Vacuum glazings could change the way high-performance windows are manufactured and lower their costs if Guardian Industries’ research efforts prove themselves out. Double-pane, vacuum-sealed glass units with low-E coatings could achieve R-10 or better, and perform at levels now only attained by triple-pane, low-E glazings that rely on sophisticated gas fillers for much of their performance.

"This could be a more cost-effective solution that would provide equal performance with a lower profile [thinner] glazing," says Andy Russo, market development manager at Guardian’s Science and Technology Center.

The glass panes in Guardian’s vacuum-insulated glass (VIG) are supported by permanent spacers, called pillars, that hold the panes apart after the space has been evacuated. The vacuum greatly reduces conductive and convective heat loss from the glazing unit; a low-E coating reduces radiative losses.

But creating and holding a vacuum presents manufacturing challenges that are the focus of Guardian’s R&D. "When you pull a vacuum, you have to achieve a balance in putting it all together," Russo says. "You need enough pillars to support the glass, but the more there are increases conductive heat loss. What will distinguish VIGs will be how they are cut and assembled, and how the manufacturer pulls the vacuum and bonds the edges."

Guardian has been working on its approach for a few years and may introduce its first VIGs by late 2009 or early 2010, but certainly well in advance of 2012 Department of Energy performance standards.