Three is the Magic Number – Triple Glazing and the Future of Windows

Nick Shore, NSG Group

As legislative trends and market demands drive architects closer to the zero-carbon home, the pressure is on to ensure buildings are designed with energy-efficiency at their core. Every construction material is expected to demonstrate the most exceptional efficiency values possible.

Architects may particularly feel the strain when it comes to the glass that they use in windows. As they are pressured to find more and more energy efficient windows, the limits of what double-glazing can do will be reached. It’s in this context that triple-glazing has come to the fore. With three panes in each Insulating Glass Unit (IGU), triple-glazing offers unprecedented levels of thermal insulation, as well as a host of other benefits that have the potential to transform our cities’ carbon credentials.

But isn’t triple-glazing a bit overkill? A few years ago, it was viewed as the preserve of the Nordic extremes. While the benefits of converting from single- to double-glazing were clear, bulky triple-glazing units were often seen as a step too far; sacrificing too much natural light in the push for more efficient glazing.

Fortunately, this has all changed now. Advances in manufacturing techniques have made thinner, clearer panes of glass possible in recent years. With vacuum glazing products like Pilkington Spacia™ now readily available, triple-glazing units can even be created that are thinner than standard double-glazed windows – just 21mm thick. This means that modern triple-glazing can now be fitted to blend in seamlessly with almost any building façade, giving architects more freedom to specify triple-glazing without compromising on the appearance, clarity of view, or the amount of natural light entering a building.

So why is triple-glazing beginning to grow in popularity? In short; it offers unprecedented levels of thermal insulation, while preserving all of the traditional benefits of having windows. It enables stunning designs incorporating full-glass façades even in the coldest of winters.

 

Pilkington energiKare™ Triple used in a Passiv Haus renovation in London

The energy efficiency benefits of triple glazing are fairly simple – the more panes of glass, the less heat can escape. But the most effective triple-glazing units do much more. While blocking heat from escaping, they need to be effective at allowing as much solar heat gain (‘free energy’) from the sun as possible – a task made more difficult with three panes.

But it’s not just thermal insulation that makes triple-glazing such a versatile material for architects. Triple-glazing units (IGUs) contain six individual glass surfaces that can be coated with high-performance technology to enhance the window’s performance. For example, the outermost pane could be self-cleaning, while two of the inner panes are solar control and low-e coatings. The thicknesses of each pane can also be altered to improve safety, security and noise reduction performance.

So what about countries with cold winters but hot summers? From the outset it is important for architects to balance the ultra effective thermal insulation properties of triple-glazing with sufficient natural cooling systems in the buildings they design. Be it combining triple-glazing with the use of brise soleil – exterior structural shading – or simply making sure windows can be opened; the solutions are simple and the insulating benefits gained in winter will far outweigh the pause for thought when the plans are on the drawing board.

If I have one message to end on, it’s that triple-glazing isn’t scary. It has the potential to help transform our cities into the low-carbon hubs of tomorrow, and is fast becoming an essential material for the carbon-conscious architects of today. As it makes the switch from niche product to the mainstream, now is the time to understand the possibilities of triple-glazing.

Nick Shore is Sustainability Director for the NSG Group’s Building Products division. His remit is the creation and implementation of sustainability strategy to ensure it remains a core value at the heart of what the NSG Group does. The NSG Group is one of the world’s leading manufacturers of glass and glazing systems in three major business areas; Building Products, Automotive and Specialty Glass.

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