A recent report from the Future Homes Hub offers valuable guidance for homebuilders and designers looking to build better and more sustainably with system comparisons at the centre of its findings.
As all those involved in construction work toward meeting Future Homes Standard (FHS) targets, there’s growing recognition that reducing carbon emissions means looking beyond just operational efficiency to embodied carbon.
‘Embodied and Whole Life Carbon in Future Homes Standard Options’, explores how various housing designs under consideration for the FHS impact both embodied carbon (from materials and construction) and operational carbon (from energy use) – together known as whole life carbon. By comparing typical house types, the report underscores the importance of taking a holistic view and the need for ‘tailored assessments’, warning that focusing solely on the structural wall materials oversimplifies a much broader issue.
Following the launch of the FHS consultation in December 2023, developers have been working to identify cost-effective, scalable specifications that comply with Part L (focused on operational carbon). To support this effort, the Hub brought together a working group of developers and carbon specialists, who examined three common fabric and service specification options. Each was evaluated for its embodied and whole life carbon impact.
Embodied carbon was calculated using One Click LCA – a widely used commercial software tool among housing developers for carrying out Whole Life Carbon Assessments – while operational carbon was assessed using SAP 10.2, in line with Building Regulations Part L 2021.
The three fabric and services specification options were ‘defined through discussions with the working group members to represent likely options for meeting the FHS.’
Option A: Masonry with 100mm cavity, mineral wool insulation, triple-glazed uPVC windows
Option B: Masonry with 150mm cavity, mineral wool insulation, double-glazed uPVC windows
Option C: Timber frame with 140mm studs, mineral wool insulation, 25mm PIR over-boarding, double-glazed uPVC windows.
The findings show that timber frame construction generally has 3-5% lower upfront embodied carbon intensity and 1-2% lower whole life carbon intensity than masonry options with comparable thermal energy performance. However, overall carbon impacts across the options were broadly similar, reinforcing the message that no single solution significantly outperforms the others in terms of embodied carbon. In other words, as outlined in the findings there is no ‘silver bullet’ when it comes to reducing embodied carbon of new homes.
One encouraging insight is that the Hub’s Future Homes Carbon Assessment Tool – which uses a simplified elemental method – showed strong alignment with One Click LCA for fabric-related aspects. This makes it a practical starting point for smaller developers or those lacking the resources for detailed modelling.
“Understanding whole life carbon is a crucial next step if we are to meet our net zero carbon ambitions as a sector,” says Adam Graveley, Head of Technical and Innovation for the Hub. “At this natural time of change, as homebuilders and designers update their house types to meet the Future Homes Standard, there is an opportunity to also consider the up front and life cycle impact of embodied carbon.
“This report supports those developers who are asking the next question: How do we build homes that both meet the Part L regulations and reduce the embodied carbon impact to support the transition to net zero? We encourage developers to utilise the insights from this report and engage with our Whole Life Carbon Assessment Tool to further refine their designs.”
The FHS represents one of the most significant regulatory shifts for UK housing in decades. New materials and construction methods – and in many cases very demanding approaches – will hopefully create better low-carbon, energy-efficient new homes. Timber has the edge when it comes to embodied carbon, but everything rests on providing better fabric energy performance. Choosing between timber or masonry construction isn’t just a matter of tradition or cost – it’s now a strategic sustainability decision that will reshape how developers design, specify, and construct 21st century homes.
