Shining a light on high-value glass
Cornwall Manufacturing’s commercial and technical director, Angus Herdman, believes that the solar performance of glass has never been more important.
Angus Herdman has spent quarter of a century with Cornwall Glass Manufacturing, establishing himself in later years as the regional IGU manufacturer’s commercial and technical director.
In that time, Angus has seen trends develop for larger panes of glass, while Building Regulations have tightened, demanding greater thermal performance, better acoustic abilities, stronger security credentials, and improved solar control.
Such is the pressure on the glass to meet these demands, that some building designers are starting to reduce the size of their windows, which is unnecessary, Angus says.
“In the 25 years I’ve been with Cornwall Glass, I’ve seen the technical performance of glass develop significantly, to the point where we can make windows that can not only keep a building’s occupants warm in the winter and cool in the summer, but – thanks to laminate interlayers – safe from intruders, and unaffected by outside noise.”
Aware that for many specifiers the performance of glass often remains a mystery, Angus has developed a training programme, which he is currently sharing with customers.
“For me, solar control is the most important part of the building,” he says. “It costs you four times more to cool your building than it does to heat it. And with the introduction of Document O, some building designers are talking about reducing the size of the windows because the buildings are starting to overheat.”
Cornwall Glass Manufacturing, part of the Cornwall Group, operates from sites in St Austell, Highbridge and Plymouth. The latter provides the foundation for the manufacture of super-sized units in a wide range of solar control, acoustic and low-e monolithic and laminated glass options. The company also has heat soaking and jumbo cutting facilities, and has invested in enhanced CNC and waterjet capabilities.
Cornwall Glass Manufacturing’s own solar control journey started 20 years ago, when Angus realised that the G-value figures for glass that he was buying in would control the amount of heat entering a building if it was used correctly in a double-glazed unit.
“We work very closely with our partner Saint Gobain, but can offer a vast array of options from many recognised manufacturers,” Angus says. “Our expertise is often called upon to engineer solutions where overheating is a problem.
“For example, we were recently involved on a project in Penzance, Cornwall, where a school was too hot for the pupils to work in effectively. We devised a solution using solar control glass, which reduced the requirement for extra ventilation, and which resulted in better security because windows weren’t left open.
“It also gave the project’s designers more freedom to specify larger areas of glass, where they were considering reducing the overall size of windows. Of course, more natural light entering schools is seen as beneficial, and has been shown to improve performance among students.”
Saint Gobain’s SKN 176 and 183 were first developed for commercial applications to provide cooler conditions for office workers. They can produce a G-value of 0.37 and a U-value of 1.0W/m2K on a 16mm cavity, while achieving a light transmittance of 70%.
Available in a 4mm outer leaf, SKN176 can also be used to manufacture a very lightweight unit and can be combined with Saint Gobain’s SGG Stadip product range for improved solar or acoustic control.
“Thanks to its versatility, glass has become a victim of its own success,” Angus says. “You can use a pane of glass to fit into a cowshed window or a greenhouse, and then you can have a pane of glass that you can walk on, that will keep heat in, will keep heat out, will stop UV, and will stop the spread of fire for up to two hours.
“We really need to change people’s perception that such a high value product is ‘just a pane of glass’, especially since we are manufacturing products that create design freedoms while complying with the Building Regulations.”