Phil Brown, European regulatory marketing manager at Pilkington UK, explores how the latest updates to the UK’s building regulations are reshaping glazing specification, and why getting the balance right between solar control and thermal performance has never been more important.

For much of the last century, glazing was seen as a balancing act: having a generous amount of glass in the building envelope meant more daylight and visual appeal, but it often came at the cost of winter heat loss or summer overheating. Advances in glass coatings, frame design and spacer technology have gone a long way to removing that trade-off.

Now, however, the challenge has shifted. With climate change driving hotter summers and net zero targets reshaping building standards, glazing isn’t just about comfort and efficiency – it’s about compliance.

Part O, introduced in 2022, requires new homes to be designed to prevent overheating, limiting unwanted solar gain and encouraging passive cooling. Alongside it, Part L has been progressively tightened, with further steps leading to the Future Homes Standard anticipated in 2026, which will demand a 75–80% cut in carbon emissions from new builds compared to 2013.

So, what does this mean in practice?

Compliance as a driver for design

Regulatory compliance has become increasingly important, not just for meeting performance metrics, but for delivering buildings that are comfortable, economical to run, and resilient through seasonal extremes. Orientation, glazed area, choice of glass, and shading strategies are no longer design preferences but foundational decisions.

For example, Pilkington Suncool 70/35 provides excellent solar control while maintaining a high level of light transmission, helping to keep internal spaces cooler in summer without sacrificing brightness. Furthermore, its ultra-low emissivity coating offers a very low U-value for improved thermal insulation, specifiers can create glazing combinations that help meet the targets of Part L and Part O simultaneously.

Importantly, these aren’t just theoretical gains. By selecting glass with the right solar factor – commonly referred to as G value – and U-value for the orientation and size of openings, designers can reduce reliance on artificial cooling, minimise winter heat loss and create homes that stay comfortable with lower energy demand.

This is particularly relevant for highly-glazing applications, from bi-folds and conservatories to modern apartment blocks, where high performance glass can deliver all-year round comfort and avoid costly redesigns.

Beyond regulation – design for everyday living

Glazing may not be the element homeowners think about most – although they should do – but it is one of the most influential in shaping how a home feels and functions, from the quality of natural light, to providing a view that brings the outside in, and providing comfort in different seasons.

When it is specified well, it underpins energy efficiency, carbon reductions, health, wellbeing and productivity. As regulation continues to evolve, taking a proactive approach to glazing design will be one of the most effective ways to deliver buildings that not only meet standards but enhance everyday living.

By working closely with manufacturers early in the design process, architects and developers can ensure they are choosing glass that balances appearance, performance and compliance. In doing so, they can create spaces that meet the letter of Part L and Part O – and the spirit of a net-zero built environment.