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The Future Homes and Buildings Standard Consultation proposed methodology for sleeving low carbon plant on heating networks uses peak demand for sizing of plant.  This will have a significant impact on developers, potentially accelerating the rate of heat network decarbonisation compared to a methodology using annual heat demands, but it will result in larger plant and associated impact on utilities, higher capital costs and potentially higher running costs for customers.

This is a fundamental shift from the use of annual energy demands for plant sizing, which was what was implicitly referred to in 2022 guidance.  This means that, in order to achieve the same contribution, and hence carbon performance, a low carbon source sized on the basis of peak demand will require much greater installed capacity than a system sized on the basis of energy.

There can be many consequences to this:

  • Higher capex, opex and repex, which translates into higher resident’s charges;
  • Greater spatial, structural and utility requirements;
  • Potential reduction of the contribution of revenue-generating plant, such as CHP (where already present), affecting residents heat charges;
  • Surplus capacity, resulting in low run time per unit.

At this stage it is unclear how or if good practice solutions such as relying on thermal stores can be incorporated into the sizing methodology.

We are seeking further clarity on this subtle but far-reaching change as it will impact many heat networks which are part-way through development in the coming years.