Ground Source Heat Pump Comparisons

Trying to find the best heating system for your property? Thanks to the efficiency of ground source heat pumps, running costs can be reduced by as much as 30 – 50% compared to fossil fuels. See how they compare to other heating systems:

•  Air source vs. ground source heat pumps

•  Oil & LPG boilers vs. ground source

•  Geothermal heating vs. ground source

•  Biomass vs. ground source

Kensa Ground Source Heat Pumps Diagram for Self Builds and Renovations with Renewable Heat Incentive

What is the best heating system?

Ground source heating

A ground source heat pump delivers the best low-carbon heating. It’s an affordable and eco-friendly alternative to fossil fuels such as gas, oil and LPG, which typically contribute to carbon emissions, air pollution and ultimately, play a part in climate change and global warming.

Achieving a net-zero carbon future

Heating and hot water make up 25% of total energy use in British homes, equating to 15% of our greenhouse gas emissions.¹ To reduce the UK’s carbon emissions, the best heating systems are being encouraged by the government.

This starts with the ban of fossil-fuel heating in domestic new-build properties from 2025 – forming a part of the government’s plans to achieve net-zero by 2050. Gas and oil boilers are some of the fossil fuel systems that the government is banning from 2025.

What is a heat pump?

In brief, a ground source heat pump will:

See how a heat pump works

What are the advantages of ground source heat pumps?

The advantages of ground source heat pumps vs. other heating systems include:

  • One of the lowest in carbon and running costs
  • Can be used to provide passive and active cooling
  • No planning permission required
  • Quiet operation
  • Safe and easy to operate
  • Simple to install
  • No noxious gasses or risk of combustion
  • No point-of-use emissions such as Nitrogen Oxide (NOx), Sulphur Oxide (SOx) or Carbon Dioxide (CO²).

Having a ground source heat pump means the property is much more energy efficient and less reliant on fossil fuels.

Alistair Mackintosh, Selfbuilder

Air source heat pumps vs. ground source heat pumps

Although both air source and ground source heat pumps are renewable alternatives to fossil fuels, they hugely differ in efficiency, running costs, carbon savings and durability.

Unlike air source heat pumps, the inherent efficiency of ground source heat pumps means they can deliver the lowest running costs of any type of heating system and the best return from the RHI – giving you payback on your investment typically in 5 or 6 years.

See our air source vs ground source page

Oil & LPG boilers vs. ground source heat pumps

Oil and liquefied petroleum gas (LPG) is traditionally the go-to alternative fuel for buildings that are not connected to mains gas. However, prices of oil continue to fluctuate against a backdrop of growing global concerns – particularly energy security.

Meanwhile, heat pump technology has evolved, along with guaranteed RHI income and affordable running costs. Ground source heat pumps have therefore become a more viable and preferred option for off-gas areas.

Add to this the pressure of government plans to ban fossil-fuel heating systems in new builds from 2025, and it looks like oil and LPG boilers could be phased out entirely by 2050.

Disadvantages of oil & LPG boilers

  • Vulnerable to energy price hikes and fluctuations
  • Bulky and unsightly fuel storage tank
  • Highly flammable
  • Reliance on fuel deliveries
  • Possibility of fuel theft
  • Pay for the energy upfront all in one go
  • Complicated installation
  • Contributes to air pollution through the emission of particulates, Nitrogen Oxide (NOx) & Sulphur Oxide (SOx)
  • High carbon content.

Unsightly tank

Running costs of oil boilers vs. ground source

Oil boilers

There are a number of factors that make oil prices volatile. The price of crude oil is particularly sensitive to the laws of supply and demand, which can vary worldwide with fluctuations in the economy, political unrest and extreme weather events.

Supply can be influenced by the Organisation of Petroleum Exporting Countries (OPEC), who will cut output in order to strengthen prices by reducing supply.

Ground source

Ground source heat pumps can save occupants around 30 – 50% in running costs compared to oil boilers. Electricity prices, as used to drive a ground source heat pump, do not suffer from the same volatile prices.

Aside from a ground source heat pump’s inherent efficiency, delivering typically 3 to 4kW of free heat energy for 1kW of electrical energy and making the use of off-peak tariffs in well-insulated buildings, the running costs of ground source heat pumps are significantly lower than oil boilers.

That, plus an income from the RHI, is a benefit you wouldn’t see from oil.

Combating fuel poverty & oil in off-gas areas

The savings on our energy bills compared with oil is fantastic and our house value has increased as a result of the installation - we’re over the moon!

Stephen Chidgey, Homeowner

Maintenance of oil boilers vs. ground source

Oil boilers

Oil boilers use combustion in the heating process, so they must be serviced and maintained correctly. Failure to do this can lead to major health risks, such as the production of poisonous gases like carbon monoxide.

Ground source

As ground source heat pumps do not use combustion, there is no risk of poisonous gases being emitted.

Moving parts are kept to a minimum and are non-serviceable, so maintenance is minimal. This makes ground source heat pumps significantly cheaper to maintain, saving occupants or ground source owners money by eliminating the need for annual servicing.

Lifetime of oil boilers vs. ground source

Oil boilers

These days most oil boilers are condensing boilers, as they provide a much higher efficiency than non-condensing boilers. Oil-fired condensing boilers typically have a shorter life (7 to 10 years) than traditional non-condensing boilers, as the heat exchangers can rot out quickly due to the acidic condensate.

