With the government aiming to build 1.5 million homes during this parliament, the pressure is on for builders and developers to deliver housing quickly while also meeting tougher performance expectations. The Future Homes Standard (FHS) will put a building’s fabric performance under far greater scrutiny, meaning the right specification decisions at merchant level will play a vital role in delivering compliant, energy efficient homes. Getting the building fabric right from the outset by paying careful attention to detailing and thermal bridging can prevent some of the issues that create inefficient homes. Simon Wright, Technical Manager at Keystone Lintels explores what FHS means in practice, the importance of the fabric first approach to design, and how a one piece thermally-efficient lintel can significantly improve SAP ratings while reducing dependence on costly renewable technologies.
While the uplift to Part L of the Building Regulations has already pushed higher performance standards, the publication of the Future Homes Standard in 2026 will ramp up expectations significantly for new housing. The June 2022 update required a 31% reduction in carbon emissions for all new homes but the changes under the FHS will mean that new housing needs to achieve a 75-80% emissions reduction. This means that fabric performance will play a critical role in hitting these targets and delivering homes that generally perform.
Prioritising the building fabric
Despite the FHS requiring the use of solar panels and heat pumps, these technologies alone will not be enough. Constructing an airtight, well-insulated building fabric that minimises heat loss will be key to hitting energy and emissions targets and achieving compliance, whether for large developments or individual houses.
Improving the thermal efficiency of the building envelope provides more than just low emissions, it also provides occupants with superior thermal comfort and air quality, creating comfortable indoor spaces that enhance productivity, health, and wellbeing.
Tackling heat loss
For many builders, one of the biggest challenges of the fabric-first approach is tackling thermal bridging, which can account for up to 30% of a home’s heat loss if not managed correctly. Eliminating thermal bridging through intelligent design and correct product specification will be vital to meeting these new regulations.
However, as an industry what is designed and what is built on site does not always align due to substituted products or detailing. Workmanship and site skills can cause issues, triggering a performance gap between as-designed and as-built building performance. Weak spots significantly impact heat loss and overall fabric performance.
The Building Regulations Part L report (BREL) details materials that must be installed without substitution, unless recreated or amended by an energy assessor. Building control can use this report as a checklist and may ask for recalculations if different brands or material types with different thermal values are used.
Under the updated regulations, builders must now work with actual thermal transmittance values for building products within the building envelope; in the past, generic ACD (accredited construction detail) values were accepted within the SAP assessment. This change ensures the Y value obtained is accurately represented within the BREL report.
The role of site evidence
New photographic evidence requirements also mean that builders need to demonstrate clearly that key junctions have been constructed exactly as designed. This will need to have geo-location technology, and the report will be provided to building control and the building owner. Proof must be provided that the dwelling has been constructed with the same materials as designed, ensuring it performs as efficiently as intended.
High-performance lintels
Traditional steel lintels are known to create thermal bridges in homes due to steel’s high thermal conductivity and long spans. However, solutions such as Hi-therm+ address this, setting a new standard for thermal efficiency in steel lintels. By incorporating a thermal break, Hi-therm+ is up to five times more thermally efficient than standard lintels, providing a cost-effective solution that saves energy over a home’s lifespan when the fabric is done right.
A recent enhancement to the Hi-therm+ Lintel is pre-fitted insulation which includes a higher content of recycled materials, further boosting thermal efficiency. With up to 20% increase in performance, Hi-therm+ Lintels can improve overall junction Psi values by up to 15%, making them an ideal choice for a fabric-first approach to meeting modern regulations. This makes Hi-therm+ the go-to solution for contractors and housebuilders seeking high-performance, sustainable products that comply with current standards.
These lintels have significantly impacted home thermal efficiency and are specified on many housebuilder projects around the UK due to low cost and improved performance in lowering carbon emissions within the Standard Assessment Procedure (SAP). Lintel performance should not be understated, particularly given the role they play in achieving optimal thermal performance.
Balancing ambitious housebuilding targets with stricter performance requirements will mean that contractors must get specification decisions right from the outset. Taking a fabric-first approach is not simply about compliance it will be key to building homes that are energy efficient and add value for the long term.
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