Design of zero-carbon homes


Photo credit: Finnbarr Webster

How to build innovative, zero-carbon homes

Prefabricated steel modular building provider pioneers 100% operational renewable targets

The challenge

Rollalong Ltd specialises in prefabricated steel modular buildings and wanted to create more energy-efficient housing stock.
  • They asked Darren Evans to support them with the design of zero-carbon houses for three councils in the south of the UK.
  • They wanted these homes to be operationally net-zero so that over a year the properties would generate zero-rated energy bills.

The solution

  • Under the forthcoming changes to Part L 2020 building regulations, steel frame construction will not be able to use generic Psi values. This leaves two options: use default values under Part L, which are unlikely to pass, or use bespoke calculations.
  • We modelled the junctions and used bespoke Psi values to enable zero-carbon homes to be built.


  • Up to 100% improvement  in carbon emissions against building regulations
“Rollalong Ltd is a leader in zero-carbon home and is designing houses 30 years ahead of everyone else,” says Brandon Wipperfurth, senior sustainability and energy consultant at Darren Evans. “100% operational renewable targets are something people talk about as essential to meet 2050 net-zero targets. But as it’s so difficult and costly to do it keeps getting pushed back.”
“Our overall experience of working with Darren Evans has been very positive, the level of knowledge and additional guidance from Darren Evans team to achieve U-values, SAP calculations and thermal bridging details has been significant in the development of our product. “The team we dealt with were very professional and worked extremely well, communicating throughout the task and process. “We would not hesitate to work with Darren Evans again and see their input as an important part of achieving Rollalong’s future building standards that go beyond just meeting the minimum set by Building Regulations.”
Steve Chivers - managing director

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