RetroWAL™ Gold Series
The RetroWAL™ Gold Series uses low-e insulated glass with a low e coating on the number 3 surface and the number 5 surface and simulates the performance of triple glazing with 2 insulating air gaps. This outperforms most modern triple glazing with a center of glass U value of .18 and an R value of 5. When the Gold Series is placed behind Insulated Glass, two air gaps are created which triples the performance of the existing glazing system in the center of glass, producing a R 10 center of glass value.
The two examples above use Windows 6.3 modeling software. In each case, the RetwoWAL™ 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.