13th January 2022

Continuous optimisation for Erda’s geo-exchange technology

The heating industry is quickly working to find the top low carbon solutions at a cost-effective price. Electricity is costly compared to gas, so the question that is repeatedly being asked is, how much does it cost these low carbon technologies to deliver heat?

To make heat pumps more cost effective, optimising system efficiency by reducing the amount of electricity used by the system is key.

Parasitic power, in this instance, is any power used by a system that is not directly used by making heat (consumed by heat pumps). It is the electrical energy required to move thermal energy around the system from one form to another. By reducing this parasitic power, we can increase our system CoP whilst driving down the cost to deliver heat.

At Erda we make continuous improvements to our geo-exchange systems – we are ALWAYS trying to reduce our electrical energy consumption and develop solutions that overcome industry problems. We have made many beneficial control changes over the years but one in particular led to significant pump energy savings.

The 3-port valve, our current system control, is widely viewed as a roadblock when it comes to controlling pump speed. To get around this, we used a demand approach and adjusted the flow rates accordingly based on the stores thermal demand. This allowed for better pump control and power reduction, without any drop off in thermal comfort.

Over the year we saw a 45% reduction in pumping energy used compared to the previous year and a 78% reduction compared to early operating years. This yielded an annual savings of £800 and 1.24 Tonnes of carbon (compared to the previous year). The figures below summarise these savings when compared to a best-case year.

These annual savings may seem modest, but Erda take a long-term view and over the remaining lifespan (17 years) of a system they can become significant.

As system CoP and parasitic power are important metrics to look at, another indicative KPI is thermal delivered / pumping kWh used. Following our pump control change, we noticed an increase to the amount of thermal delivered for every 1 kWh of pumping energy used. Competitors in the industry use 1 kWh of pumping energy to deliver an average of 50-100 kWh of thermal energy whilst Erda’s geo-exchange systems delivered more than twice that with the same amount of pump energy (following the control upgrade), using 1 kWh of pumping energy to deliver about 200 kWhT/kWh pump energy for the year.

By making other areas of the system more efficient, as well as the heat pumps, we are working to close the gap between system CoP and heat pump CoP… (another widely discussed topic in the industry) which leads to savings in all areas, cost, carbon, and energy.


Rachel Feeney
Erda Energy Manager

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