If you've been looking at replacement windows to any extent, you no doubt have heard about Low E (emissivity) glass. But what is Low E glass?
There are two types of Low-E glass: hard coat and soft coat. As you might imagine, they have different properties. In fact, they actually look different.
Hard coat Low-E glass is manufactured by pouring a thin layer of molten tin onto a sheet of glass while the glass is still slightly molten. The tin actually becomes "welded" to the glass. This process makes it difficult or "hard" to scratch or remove the tin. Often this glass has a blueish tint to it.
Soft coat Low-E glass, on the other hand, involves the application of silver, zinc or tin to glass in a vacuum. The glass enters a vacuum chamber filled with an inert gas which is electrically charged. The electricity combined with the vacuum allows molecules of metal to sputter onto the glass. The coating is fairly delicate or "soft."
Furthermore, if silver is used (and it often is) this coating can oxidize if exposed to normal air. For this reason, soft coat Low-E glass must be used in an insulated glass assembly. Sealing the soft coating in between two pieces of glass protects the soft coating from outside air and sources of abrasion. Also, the space between the two pieces of glass is often filled with argon gas. The argon gas inhibits oxidation of the metallic coating. It also acts as an additional insulator.
The two types of Low-E glass have different performance characteristics. The soft coat process has the ability to reflect more heat back to the source, meaning back outside in the summer, and back inside in the winter. It typically has a higher R value. R values are a measure of resistance to heat loss. The higher the R value of a material, the better its insulating qualities. Most studies show that windows with Low E glass are at least 3 times more energy efficient than windows with no Low E at all. When you consider the price difference, it only make sense to get Low E with your new windows.
Shelby Vinyl Products offers a full line of vinyl replacement windows on a good, better, best basis. Located in North Central Ohio, We are a statewide contractor. Contact us for a free estimate at shelbyvinylproducts@yahoo.com
