St George’s College Weybridge operates a complex campus of buildings ranging from state-of-the-art teaching facilities to structures hundreds of years old. The College wanted to replace the existing gas-fired heating installation serving its core buildings, reduce long-term energy costs and carbon emissions, and create infrastructure capable of supporting future development.
ReEnergise developed the ground source heat pump project from initial concept through business-case modelling, design, tendering, project and site management, Renewable Heat Incentive (RHI) accreditation and subsequent optimisation.
The project had to be delivered across a live College campus and within a demanding RHI timetable. COVID-19 initially caused the project to be paused, while later changes to the RHI reduced the proportion of capital cost expected to be recovered. Once the College decided to proceed, the team also had to manage difficult ground conditions, severe winter weather, global equipment shortages and the challenge of fitting major new plant into an existing plant room. Initial investigations indicated that 90 boreholes at 195 metres would be required. During drilling, the achievable depth proved to be approximately 140 metres and thermal response testing showed that additional boreholes would be needed. The ground array therefore had to be redesigned and extended without losing control of the programme.
The original business case showed the project could be broadly self-funding through the RHI. When the tariff fell, ReEnergise remodelled the case and confirmed that around half the project cost would be recovered. The College proceeded for the long-term operational and carbon benefits, with ReEnergise securing accreditation.
ReEnergise modelled and designed a system using four 222kW ground source heat pumps installed in the existing plant room. The revised ground array comprised 132 vertical boreholes at approximately 140 metres, serving four existing buildings and connecting a further three buildings across the College’s core.
Distribution valves and controls were upgraded to create a demand-led, climate-controlled system. When the College later planned a new teaching block, ReEnergise remodelled the system to confirm the available heating capacity and conceived and designed the addition of passive cooling using the ground array.
“Without the patience, clarity and expertise of ReEnergise we would not be saving the money we are or have as comfortable an environment as we do. Money well spent.”
Greg Cole
Bursar, St George’s College, Weybridge