The role of glass solutions
Phil Brown, European regulatory marketing manager at Pilkington UK, discusses the uplift to Part L building regulations for new and existing dwellings in England – and how it’s key that the industry has the right products available in preparation for tighter regulations.
Last June, building regulations in England were updated to implement more rigorous requirements for energy conservation.
The aim was to reduce carbon emissions in dwellings by 31% compared to the previous standard. It was an important step towards achieving the Future Homes Standard by 2025, which requires embracing carbon-saving technologies as well as improvements in building fabric standards.
A ‘fabric first’ approach prioritises a building’s materials for maximising energy efficiency. When it comes to glass and glazing, this means limiting fabric parameters for building elements such as windows or doors.
For windows in new dwellings, the current maximum U-value is 1.6 W/(m2K) but, in practice, the notional specification dwelling value of 1.2 W/(m2K) has become the ‘de facto’ standard. For replacement windows in existing dwellings, the maximum U value is now 1.4 W/(m2K).
However, the expectation is that the U-value will still have to be much lower than this to enable new dwellings to achieve the target primary energy, carbon emissions and fabric energy efficiency rates.
The role of triple glazing
Anticipated to be delivered through the next Part L, the Future Homes Standard aims to ensure new homes built from 2025 will typically produce 75-80% less carbon emissions than those constructed to the 2013 energy efficiency requirements. This target is likely to be achieved through a low carbon heating system and very high fabric standards.
The original 2019 consultation document indicated a notional dwelling window U value of 0.8 W/(m2·K), which would effectively mean mandatory triple glazed windows. Whilst we await the public consultation for Part L 2025, the glass and glazing industry is starting to make preparations for these changes by introducing more and more lower U-value windows to the market.
Glass solutions
It is not just triple glazing but a whole host of glass and glazing solutions that unlock huge potential for energy saving. Insulating glass units can be installed into many types of existing window frames and specialist coatings can modify products to make them more energy efficient.
Window Energy Ratings (WER) are often used as a means of demonstrating compliance with Part L for replacement windows in existing dwellings. They take into account the total energy performance of a window. The rating looks at heat loss, as well as the amount of the sun’s energy passing through the glazing. As an alternative to the U value compliance route, replacement windows achieving minimum WER band B can satisfy the current requirements.
Solar control glazing allows daylight to pass through a window or façade while reflecting away a large degree of the sun’s heat. For example, Pilkington Suncool is specifically designed to reduce the need for both cooling and heating systems.
Where there isn’t a need for cooling systems, incorporating a low-e glass such as a glass from the Pilkington K Glass Range or Pilkington Optitherm S1 Plus helps to prevent heat from escaping through windows, reflecting it back into the building.
Looking forward
As we look to the future, it is important for installers to be prepared for the tightening of regulations leading up to the introduction of the Future Homes Standard in 2025.
Understanding the energy performance of your chosen glass and pre-empting further tightening of the regulation will play a significant role in meeting targets in the coming years.
