Viracon Superwindow™ Insulating Glass is an excellent choice for areas that experience unusual climatic variations. The glass features a high-performance reflective coating on the second surface and a Low-E coating on the third surface. This provides a low shading coefficient and U-value which makes our Superwindow™ more energy efficient than standard reflective insulating glass. Superwindow™ is also designed to allow the interior temperature to remain consistent, providing a more comfortable interior building environment.

Commercial Applications
This glass type incorporates two different coatings. It features a high-performance reflective coating on the number two surface and a Low-E coating on the number three surface (see Figure). By applying two coatings, Superwindow insulating glass offers low solar transmission and low radiant heat transmission.

In addition, a Superwindow insulating glass unit offers a low shading coefficient and U-value, making it more energy efficient than a standard reflective insulating glass unit.

These performance characteristics make it an excellent product choice for areas that experience unusual seasonal climatic variations.

Vision/Spandrel Match
Often a project may require spandrel glass to harmonize with the vision areas of your building. However, this is sometimes difficult to achieve when high-light transmitting or low-reflective glass types are used. Instead, the use of low-light transmitting and high-reflective glass types provide the least contrast between vision and spandrel areas under a variety of lighting conditions.

In addition, variable sky conditions can also influence our perception of glass color and general appearance. On a bright, sunny day, the exterior light intensity is approximately 50 to 100 times greater than the interior lighting level. When viewing the glass from the outside, the dominant visual characteristic is the exterior reflection.

On gray, overcast days, a greater visual disparity is created between vision and spandrel areas. This is due to the transparency of the vision glass and the perception of depth created by interior lighting. The non-vision areas tend to look flat and two-dimensional by contrast.

Because spandrel glass is virtually opaque, it can only be viewed in reflection. On the other hand, vision glass possesses a degree of transmission. As the transmission of the vision glass increases during overcast conditions, interior lighting becomes more prevalent.

Viracon recommends viewing glass samples or full-size mockups to match vision and spandrel glass areas when the vision glass light transmission exceeds 14 percent.
Greater contrast between vision and spandrel areas occurs when using uncoated, tinted glass (green, bronze, blue, etc.) or high transmission, Low-E coatings. Under these conditions, insulating spandrel units can create the illusion of depth and approximate the vision glass more closely.

By keeping the vision and spandrel glass construction similar (the same exterior glass color, coating, etc.), the contrast can be minimized under various lighting conditions. Viracon recommends a neutral colored ceramic frit on the number four surface.