“Which heat pump is better, air source or ground source?”

The best heat pump?

Many of my clients in Gloucestershire, Cheshire, Wales and beyond ask me “Which is best, an air source heat pump or a ground source heat pump?” The real question is “which system is better for you?”

There are many factors to consider when choosing a heat pump. Not only must the costs and efficiencies of each system be deliberated, but also the practicality of the installation, the available space in your property and planning restrictions.

The following table has been designed to succinctly demonstrate the different factors that my clients and I must consider when choosing the most appropriate heat pump for a project.

Comparing ground & air source heat pumps

ConsiderationsGround SourceAir Source
NoiseGround Source heat pumps use loops or coils of pipes laid under the ground and therefore do not make any noise. The heat pump itself, which is housed in a utility or plant room, does make some noise but no more than the average fridge.At Source Energy, we carefully choose heat pump models which produce no more noise than an average fridge and our Mitsubishi air source heat pumps have been awarded the Quiet Mark. We also position the heat pump away from bedrooms and neighbouring properties to eliminate noise disturbance.
Outdoor space requiredAs a guide, an 8kW Thermia ground source system would require around three ground loops, each at 200 metres in length. A minimum land area of 700 square metres would be necessary for loops of this size to be laid. For more information read this article from Izzy our South East heat pump Expert - How much space do you need for a ground source heat pump?Air source heat pumps do not require much outdoor space and do not need to be placed in a southward orientation. They must be situated 30cm from the property, with 1 metre of free space around the air handling unit.
Landscape & visualGround source loops are below the ground and therefore do not have any visual impact. You may need the consent from the council to prune or fell any trees protected by the Tree Preservation Order.Air source heat pumps may pose a visual impact on the property and the installation may require planning permission from your local planning authority. One way to conceal the system, without compromising efficiency, is to surround it with a terrace:
Air Source Heat Pump outdoor unit with screening View our air source heat pump gallery »
Traffic & transportAccess for drilling or excavation machinery must be considered for ground source.Accessibility for air source is less of a consideration as the installation is less invasive.
Efficiencies & Renewable Heat Incentive paymentsGround source systems do carry a greater initial investment but due to higher efficiencies, you can receive 80-100% of the installation cost paid back over the course of 7 years from the RHI.

The current payment tariff for ground source is 19.1p/kWh.
While air source systems carry a lower initial investment, there is a slight reduction in efficiency when comparing with ground source. A new build property could achieve a 4:1 efficiency with a ground source while air source would likely achieve a 3:1 efficiency.

The current payment tariff for air source is 7.42p/kWh.

If you have further questions about air source heat pumps, read our helpful article - 5 Air source heat pump questions answered »

Speak to the Wales & West England Heat Pump Expert by calling  0800 865 4328 for more advice about your project in Cheshire, Shropshire, Staffordshire, Warwickshire, Herefordshire, Gloucestershire, Worcestershire, Powys, Gwent, Glamorgan, Dyfed, Pembrokeshire, Gwynedd, Clwyd and beyond.

For more information about different heat pumps, visit these pages and watch the videos below: