Understanding Low E Glass Windows

Low E glass is used for the low emissivity of heat from inside your home. By using an ultra thin metallic layer within or upon the surface of the glass, you can effectively reflect heat back to its source. Read on to learn more about low-e glass windows.

Two Types of Low E Glass

The two types of low-e glass are Hard Coat and Soft Coat. With Hard Coat, tin is added to the molten glass, which makes it difficult to scrape from the surface. With Soft Coat, a thin layer of silver is added and the glass is sandwiched with another sheet of glass. Argon gas is added to this process to ensure that oxidisation does not occur.


The inside of low-e Glass is dramatically higher in temperature than other types of glazing. During cold weather, a home furnished with Hard Coat glass would typically be 23 degrees Fahrenheit warmer than a home with single glazing. Soft Coat glass would register at 36 degrees warmer than single glazing.

Some glass manufacturers now install thin transparent Low E films between glass which to double the insulating value of Soft Coat low-e glass. Most homes lose about 25 percent of their heat through windows, so the installation of low-e glass would greatly improve those losses.