RetroWAL™ Silver Series
The RetroWAL™ Silver Series is the world’s first Do It Yourself (DIY) commercial curtain wall retrofit system. It uses a monolithic or laminated piece of glass with a low-e hardcoat on the number 3 surface of the window system when placed behind the prime window. This simulates the performance of a modern insulated glass unit by creating an airgap in the existing frame and reflecting unwanted heat out of the building. The center of glass U value is reduced to .36 and the frame U value is reduced producing approximately 3 times the resistance to heat loss in the center of glass.
When the Silver Series is placed behind Insulated Glass, one air gap is created which doubles the performance of the glazing system in the center of glass.
The two examples above use Windows 6.3 modeling software. In each case, the RetroWAL™ system utilizes a 2” airspace from the existing window. The IGU is uncoated and has a ½ airspace. These values are for COG or Center of Glass.
One other factor not taken into consideration in this table is the reduction in air leakage around the gaskets of the glass. RetroWAL™ has been tested to dramatically reduce air leakage.
R Value: This is the measure of thermal resistance and is in the English units BTU/(h °F ft2).
U Value: This is the reciprocal of R value and is used in the fenestration and window industry.
SHGC: This is the Solar Heat Gain Coefficient and is the energy transmittance of the glass window due to solar radiation. It ranges from 0 or totally blocked to 1 or direct sunlight.
VL: Is the Visible Light transmitted through the glass. The idea is to maximize the amount of natural light but to minimize the solar heat of infrared radiation. The values range from 0 to 1.
Weight: This is the additional weight per square foot the RetroWAL™ system adds to the window opening. In large curtain wall buildings it is important to maintain the structural integrity of the window and add as little weight as possible.