps are typically more efficient than air source systems, with a COP ranging from 4 to 5, meaning they can deliver four to five times the energy they consume. Since the ground maintains a constant temperature, GSHPs are less affected by weather conditions, making them more consistent and efficient year-round.
Installation: What’s Involved?
ASHP Installation
Air source heat pumps are simpler and quicker to install compared to ground source systems. An ASHP unit is usually mounted outside the property, typically on an external wall or on the ground near the home. The installation involves some basic pipework to connect the heat pump to the central heating system. For most homes, the entire process can be completed within a few days, with minimal disruption to the property or landscaping.
GSHP Installation
Ground source heat pumps, however, require more complex installation, mainly due to the ground loop. The type of installation depends on the available space:
- Horizontal ground loop: Requires a large amount of land (e.g., a garden) to install pipes over a wide area.
- Vertical ground loop: Involves drilling deep boreholes into the ground, making it more suitable for properties with limited land.
While GSHP installations take longer and are more invasive, they are often the better choice for homes in rural areas with larger plots of land. After installation, the ground above the loop can be used as normal, for example, for gardening or parking.
Cost Comparison: ASHP vs. GSHP
ASHP Cost
Air source heat pumps are generally more affordable to install. On average, an ASHP costs between £7,000 and £12,000 for installation in the UK. This makes them an attractive option for many homeowners looking to switch to renewable energy without breaking the bank. Government incentives, such as the Boiler Upgrade Scheme (BUS), offer grants of up to £7,500 towards the cost of installation, further reducing the upfront expense.
GSHP Cost
Ground source heat pumps are more expensive to install due to the excavation work required for the ground loop. Installation costs typically range from £15,000 to £30,000. However, GSHPs are eligible for the same Boiler Upgrade Scheme grants, with up to £6,000 available for installation. While the upfront cost is higher, the long-term energy savings and durability of the system can make it a more cost-effective option over time.
Suitability for Homes
ASHP Suitability
Air source heat pumps are ideal for homes in urban or suburban areas where space is limited. Since they don’t require a large outdoor area, ASHPs can be installed in most properties, provided there’s sufficient external wall space or a small yard for the outdoor unit. They are also a good option for retrofit projects where minimal disruption is preferred.
GSHP Suitability
Ground source heat pumps are best suited for homes with larger plots of land, particularly in rural areas. The installation of a ground loop requires significant space for horizontal loops or the ability to drill deep boreholes for vertical loops. If you’re building a new home or undergoing major renovation, a GSHP can be a highly efficient long-term solution.
Maintenance and Lifespan
ASHP Maintenance
Air source heat pumps require regular maintenance, including cleaning the external unit, checking refrigerant levels, and ensuring the system is free of debris. With proper maintenance, an ASHP can last for 15 to 20 years.
GSHP Maintenance
Ground source heat pumps have fewer moving parts, meaning they typically require less maintenance than ASHPs. Once installed, the underground loops can last for over 50 years, while the heat pump itself has a lifespan of 20 to 25 years.
Environmental Impact
Both ASHPs and GSHPs significantly reduce carbon emissions compared to traditional heating systems like gas boilers. However, GSHPs tend to have a smaller carbon footprint due to their higher efficiency. When powered by renewable electricity, either through solar panels or green energy tariffs, both systems can provide near-zero carbon heating.
Which is Better: ASHP or GSHP?
The decision between an ASHP and GSHP depends on several factors, including your budget, available space, and heating needs.
- Choose an ASHP if you’re looking for a more affordable, easier-to-install system and you have limited outdoor space. They are an excellent option for both urban and rural homes.
- Choose a GSHP if you have more land, a higher budget, and want the most efficient, low-maintenance heating solution. GSHPs are perfect for long-term investments in energy efficiency and rural properties with space for a ground loop.
Both Air Source Heat Pumps (ASHPs) and Ground Source Heat Pumps (GSHPs) offer fantastic energy-efficient heating solutions. ASHPs are more affordable and quicker to install, while GSHPs offer superior efficiency and long-term savings. Regardless of which system you choose, both can drastically reduce your energy bills and carbon footprint, making them a great investment for eco-conscious homeowners.
If you’re ready to install a heat pump, why not post a job on BookaBuilderUK.com and find a qualified installer today? Take the first step towards a more sustainable and energy-efficient future!
