HEAT NETWORK | COMBERTON VILLAGE COLLEGE It will be a showcase for retrofitting renewable energy technologies and heat network installations to deliver long-term carbon emissions reductions incrementally later to supply other heat demands, constraints on plantroom space and space for new boreholes mean there is no capacity to extend the scheme beyond the college boundaries to serve local residents, for example. However, Cambridgeshire County Council, again working with Bouygues E&S, has built a low carbon heat network at nearby Swaffham Prior (see CIBSE Journal February 2022), which it may look to reproduce elsewhere in the county. The heat decarbonisation project at Comberton Village College started in October 2021 and the heat network has been running since January although the scheme has not yet reached practical completion. One of the things we have had to make clear to the college is the importance of the operational strategy, says McGrath. At the end of the year, when we do the energy reconciliation [see panel, Funding the decarbonisation of heat], if the scheme is using more energy than we anticipated we need to be able to understand whether this is related to design or an intervention from the colleges facilities management team. The pioneering project is expected to become a showcase for retrofitting renewable energy technologies and heat network installations to deliver significant long-term carbon emissions reductions and future lifecycle costs. While projects such as Comberton are novel now, they are set to become the new norm as colleges and local authorities continue to move away from fossil-fuelled combustion to heat their buildings. CJ FUNDING THE DECARBONISATION OF HEAT The only way a decarbonisation scheme like this could work financially is if there is funding available to support the capital cost of the work, says Tom McGrath, energy design manager at Bouygues E&S UK. The Comberton Village College project has been funded by a 1.9m government grant from Phase 2 of the Public Sector Decarbonisation Scheme (delivered by Salix Finance) and a 1.2m investment from Cambridgeshire County Council. The Cam Academy Trust, of which Comberton Village College is a member, has entered into a managed services agreement with Cambridgeshire County Council to fund plant not covered by grant funding. This arrangement allows the council to recover its capital investment while still delivering a net operational saving to the trust. For its part, Bouygues has to deliver an investment-grade proposal. This defines what the design and build contractor is going to deliver, and at what cost, and puts a figure on how much energy the scheme is expected to consume in use. Energy consumption will be monitored annually. There is a yearly reconciliation based on measuring and verifying the actual performance of the system. If the performance is within an acceptable variance, everyone is happy. If the scheme uses more energy than it is supposed to use, Bouygues is responsible for funding the overspend then this is either banked to cover any overspends, or used to pay back the project earlier. Were confident the project will deliver as expected, but with the guarantee, it de-risks the project for the client because, if it doesnt deliver what we said it would, then Bouygues will pick up the shortfall, says McGrath. Flexible and Efficient Nozzle Diffusers Stable and defined air distribution through set nozzle patterns Maximum induction, utilising the Coanda effect Quick mixture enabling adaptation to changing room conditions Adaptable and renovation-friendly via nozzle adjustment To learn more, visit www.swegon.com/uk/nozzles 28 August 2023 www.cibsejournal.com The project involved installing 140kWp of PVs on the roofs