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, gas and oil.
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.
Both air source and ground source heat pumps are efficient, low-carbon alternatives to traditional fossil fuel heating systems. The difference lies in their heat source: air source heat pumps use the outside air, while ground source heat pumps draw energy from the ground.
Because ground temperatures remain consistent throughout the year, ground source heat pumps deliver higher efficiencies, lower running costs and more reliable performance, particularly during colder weather when heating demand is highest.
As gas is a fossil fuel, it releases carbon dioxide (CO2) – a greenhouse gas that contributes to climate change. To achieve the UK’s legally binding target of net-zero carbon emissions by 2050, it’s vital that fossil fuels, including natural gas, are phased out and replaced with renewable alternatives. Delivering a whopping 77% saving on emissions versus gas, see how ground source heating compares to the familiar boiler.
Oil and liquefied petroleum gas (LPG) is traditionally the go-to alternative fuel for rural 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.
Oil and LPG boilers have a variety of disadvantages: energy price fluctuations, reliance on fuel suppliers and deliveries, large bulk payments, flammable fuels, complicated installation, air pollution and unsightly storage tanks.
Meanwhile, heat pump technology has evolved, along with accessible funding streams and affordable running costs. Ground source heat pumps have therefore become a more viable and preferred option for off-gas areas.
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 around 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.
Ground source heat pumps are also significantly cheaper to maintain, saving occupants or ground source owners money by eliminating the need for annual servicing. Combined with their long lifespan, ground source heat pumps have a much lower lifetime cost.
Additionally, 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.
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 is often confused with ground source heating and tends to be used interchangeably. The reason being both harness heat energy from the ground to provide heating and hot water to buildings.
Geothermal uses heat directly 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.
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.
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 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.
As ground source heat pumps absorb energy at shallower depths there is a much higher level of certainty around the conditions you will find.
Some people have proposed switching from gas to hydrogen, but in reality it’s not easy or straightforward to convert the gas network to hydrogen and there is no proven blueprint for this solution.
What happens in the next decade could be the measure of success or failure in achieving net-zero carbon. The longer we wait for hydrogen to create a solid solution, the closer we are to the tipping point.
Ground source has greater potential to decarbonise heating and; even better, it is tried and tested and ready to deploy right now.
A hybrid heat pump system, also known as a dual fuel system, couples renewable energy with fossil fuels to provide heating and hot water to a home. A hybrid can be made up of a heat pump and a fossil fuel heating system, but in this context, we’ll look at how a hybrid – made up of an air source heat pump component and a gas boiler component – compares to a single ground source heat pump system.
A hybrid heat pump system is designed to meet the building’s heating and hot water requirements, whilst reducing carbon emissions through the use of renewables. It involves the installation of both the fossil fuel heating system component and the heat pump component.
If you would like a hybrid system and you already have a gas boiler installed, that could mean you only have to account for the cost of the air source component. If you were to install both components together from scratch, the total cost of a hybrid domestic heating boiler with its associated air source heat pump can be between £7,500 to £15,000. However, this will vary depending on the type of project and heating requirements.
Fuel costs will be somewhere between the costs of a gas boiler and an air source heat pump (depending on the operating split). However, some of the other operating costs are doubled up. For example, you end up paying two standing charges – one for electricity and one for gas. You also need annual servicing and regular maintenance to check that the gas boiler is combusting fuel safely.
One of the main issues with a hybrid system is that it will incur twice the replacement costs of relatively short-lived appliances typically every 10-15 years for both appliances.
The initial cost of a pure ground source heat pump conversion from mains gas is currently more expensive than an air source heat pump/gas hybrid. However, the ground array infrastructure has lifetimes in excess of 100 years and because ground source heat pumps are typically located indoors they have longer lifetimes of 20-25 years.
Once you model the costs over longer periods and account for fuel consumption, standing charges, servicing, maintenance and replacement costs then ground source heat pumps become the lowest cost option.
The long-lifetime, long-term savings and lack of maintenance that comes with a ground source heat pump soon make up for the initial cost, which is a significant advantage in the context of mass deployment.
In terms of emitting carbon emissions, a hybrid heat pump still has the disadvantage of burning fossil fuels. Although this is reduced by the heat pump component, it will still produce a higher percentage of emissions versus a single ground source heat pump system.
Biomass boilers and ground source heat pumps can both provide low-carbon heating, but ground source is typically simpler to live with long term. Biomass systems require space to store fuel, regular fuel deliveries and more ongoing maintenance, while combustion also produces air pollutants such as particulates and nitrogen oxides. Ground source heat pumps eliminate on-site combustion and fuel storage, require little ongoing maintenance, and provide a clean, discreet heating solution once installed.
