Commonly referred to as Low-E glass, this kind of glass has a coating that reduces the ultraviolet and infrared light that passes through a window. It helps regulate temperature (and energy consumption) within a building by redirecting heat back in the direction from which it is coming. Low-E coatings are made of microscopically thin coatings of materials that reflect heat much better than it absorbs or emits it (e.g. silver and/or a metal oxide). These coatings are applied to glass either during the manufacturing process (a pyrolytic application) while the glass is still hot and forms what is called a “hard coat” as the glass cools, or after the glass has been cooled and cut, via a vacuum process called sputtering, which results in a “soft coat.”

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