Northumberland auction house, Hexham and Northern Marts, is set to make a 236% return on investment – reaping an estimated £862,000 in energy savings and commercial RHI payments over the next 20 years – after installing solar PV panels and a NIBE ground source heat pump system.

The auctioneer, which specialises in livestock, wanted to replace its old gas-fired heating system with a more sustainable alternative that would also earn income through the Renewable Heat Incentive (RHI).

Renewable energy specialist and NIBE VIP Installer Calibrate Energy Engineering were tasked with finding the right solution to meet the heating and hot water demands of the 112,050 sq ft building.

Calibrate specified, designed and installed a 300 kW renewable heating system made up of five 60 kW NIBE F1345 ground source heat pump (GSHP) units. They paired this with a 50 kW solar PV array, fitted to the roof of the main pen area, which partially powers the NIBE GSHP system. The in-ground heat collectors required for the GSHP were laid in the fields around the buildings, with the controls units sited in a prefabricated plant room to the rear of the premises.

The GSHP system generates enough renewable energy to heat the sales centre (including its reception area and three sales rings), while the solar PV array provides renewable electricity to complement it.

The installation took just three months from start to finish.

Docked together in a cascade for greater output capacity, the five NIBE F1345 GSHP units now meet 95% of Hexham and Northern Marts’ 394,000 kW/h annual heating and hot water demand. Meanwhile, the 50 kW solar PV array generates enough free electricity to offset a significant 50% of the power needed to run the GSHP system.