The Future Homes and Buildings Standard (FHBS) represents one of the most significant attempts to align multiple aspects of building performance within the Building Regulations. However, does it go far enough? That’s the question being posed by Pete Hollingworth, managing director of wood fibre insulation manufacturer, STEICO, who argues that an even more holistic approach to building performance is needed.
Developed in response to the UK’s binding net zero targets, the FHBS recognises that the regulations are interdependent. It combines Part L – the conservation of fuel and power, Part F – Ventilation and Part O – Overheating. This means the effect of a change made to one document must be considered on the other two to ensure that performance is maximised and there are no unintended consequences.
While this creates a more aligned approach, gaps remain, even within these documents. For example, insulation materials that combine high density, high heat storage capacity, and low thermal conductivity can contribute to reducing the risk of summer overheating as part of the overall design approach. Characteristics such as thermal diffusivity and time delay can be calculated to measure performance in much the same way as a U-value. Yet there is no mention in Parts L or O on the role that building materials that add thermal mass can play in helping to reduce overheating.
Furthermore, to cover all factors contributing to low carbon buildings and focus on the health and wellbeing of the occupants, more performance factors should be included. To address these gaps, STEICO is calling for a new Approved Document – Part V.
Part V: Taking a holistic approach to building performance
Part V would cover important omissions from the FHBS such as Approved Document C, which relates to the control of moisture. Failure to control moisture correctly leads to mould growth, an issue which led to the creation of Awab’s law to protect the health of families in rented accommodation.
Buildings must be constructed to both prevent external moisture entering buildings and manage internal moisture. While the role of vapour control layers (VCLs) and breather membranes are widely acknowledged and understood, other construction materials also play a part. Diffusion open insulation, such as wood fibre insulation boards and batts, allows moisture to diffuse through the material, whereas other insulants are more diffusion resistant. How these different materials are incorporated within the building fabric can have an impact on how the building successfully manages moisture movement.
As well as using the right materials, the quality of installation of building materials is directly linked to performance. While the Approved Documents contain requirements and references relating to workmanship and compliance, there is limited practical guidance illustrating what good installation looks like on site. Incorporating guidance in multiple easy-to-access forms such as written, photographic and video, would ensure a joined-up approach to minimum standards.
Clamping down on embodied carbon
In England, the Building Regulations currently address operational carbon—the emissions associated with the energy used to power, heat and light buildings—through Part L, but do not regulate embodied carbon. The omission of embodied carbon from construction materials, which equates to around 10% of the UK’s total greenhouse gas emissions (roughly 64 million tonnes of CO₂eq annually), has been highlighted by industry leaders who proposed the introduction of Part Z. Despite this, and the proposal of a private members bill to introduce embodied targets in the UK, they remain voluntary.
With the 2050 deadline looming, this must be rectified and quickly. Incorporating embodied carbon alongside operational carbon would give an accurate whole life assessment of every building, not just those working under a sustainability certification system. This would encourage product manufacturers to look for ways to reduce their carbon impact and speed up progress towards a net zero carbon-built environment.
Creating healthy buildings
What makes a healthy building has long been debated in specification circles. Part V would recognise that it’s not the buildings themselves that are healthy, but the Indoor Environmental Quality (IEQ). This measure would go beyond the better-known Indoor Air Quality (IAQ) to consider other factors including thermal comfort, lighting and acoustics. These IEQ parameters are specified in both BS EN 16798-1:2019 TC and Table 10 of a European Commission document ‘Technical building systems, indoor environmental quality and inspections.
The APPG (All Party Parliamentary Group) for Healthy Homes and Buildings estimates that poor quality housing costs the NHS £1.4 billion per year. While the majority of affected homes are unlikely to be new builds, introducing an IEQ standard could help support the delivery of healthier indoor environments within new homes.
Ultimately, decisions made to enhance and improve the building fabric in one area can directly affect performance in another. Part V would bring these considerations together, creating a more holistic framework for building performance. Rather than treating energy efficiency, moisture, embodied carbon and occupant wellbeing as separate issues, it would recognise the way each interacts with the others. This would help ensure that measures introduced to improve one aspect of a building do not inadvertently compromise another, allowing the construction of more resilient, efficient and comfortable buildings.