By Jon Crohill, Sheerline’s technical & design office manager.

At the time of writing this article in early August, it was a toasty 34°C. A few years ago, this heat would have been unprecedented, but according to Sky News, this year there have been 34 days (including the day this was written) that have exceeded 30°C in the UK. By the time you read this, I expect this figure to have increased.

If that’s the case, we’ll have surpassed the previous record set in 1995 when there were 34 days where temperatures exceeded 30°C somewhere in the UK. The Met Office says 2025 was the warmest summer on record with a mean temperature of 16.10°C, but again, 2026 is looking likely to surpass this to become the hottest UK summer on record.

Although ‘record-breaking’ weather is quantified in different ways, whichever way you look at it – number of hot days or average temperature – our summers are getting hotter. What we’re witnessing isn’t a one-off. We’re seeing increasingly extreme weather we’re not prepared for.

Ventilation is no longer an optional nice-to-have – it is a critical necessity for a few different reasons. In part to help us cope with the extreme heat we’re facing, so there’s a comfort element, but there are also legal requirements as set out in the Building Regulations Part O (overheating) and Part F (ventilation), and it reflects the evolution of house building.

For years the ultimate goal has been thermal efficiency, which in winter means less heat escaping. We have actively been trying to make our homes more air tight to increase our efficiency and reduce our (ever increasing) energy bills – and we’ve succeeded.

But in the summer, when our homes are still air tight and built for thermal efficiency, they’re so air tight, heat can’t escape. This is where Part O and F come in. Part O looks at how overheating in residential dwellings can be mitigated.

Part F has been developed to ensure buildings have adequate ventilation. The impact of this is two-fold, it prevents overheating in summer but also reduces the likelihood of issues such as mould and condensation, which can affect air quality.

What does this mean for the fenestration industry? It’s much like the way we work with customers when they need to achieve certain U-values for a project. We need to focus on solutions for fast and effective ventilation that retain the same refined architectural aesthetic homeowners covet.
At Sheerline, we offer a couple of ventilation solutions for various applications. This includes specialist AOVs, which are ideal for apartment complexes and SheerVent, our intelligent automated roof ventilation system built for our S Series of roofing products.

For the purposes of this article, I’ll focus on SheerVent. It was developed in response to the need for a ventilation solution that could prevent excessive heat build up in roof lantern, conservatory, and lean-to style installations.

Many in the industry recognise the fact that spaces surrounded by glass have traditionally only been usable for part of the year. SheerVent – coupled with high-performance glazing that limits solar gains – has the ability to make living spaces more comfortable, for longer.

Reimagining roof vents
We have well and truly brought roof ventilation into the 21st century with SheerVent. Particularly as it’s still the only flush solution on the market. Ventilation has historically been an afterthought at best.

The result has been unsightly, ugly, chunky vents that look as though they have been stuck on top of the roof product, whether that’s a lantern, conservatory, or something else. When we set out to design SheerVent, we knew it needed to match the refined aesthetics of the S1, enabling it to seamlessly blend in.

But it’s not just the looks that it matches, it’s also fully thermally broken and uses the same high-performance glazing as the rest of the S1. Other considerations that reflect our attention to detail include the fact it’s glazed in-house under controlled conditions.

This speeds up the installation process while removing the need to seal glass units on site, eliminating weathertightness issues.

What else is great about SheerVent? It can be retrofitted, it has a large vent opening allowing for airflow, which results in fast and effective ventilation, and it can be enhanced with a discreet rain sensor that automatically closes the vent.

The topic of ventilation isn’t hypothetical or a future issue, it’s something that has to be addressed by house builders, specifiers, and developers now. In the fenestration industry, we need to supply proven solutions that balance practicality with refined aesthetics – and SheerVent delivers this.