Skylights break new heights

With an increased preoccupation with creating more energy-efficient buildings, skylight manufacturers have seen a heightened demand for intelligent glazing solutions. But how do the flat roof skylights fair in comparison to their window counterparts? Justin Seldis, managing director of skylight manufacturer, Sunsquare, gives his view.

It’s been a year of unprecedented growth for the glass industry with Palmer Market Research reporting that the domestic glazing market is entering into its largest period of growth since the 1990s. The same is true for the skylight industry. Some manufacturers have seen over a 25 per cent rise in the number of orders during the last 12 months. In part, the ability of the glass itself used within rooflights has afforded a much greater degree of flexibility for building projects.

2014 was somewhat of a landmark year for the skylight industry. After all, it saw the first skylight products verified by the BSI to meet the same air permeability, weathertightness and wind resistance that windows and doors do under BS 6375-1:2009.

The skylight industry has, up until recently, been very much one step behind traditional fenestration but the momentum for specifying intelligent glazing solutions is gathering pace.

From an industry wide perspective, the most impactful development in the last couple of years has been the wider adoption of neutral solar control glass. Traditionally and more so in south facing properties, the two hour period of the day where the sun is at its most intense, was ‘controlled’ by the use of tinted glass. The rest of the glazing community was embracing solar control glass, yet the skylight industry was quite literally being ‘left in the dark’.

Thankfully, the rooflight industry has moved on considerably and in the last couple of years has embraced neutral solar control glass, developing products that are incredibly effective at manipulating their surrounding environment.

With a completely neutral appearance, neutral solar control specifications allow designers to maximise the amount of natural daylight into a room while controlling the sun’s heat. Increasingly, those specifying glass within rooflights are opting for ‘super’ neutral solar control glass; a range of highly selective coated glass that combines solar control with a high light transmission and Low E performance. Not only is there an exceptionally high light transmittance to the latest solar control glass products, typically 70 per cent, but the specification affords exceptional thermal insulation too.

With the development of glazing solutions that offer remarkable thermal performance, condensation has provided the skylight industry with a challenge.

Typically, most skylights are modern Insulating Glass Units (IGUs) designed to save energy and reduce household running costs. However, IGUs have low heat transfer coefficiency which keeps the internal glass pane warm, while the external glass cools. This makes the units vulnerable to external condensation, which ironically shows how efficient IGUs are at retaining heat.

Not surprisingly, condensation issues have been more of a concern for manufacturers of flat roof skylights than window manufacturers since the dew has nowhere to run.

What the industry is now witnessing is the growing popularity of anti-condensation glass, which delays the onset of condensation by keeping the temperature of the external glass surface warmer. The skylight industry has embraced the on-line, low-e coated products that are applied to the external face of the skylight glass, which made their way into the market at the beginning of 2014. The results have been remarkable.

Of course, as much as the latest skylight glazing specifications are about climatic control, maintenance of the glass is equally as important. However, there seems to be a lack of clarity over the performance of so-called ‘self-cleaning glass’. Now, the term ‘self-cleaning’ is arguably contentious irrespective of the glass product, but it is particularly misleading with regards to skylights.

Windows are progressively being coated with a substance that chemically bonds to the glass to even out its undulated surface, resulting in minimal cleaning. Skylights, however, do perform differently to windows with the same product application. After all, there is nowhere for the water to run on a flat-roof skylight and it will still need the occasional clean. That said, cleaning is much reduced and the benefit of applying a self-maintenance protective barrier is to make the skylight as low profile as possible, allowing the outside in. After all, that’s what skylight manufacturers continually strive for; creating an aesthetically pleasing low profile rooflight that affords the greatest amount of light.

As the glazing sector gathers pace, what is clear is that skylight manufacturing is no longer two steps behind the rest of the glazing industry. Rather, it is embracing the latest glass specifications and at the forefront of design.

2015 will undoubtedly see significant developments in product testing and quality assurance from manufacturers looking to push the boundaries of what glass as a material has to offer.