Surface Designation
When describing glass products there are industry standard recommended surface designations. Each ply of glass has two surfaces. The surface facing the exterior of the building is referred to as surface #1, the back of this glass ply is surface #2. For glass units with multiple glass plies, there could be 6 or more surfaces. Shown here are a few examples:

For cooling dominated buildings, the best solar performance is achieved when the coating is applied to the #2 surface, therefore Viracon coatings are located on the #2 surface.
Viracon Product Descriptions
Viracon glass products have a primary description and a detailed description. The primary description includes an alphanumeric code for each coated glass product. The code describes the exterior glass substrate and the coating.
The first portion of the code represents the coating family. Any coating family with the letter “E” in the code is a Viracon Low-E coating and those without an “E” are Viracon Reflective Coatings. Within each family, the available coatings are identified by their nominal light transmittance. If the coating has 4 digits, the last two digits represent the SHGC.
For additional details regarding Viracon’s Product Descriptions and nomenclature, see Products.