WS Hewitson Ltd

Ground Source Heat Pump

The Situation.

Taking over the business, the owner wanted a growth strategy with better eco-credentials. Researching the broiler industry, it was identified that this showed a year no year growth of 10% and also allowed for lower environmental impact than the larger animal stock, especially ruminants.

To cover 100,000 chickens housed in three sheds, the owner installed a 800kW ground source heat pump (GSHP) and 120kW solar array to reduce carbon emissions from heating and chilling using fossil fuels, however, the heat pump never worked as it should, nor provided the savings it promised.

The client desperately needed a more efficient system as they planned to expand to a fourth shed and the coefficient of performance (COP) of the heat pump was just 2.5, under Ofgem standards.

The Solution.

Calibrate stepped in to assess the under-performing system that had been installed by another installation company who were unable to find a solution. Calibrate proposed a 5-step improvement plan.

Step 1

Calibrate Analytics, an energy assessment platform, was connected to Hauxley’s heat pump system allowing the team to diagnose problems to be fixed and also to resolve by re-

engineering so that the efficiency could improve to the levels expected from the business’s decarbonisation plans. This analysis highlighted a variety of improvements and ROIs

Step 2

Perform initial efficiency improvements through balancing of heating network and pump control. Calibrate set about removing the existing trend control system, implementing

a bespoke control strategy within the software to control the heat pump and make it more effective by taking the remote signals from the fans. Adding 8 additional temperature sensors meant that the system could be monitored to improve the running of the heat pump system and increasing the COP to Ofgem standards in order to claim the RHI tariff.

Step 3

Installed 500kW heat recovery to:

  1. maximise the efficiency of the system to save money
  2. Capture waste energy and re-use it providing an overall improved outlook of carbon emissions for the farm
  3. Allow for the research and development of reducing ammonia emissions for free to improve the sites environmental standards.

Step 4

Extended the heating element of the GSHP to provide heat for an additional 4th shed.

Step 5

Joined existing clients on the Calibrate service and maintenance plan.

The Outcome.

The project is now at step 3 of the accepted 5-step plan and the client has seen an increase in efficiency from 2.5 up to 3.8. Keeping the Calibrate Analytics System as a control system as well as an assessment tool, means that the monitoring for efficiencies is a constant as it allows access to real-time data to simulate improvements to the system for a continuously maximised system profile.

The client has the option to run his chicken sheds using 100% renewable inputs for 80% of the year up from 40%. Carbon output has been reduced by 34% based on increasing heat pump efficiencies and 73% against equivalent gas heating option. The pioneering agri-business has swiftly grown its poultry transition up to 100,000 birds and has gone from start up to sector leader due to a pioneering approach to transforming and diversifying operations.

Project Details




WS Hewitson Ltd


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