Ground source

Ground source heat pumps generally have a design life of approximately 20 years due to their lack of moving parts and secure installation inside the home.

Storage of oil vs. ground source

Oil

Oil supply for oil boilers must be stored on site. It’s generally stored in a bunded oil tank, which is basically a small tank within a large tank. The larger tank is able to hold 110% of the capacity of the smaller tank. This is used to protect the surroundings of the tank from any oil spills of leakages. When storing oil, there needs to be sufficient space and access to the tank.

With OFTEC health and safety regulations stating that it must be located within 1.8m of the building, the unsightly oil tank can take away from the aesthetics of a property. As well as that, security measures against theft need to be considered if large volumes of oil are being stored on site.

Ground source

As ground source heat pumps run on electricity, no fuel storage or deliveries are required on site – allowing for additional space, peace of mind, and preventing the need for storage that many people feel is an eye sore.

Carbon emissions of oil boilers vs. ground source

Using the carbon intensity factors proposed for SAP 10, an oil boiler emits almost five times as much carbon as a ground source heat pump.

In terms of carbon emissions, there is no justification for the use of oil or LPG boilers when far more appealing and renewable heating options are available. This is why the government is phasing out oil boilers in favour of lower carbon renewable heating systems such as ground source heat pumps.

Can a heat pump replace an oil boiler?

Yes. For older properties that are not especially well insulated, Kensa will help you to establish whether the existing heating system and existing insulation levels will be compatible with a ground source heat pump, or if your heating distribution system and energy efficiency measures require any upgrades.

If you are undecided on whether you should upgrade your radiators or insulation levels, you can run a trial over a heating season. To do this, we recommend you turn down the flow temperature of your existing boiler to 50°C and run the system through the winter heating season to mimic the output of a ground source heat pump system.

If you find you can maintain your required comfort conditions at this lower flow temperature, then you have proved that your existing heating distribution system and the current heat loss of your property is compatible with a ground source heat pump installation – without any upgrades required. If you were not satisfied with the comfort levels then we advise you to upgrade your radiators, and improve the insulation levels in the property prior to installing a ground source heat pump.

Submit your plans for advice

Geothermal heating vs. ground source heat pumps

What is the difference between ground source heat pumps & geothermal heating?

There is often much confusion when it comes to comparing ground source heat pumps to geothermal heating. Some people use the terms interchangeably, but there are key differences:

  • Geothermal heating uses heat directly from the earth’s core, such as hot springs, geysers and volcanic hot spots.
  • Ground source heat pumps absorb the sun’s energy stored in relatively shallow ground and upgrade this for use in domestic and commercial applications.

Ground source heat pumps, like those manufactured by Kensa Heat Pumps, generally take heat from 1.2m – 200m depths. In this zone, there is a large amount of low-grade energy available, which needs a heat pump to upgrade this to more useful temperatures.

The reason geothermal heating is often confused with ground source heating is that both ultimately harness heat energy from the ground to provide heating and hot water to buildings.

However, the main differences are where the heat originates and the application the heat will be used for.

What is geothermal heating & how does it work?

Geothermal heat comes from the earth’s core; ‘geothermal’ literally means ‘earth’s heat’. It uses heat directly from drilling deep or shallow sources emanating from the earth’s core, such as hot springs, geysers and volcanic hot spots.

Borehole drilling for geothermal heating can often be drilled to depths many kilometers below the ground. In the UK, you have to go down 500m – 2500m before there is any appreciable input from the earth’s core. Geothermal typically needs to be deployed at large scales to make it financially viable.

Geothermal systems operate at temperatures of 120°C – 300°C and therefore do not necessarily need a heat pump to upgrade the heat, nor a ground loop system.

Large-scale plants and communities tend to use geothermal energy over ground source heat pumps.

Ground source heat pumps vs geothermal heating - A geothermal power plant

Why does the difference between geothermal & ground source matter?

When you drill a deep geothermal hole, it’s not always clear what the conditions will be like further down. Inevitably, this could determine how well the system will work.

However, ground source heat pumps absorb energy at shallower depths, which means there is a much higher level of certainty around the conditions you will find.

What are the other common names for ground source heat pumps?

The following terms are sometimes used when referring to ground source heat pump installations, and can be misleading and technically inaccurate due to their ‘geothermal’ references:

  • Geothermal heat pumps
  • GeoExchange heat pumps
  • Earth-coupled heat pumps.

Other less commonly used terms for geothermal heating include:

  • Deep geothermal
  • Enhanced geothermal systems
  • Geothermal, direct use
  • Hydrothermal
  • Hot rocks
  • Hot dry rocks
  • Geothermal power.

Biomass vs. ground source heat pumps

Disadvantages of biomass heating compared to ground source heat pumps:

  • Space required for fuel storage
  • Reliance on regular fuel deliveries
  • High maintenance compared to ground source heat pumps
  • Planning permission required due to emissions
  • Contributes to air pollution through the emission of particulates, Nitrogen Oxide (NOx) & Sulphur Oxide (SOx).

References

  1. UK housing: Fit for the future? Committee on Climate Change, 2019