Fenestration: Vacuum Insulated Glass

The Many Benefits of the High-Performing Technology

by Rich Porayko, Fenestration Association of British Columbia

Not many people know this, but vacuum insulated glass (VIG) is not new technology.  In 1893, James Dewar invented the vacuum flask, and as early as 1913, there was a vacuum patent registered in Germany.  More recently, manufacturers such as LandGlass have developed and patented insulating glass.  “It took 100 scientists and eight years to develop,” said Art Huard, GlassCan Corporation. 

         VIG is an insulating glass unit with a 0.3 mm vacuum gap between the glass panes, which replaces the space for air or gas.  “The first thing we talk about is the proprietary edge seal with a long life cycle, which has been tested to last at least 25 years,” said Huard.  “It is a proprietary low-temperature sealing technology, which is extremely important in the vacuum insulating glass process because you are dealing with tempered glass and, if the edge seal is too hot, you can take the temper out of the glass.”

         The edge seal has a very high compression to it.  According to Huard, if you have a low compression seal between the two layers of tempered glass, you can have a transfer of energy and cause catastrophic failure of your insulated glass.  VIG has a very high-compression flexible seal that is four times higher in compression than the glass itself with no transfer of energy through the seal or catastrophic failure.

         “When 0.3 mm proprietary-shaped micro-support pillars are spaced 60 mm apart, you can see them if you look at them closely, but they basically disappear if you stand back a couple of feet,” explained Huard.  “We make sure that everybody is aware of it when we show it to them.  But, we also make sure that they realize that unless you’re looking at it, they’re not really visible.”

         The only way to make a VIG is to use fully tempered glass.  Annealed glass won’t cut it.  “We had meetings with the NRC in Ottawa, Ontario,” said Huard.  “The first question they asked us was if we were using fully tempered glass, because if it wasn’t, they weren’t interested in it.  Fully tempered glass handles wind load.  We need to have glass in contact with the pillars for this to work, so the glass has to be tempered extremely flat.  This was one of the major breakthroughs that allowed VIG to be marketable at this time.”  Not all VIGs are equal, as they can have different u-values.  A lot of performance is based on the level of vacuum that you can create and maintain.  There is a low-e coating in every VIG, which helps to improve the u-value and solar heat gain coefficient. 

         A getter is a depositor of reactive material that is placed inside of a vacuum system for the purpose of completing and maintaining the vacuum.  “When you evacuate all the air in the vacuum space, you’re going to have some stray molecules,” explained Huard.  “Picture them as tennis balls bouncing around the room, and the getter’s job is to absorb any stray molecule that lands on it.”  Hybrid insulating glass units are where the VIG unit is used as a component in a traditional insulating glass.  According to Huard, you can use any glass product on the outboard lite and a VIG on the inboard lite.

         There are many reasons to choose VIG for a project, as it maintains its strength and safety advantages against wind pressure, is lightweight, and is considerably energy efficient.  When looking at products for your next piece of construction, consider VIG.

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