How efficient are ground source heat pumps? 

Edward Levien, commercial director at isoenergy spoke with our content editor, Natalie Persoglio, about the multitude of renewable technologies available to help society ‘go green’. Here we talk about the efficiency of ground source heat pumps… 

Our content editor spoke with isoenergy’s Edward Levien about the efficiency of ground source heat pumps. Here’s what he had to say...

“There are many renewable technologies that can be used to green your home or business, like solar panels. However, the most impactful change you can make is by replacing the old, inefficient fossil fuel heating system with a heat pump system.

“Heat pumps can replace boilers by using the naturally occurring heat from the earth instead of harmful fossil fuels like oil and gas. In the case of an air source heat pump, the heat is drawn from the air. A ground source uses heat from the ground or a water source. Both technologies only require electricity to power them.”

How does efficiency impact the number of carbon emissions produced? 

“Efficiency relates to how well something can be done, using the minimum input of energy to gain the maximum return. This is known as the Coefficient of Performance (CoP), which is used to demonstrate the amount of energy gained vs energy used. Gas boilers operate at an efficiency of around 90%, meaning that for every 1 unit of energy that is put in, there is a return of 0.9.

“When compared to a heat pump, that return is quadrupled with its 400% efficiency, meaning for everyone one unit of energy that is put in, an extra three is gained from the ground. This highlights how inefficient gas boilers are, but because of the cheaper upfront price, they are still widely chosen over a heat pump. Even though the heat pump is cheaper to run, and much better for the environment. 

“As a result, this increased CoP of three means the heat pump is using less energy to create the same amount of heating, significantly reducing the carbon emissions produced. Not to mention the fact that gas and oil boilers run on fossil fuels which create tons of carbon emissions. Heat pumps run on pure electricity, which is increasingly being produced renewably as the UK employs larger renewable energy generation projects like wind farms.”

How does efficiency save money on monthly heating bills? 

“As previously mentioned, the high CoP of a heat pump reduces running costs due to the heat pump requiring less energy input to produce the same amount of output. Even though there is a higher electrical demand, the CoP makes the electricity cheaper than fossil fuels and electricity can be generated at home by installing solar panels. 

“Owners of oil-fired boilers will be feeling the impact of fossil fuel heating as oil prices have been rising and fluctuating daily. Fossil fuel prices are also much higher, with recent increases doubling to over $120 per barrel of oil, surpassing the previous high in 2008. 

“The upfront cost of changing to a heat pump system can be a big barrier to changing to a green home. To help with this, the government currently has a grant called the Boiler Upgrade Scheme (BUS) that pays a one-off payment of £6,000 to those who are installing a ground source heat pump. 

Can you improve the heat pump efficiency? 

“When looking at the installation of a heat pump, the main thing that will improve the efficiency of a heat pump is the design of the system itself. 

“A poorly designed system can reduce the efficiency of a system through flaws in the pipework, groundworks, or heat pump. For example, ground arrays that are too close together or have too much pipework in one trench can see a reduced efficiency and potentially freeze the ground and pipes. 

“Heat pumps also must be sized right, if the heat pump is oversized then it will cycle too quickly, reducing efficiency and ultimately costing more to run. Cycling the heat pump quickly can cause damage to the compressor, reducing the life expectancy of your heat pump. With the right design of groundworks, plumbing, electrics, and installation of the right sized heat pump, there will be a visible difference in the efficiency of the heat pump. 

“There are also external factors that can contribute to improving the efficiency of a heat pump. The most effective method to increase the efficiency of a heat pump is through high-insulation standards. A well-insulated building will retain heat and cooled air better, if walls are thin with cavities, then air will slowly escape meaning the heat pump will have to work harder and longer to achieve a consistent temperature throughout the desired areas. 

“The current heating distribution system should also be considered as underfloor heating systems work very well with ground source heat pumps due to the larger surface areas being more compatible with lower flow temperatures. The lower the temperature, the more efficient the heat pump can run. Those systems with radiators will still work more efficiently than a gas boiler, but not quite as efficiently as with underfloor heating.”