How To: How does Low E Work
Courtesy of Certincoat
Low E – How does it work?
Low E glass coatings work by reflecting or absorbing IR light (heat energy). The thickness of the Low E coating and the position in the window (#2 or #3 surface) dictate how the window will perform.
- When installed on the #3 surface of an insulated glass unit (IG), the Low E coating will reflect IR heat from inside the room to help reduce the energy loss during the cold months, thereby reducing heating costs. View flash demo
- When installed on the #2 surface of an IG unit, the Low E coating will reflect or absorb IR heat from the outside, thereby reducing solar gain and cooling costs during the warm months. View flash demo
Low E Terminnology. With Low E, solar selective Low E, hard-coat, soft-coat, sputtered, and pyrolytic terminology to deal with, you need the facts on Low E.
|CVD||CVD, or Chemical Vapor Deposition, is one of two main technologies used to manufacture Low Emissivity glass. In the CVD process, vapor directed to the hot glass surface reacts to form a ceramic coating. The resulting Low E product is often referred to as “hard coat”. Learn more about CVD…|
|Emissivity||Emissivity refers to the ability of a surface to absorb or reflect heat. An energy efficient glazing technology, Low Emissivity glass is a poor absorber of heat!|
|Hard Coat||Also known as “pyrolytic”, hard coat refers to Low E glass manufactured via the CVD process. Because the coating is covalently bonded to the glass, hard coat Low E is extremely durable.|
|MSVD||MSVD, or Magnetron Sputterering Vacuum Deposition (also known as “sputtering”), is one of two main technologies used to manufacture Low Emissivity glass. In MSVD, a metal or ceramic target bombarded with ions releases atoms to form a thin coating on a sheet of glass. The resulting Low E product is often called “soft coat” or “sputtered”.|
|Pyrolytic||See “Hard Coat” or “CVD”|
|Soft Coat||Also know as “sputtered”, soft coat refers to Low E glass manufactured via the MSVD process. Less durable than its hard coat counterpart, soft coat Low E requires special storage and handling to prevent damage to the coating.|
|Solar Heat Gain Coefficient (SHGC)||The Solar Heat Gain Coefficient (or SHGC) refers to a window’s ability to transmit solar radiation. The SHGC ranges from 0-1. A value of 0 indicates that the window functions like a wall, essentially preventing any solar energy from entering the building. A value of 1 indicates that the window functions like an opening, allowing all solar energy in. In cold climates, a high SHGC can lower heating costs by using passive solar heating. In warm climates, a low SHGC is desired to keep unwanted heat out and reduce cooling costs.|
|Solar Selective Low E||Specifically designed to enhance comfort in warm climates, solar selective Low E is a Low E glass with a low solar heat gain coefficient, like Arkema’s Sun ETM.|
|Sputtered||See “Soft Coat” or “MSVD”|
|U-Value||Also known as the K-value, the U-value is a measure of a window’s ability to transfer heat (usually given in W/m2K or Btu/hr ft2 oF). Windows with a low U-value, like Low Emissivity windows, are efficient insulators against heat loss.|