Air source heat pump vs ground source heat pump: which is best?

Air source heat pump vs. ground source heat pump – there are numerous considerations to make in deciding which option is best suited for your home.

This article provides a concise overview of the key considerations to weigh up if you’re considering switching to a heat pump.

We look at the main differences between an air source vs ground source heat pump, including the costs of supply and installation, efficiency, longevity, practicalities and more.

Are ground source heat pumps better than air source heat pumps?

A common question around heat pumps is whether one type is better than the other.

Installing a heat pump is a major investment that will reap long-term benefits, so you’re right to research your options thoroughly.

While there are significant differences in cost and efficiency, often the decision is made easier by assessing whether you have the physical space for a ground source heat pump.

A ground source heat pump typically requires between 600 – 1,200 square metres of land to install.

Without this, an air source heat pump, by default, could be the most suitable option for your home.

How do heat pumps work?

Heat pumps are a type of eco-friendly heating system that absorbs heat from the environment to heat your home.

The heat that’s extracted from the environment is transferred to a fluid and compressed to increase its temperature.

The heat is then passed into your home’s central heating system for you to enjoy as heating and hot water.

The key difference between air source and ground source heat pumps is their source of heat

• Air source heat pumps (ASHPs) take heat from the surrounding air
• Ground source heat pumps (GSHPs) absorb heat from the ground

Air source vs ground source heat pump efficiency

When comparing which is more efficient: a ground or air source heat pump, the biggest factor at play will be the ‘source’ temperature. Where you live and your climate will therefore be a key point of consideration.

If you live somewhere that regularly experiences very cold air temperatures, a ground source heat pump may be more efficient across the year, as they tap into a more stable source of heat.

In this circumstance, an approved heat pump installation specialist will be able to advise whether the potential energy savings of a GSHP outweigh the (higher) cost of installation.

Coefficient of Performance (COP)

Another way to measure the efficiency of air source and ground source heat pumps is the Coefficient of Performance (COP).

This represents the ratio of useful heat produced (output) to energy consumed (input).

A higher COP has higher efficiency, lower energy consumption, and hence lower operating costs.

Installation considerations

Now we know how heat pumps work and what to look for in terms of efficiency, but what should you be aware of regarding the installation of a ground source vs air source heat pump?

As we mentioned earlier, a major factor in deciding which type of heat pump is right for your home is whether you have sufficient space for installation.

• An air source heat pump needs to be fitted to a wall or placed on the ground, located somewhere with good airflow, e.g. a garden rather than an alleyway
• A ground source heat pump requires pipework to be buried in the ground, which can cause significant disruption

How the pipework for a GSHP is laid has a major impact on the overall cost of installation – more on this later.

Suitability for different homes

According to a report issued by Scottish Power in collaboration with WWF, ground and air source heat pumps could increase your property value by up to 3%.

However, assessing which is better, an air or ground source heat pump depends on your needs and the specifications of your property.

A larger property will require a more powerful heating source, which will impact the cost of the heat pump you select.

However, your property’s insulation and heating requirements should also be considered.

Insulation

If your home is not insulated properly, the heating needs to work harder to maintain a consistent temperature.

To get the greatest benefits of a heat pump, your home therefore needs to be well-insulated.

These costs will help to budget for retrofitting your property with insulation, if needed:

• Upgrading wall insulation (cavity wall) costs around £2,000
• Upgrading roof insulation (blanket roll) sits in the region of £1,500
• Upgrading floor insulation is normally around £3,000

Heating requirements

In general, radiators for a heat pump system need to be two and a half times larger than normal to provide the same heat output.

Upgrading your heating could cost:

• £3,000 for ten larger radiators
• £10,000 for underfloor heating

Related content: Learn more about the cost of underfloor heating.

Environmental impact

Reduced energy bills and lower carbon emissions are two of the direct benefits of installing a heat pump. Both of these can make your property more attractive to buyers, hence increasing your home’s value.

Ground and air source heat pumps could cut your home’s carbon emissions by 90%.

However, comparing the environmental impact of a ground source heat pump vs air source, ground source heat pumps come out on top as the lowest carbon heating system.

Maintenance and lifespan

Despite the initial upfront cost of heat pumps, bear in mind this is a long-term investment.

Ground source heat pumps require very little maintenance and last for around 15 years (or up to 50 if well maintained!) because their components are mainly underground, protected from the elements.

Air source heat pumps also have an impressive lifespan of between 15-20 years.

An annual service is recommended to make sure the system is working efficiently and to maintain the manufacturer’s warranty.

Air source vs ground source heat pump cost

Evaluating air source vs ground source heat pump cost will help you to make an informed decision. As a general rule, air source heat pumps are typically cheaper but offer a lower return on investment.

Supply and installation costs

On average, a ground source heat pump costs somewhere in the region of £18,000 - £50,000.

The initial cost of a ground source heat pump is made up of the cost of the equipment (about 50% of the total cost) and the cost of the installation.

The most significant chunk of the installation cost comes from the groundwork or drilling required to lay the heat exchange pipework.

There are two types of ground source heat pumps available – vertical ground source heat pumps and horizontal ground source heat pumps.

It’s worth noting that the groundwork for vertical boreholes is usually about twice as expensive as that for horizontal trenches.

In general, the cost of installing a ground source heat pump can be impacted by several factors:

• The pump type
• The pump size (big enough for your home)
• COP (Coefficient of Performance)
• Amount and level of heat needed
• Heat source temperature

Conversely, the supply and installation of an air source heat pump will cost in the region of £2,000-£20,000.

There are two types of air source heat pumps available. Air-to-water is the more expensive option, costing around £15,000 for supply and installation, vs around £3,000 to supply and install an air-to-air system.

As with a ground source heat pump, several factors will impact the cost of an air source heat pump:

• The size of your property
• The type of pump you choose
• The pump brand
• The pump’s performance and efficiency
• The amount and level of heat required

Green energy grants or incentives for heat pumps

Despite the initial high investment of installing a heat pump, the government’s Boiler Upgrade Scheme (BUS) can help toward the cost.

The scheme runs from 2022-2025. It’s open to all UK homeowners and could see you receive up to £7,500 towards your air source or ground source heat pump.

Find and hire a certified heat pump specialist

On balance, if you have a smaller plot of land and a more modest budget, an air source heat pump is likely to be the most suitable option for your home.

However, for a significant home improvement such as this, we recommend consulting with a professional before making a decision.

Find and hire an MCS-accredited installer for your heat pump, with Checkatrade. Search your postcode to find top-rated professionals in your area.

Summary

With plenty of information to consider before selecting the best heat pump for your home, here’s a summary to help evaluate the main points we’ve outlined:

Ground source heat pumps are typically the best option if you:

• Have sufficient land
• Are willing to make a long-term investment
• Have a larger budget
• Want a quieter system
• Want low maintenance

On the other hand, air source heat pumps may be more suitable if you:

• Have limited space
• Want a lower initial investment
• Want quicker installation
• Want a faster ROI
• Want a less intrusive solution

These aren’t the only things to consider, but they’re some of the main points of concern for most people.

FAQs

Is a ground source heat pump cheaper to run than an air source heat pump?

As well as the ‘source’ temperature and the COP of your heat pump, you must also factor in the required room temperature when considering efficiency.

Heat pumps are designed for a temperature of 50c. You will get lower efficiency if you require higher temperatures, resulting in higher running costs.

Do I need planning permission to install a heat pump?

Air source heat pumps also require planning permission in some cases, so be sure to run the project by your local council before committing to anything.

In most cases, ground source heat pumps fall under permitted development and therefore will not require planning permission.