Air Source Versus Ground Source Commercial Heat Pumps
A common question we get asked by prospective customers is whether they should be installing an air source or ground source heat pump.
The answer, as always, is context dependent. At Clade we manufacture and install air or ground heat pumps depending on the specific requirements of the customer and the environmental conditions of the site.
In this blog we’re going to dive into the major differences between commercial air and ground source heat pumps and when they are and aren’t appropriate.
Commercial air source heat pumps
You’ll likely have seen air source heat pumps on commercial buildings before – they are typically installed outside or on the roof of a building. They represent about 87% of heat pumps in the UK.
This type of heat pump takes heat energy from the air and, using electricity to drive a thermodynamic cycle, transfers it to the interior of the building.
Air source heat pumps have a reputation for producing lower flow temperatures than conventional gas boilers. We consider this misleading because a heat pump which uses CO2 as the working fluid, such as the ones we make at Clade, can deliver temperatures that match those of conventional gas boilers.
This means that, for the people inside the building, there is absolutely no difference whether the room is heated by burning natural gas or running an air source heat pump.
Air source heat pumps can be less efficient when the outside air temperature is very low. They’ll still work perfectly well, but this does mean that for certain situations a ground source heat pump can be more attractive. Without noise abatement they are also noisier than ground source heat pumps. Finally they take up more above ground space as the heat collectors requires clear air flow to be effective.
Commercial ground source heat pumps
While air source heat pumps are still the most common in the UK, ground source heat pumps are becoming increasingly common across Europe and the USA.
A ground source heat pump uses a ground loop or borehole to extract heat from the ground but otherwise functions in the same way as an air source heat pump.
Ground source heat pumps are generally more efficient than air source heat pumps because the ground is a more consistent temperature year-round than the air. If the ground loop is big enough, they will maintain efficiency more consistently through the seasons than air source heat pumps which means they can be more attractive for owner occupiers who have an interest in low running costs.
You can read more about how heat pump efficiency is calculated in our blog here.
The drawbacks of ground source heat pumps when compared to air source are space and cost. Ground source heat pumps need a ground loop or borehole array, which can be disruptive and expensive to install, and the unit itself is typically housed inside a building. Air source heat pumps can sit entirely outside the building and are cheaper to install.
Currently, ground source heat pumps only make up 9% of heat pumps in the UK but this figure is bound to grow, especially if shared ground arrays become commercially available.
At Clade we are source-agnostic when it comes to commercial heat pump installations. We do not believe one or the other is ‘better’ – it really comes down to the building specifications, environment, existing infrastructure and heating requirements of the customer.