Ground source heat pumps vs air source heat pumps

Thermatic Homes are experienced installers of both air source heat pumps and ground source heat pumps, installing them for housing associations across the UK – so we thought we’d take a look at the key differences between the two, to help you make a more informed decision for heating your homes efficiently.

There are so many things to think about when you’re choosing a heat pump. From the costs and efficiencies of each system to the practicalities of installation and available space at your property (inside and out).

Did you know that one of the main reasons people install energy efficiency home upgrades is to save money on their energy bills? People who have cold homes are most likely to investigate this technology.

With help from financial support schemes such as the Renewable Heat Incentive (RHI) and for people who live in Scotland, the Scottish Government have something called a Home Energy Scotland Loan, making it more cost-effective to install renewable heating systems than ever before.

How do heat pumps work?

Heat pumps work by absorbing heat from the environment and transferring it into a fluid, which is then compressed to increase its temperature which is then transferred from the fluid into the central heating system, to use to heat your home and your water.

What’s the difference between an air source heat pump and a ground source heat pump?

The main difference is where they get the heat from. Ground source heat pumps absorb heat from the ground and air source heat pumps, absorb heat from the air.

For information on air source heat pumps and how they work, check out our blog on air source heat pumps.

How much do heat pumps cost?

The cost of installing each heat pump differs. But some cost factors are very similar including:

The size of your house.

Whether it’s a new build or an old house (newbuild helps keep costs down as they tend to be better insulated).

The amount of preparation works that need to be done for the conversion, for example, you might need a new electricity supply from your fuse box to the location of the heat pump.

Your installer might make the recommendation to upgrade your radiators to improve energy efficiency.

How much does a heat pump cost?

On average, an air source heat pump costs anywhere between £5,000 – £13,000. Whereas a ground source heat pump costs anywhere between £13,000 – £19,000. The extra cost for the GSHP comes from the external work in the garden as boreholes need to be installed.

However, in spite of the larger upfront cost of installing a ground source heat pump, they tend to be more efficient in heating your home which = lower energy bills and larger fuel savings. Another bonus is the RHI payments are a lot higher, which means in the long term you’ll save more money.

How efficient are heat pumps?

ASHPs work with air temperatures which ebb and flow between -5°C to 25°C for the majority of the year, but there are some days when it gets much colder and much hotter, but this temperature bracket does cover at least 95% of days in the year.

With ground source heat pumps extracting heat from the soil, temperatures don’t get as high but they also don’t tend to drop below freezing and it tends to stay above 5°C all year round (as long as the ground loops have been installed properly).

What does this mean?

Sometimes in the year, an air source heat pump will be more efficient than a ground source heat pump, but when it gets to the colder temperatures, the GSHP will be much more efficient.

ASHP do not need to use energy to pump fluid around the pipework outside (which happens with a GSHP). Therefore, on days when the air is the same temperature as the ground, an ASHP can still be slightly more efficient.

Nevertheless, overall – ground source heat pumps are more efficient over the course of the year, but any additional cost savings will vary on where you are in the country and the environmental conditions. For example, the further North you are in the country, the easier it is to justify the extra cost of a ground source heat pump.

Which one should you choose?

If you’re constrained by budget or space restrictions, then an air source heat pump would be the best choice, however, if this isn’t the case, you’ll need to take your time to consider the needs of your home or houses if you’re a housing association.

If you’re unsure about which heat pump to choose, we can help you find the right solution for your needs.

You can call us on 0161 543 4128 or email us at information@thermatichomes.com