Many businesses in the fenestration supply chain assume the Future Homes Standard is primarily about achieving lower U-values. In reality, the most significant change in the new Approved Document L:2026 is that U-values for new-build dwellings will need to reflect the actual size and configuration of each window and door installed.
This represents a major departure from the standard benchmark calculations commonly used today.
What must now be included?
Under the new approach, calculations will need to account for:
- Actual opening dimensions.
- Product-specific configurations.
- Sills.
- Frame extensions.
- Dummy sashes.
- Dummy transoms.
- Mullions and rails.
- Georgian bars.
In short, every opening becomes a bespoke thermal calculation.
The challenge for manufacturers
A typical new home may contain, on average, around eight windows and two doors. Based on recent housing completion figures, this could translate into more than a million bespoke window calculations every year.
Producing calculations manually at this scale is simply not realistic.
Technology will be essential
The webinar highlighted that software, automation and digital workflows will become critical. Existing calculation tools may need updating to accommodate the additional components now required within U-value specifications.
Businesses supplying the new-build sector should already be evaluating:
- ERP integrations.
- Dedicated U-value calculators.
- Third-party calculation platforms.
- Data management processes.
A competitive opportunity
While the changes create new challenges, they also create opportunities for businesses that can deliver accurate, reliable and scalable thermal performance data. House builders and SAP assessors will increasingly depend on trusted information throughout the design and compliance process.
