♻️ Design Compliance: The Part L/F/O Upheaval

Wednesday 15th June 2022

The Fabric First Future – New Building Regulations Make Homes 31% More Efficient (and Complex)

The new Building Regulations (specifically Parts L, F, and the new Part O) came into force on June 15, 2022, as an interim step towards the Future Homes Standard (FHS) of 2025. These changes mandated a 31% reduction in CO2 emissions for new dwellings compared to the previous standards.

This was perhaps the biggest operational challenge of the period, requiring fundamental changes to how we design and build. This was a direct, statutory response to the government's Net Zero strategy (Headline 5).

Part L (Energy): The key change here was the introduction of much tighter U-value requirements (better insulation) and the requirement for 100% airtightness testing on every single new dwelling (no more sample testing). This adds cost, requires far more precise work on site, and increases the time spent on detailing the building envelope.

Part F (Ventilation): As homes become tighter, controlled ventilation is critical. The new Part F tightened standards and mandated specific mechanical systems (like MVHR) in highly airtight buildings to prevent damp and condensation.

Part O (Overheating): This was a brand-new regulation introduced to mitigate the risk of summer overheating in highly insulated, airtight homes. It added complexity to glazing specification and orientation, and sometimes required external shading or cooling systems.

Our Opinion: We support higher standards—it leads to better, more sustainable homes. However, the requirement to adapt instantly meant a sharp learning curve and new costs: paying for certified airtightness testing on every unit, training staff on new ventilation systems, and managing the inevitable pushback from designers who suddenly had to redesign projects that had received planning permission under the old rules.

Debate Point: Did the transitional arrangement (allowing projects submitted before June 2022 to start up to June 2023 under the old rules) create a "cliff-edge" that resulted in a last-minute, less-efficient rush to start work under the old, lower standards?