Importance of Low-e Glass?

When considering double glazing it is important to determine the best glass type to suit your needs. One essential glass type to consider is called low-e. The ‘E’ in Low ‘E’ refers to ‘emissivity.’ Emissivity is the ability of a material to radiate energy. So when glass has low emissivity, it emits low levels of radiant thermal (heat) energy.

Low-e glass has different names within the industry, and is sometimes referred to energy efficient or comfort glass. However, the way it works is the same. Reducing the emissivity of one or more of the glass surfaces significantly improves a window’s insulating properties.

To reduce the emissivity of glass, low-e coatings have been developed to be ‘spectrally selective’ to affect some wave lengths of light and not others. The sun radiates three types of light at different wave lengths; Ultraviolet (UV) light, visible light and infrared (IR) light. The low-e coating allows visible light to pass through the glass, but reflects infrared light which damages and fades interior materials, and also reflects ultraviolet light which is heat energy. Low-e glass can reduce the amount of heat that is conducted through the glass by around 30% compared to ordinary glass. The glass also improves thermal efficiency by reducing glare and unlike tinted glass, it does not compromise the amount of visible light that comes through.

A simple explanation is that low-e glass coatings work in the same way as the silver lining in a thermos. When a hot liquid is placed in a thermos, heat from the liquid tries to escape the thermos. The silver lining reflects the heat back into the thermos keeping the liquid at a hot temperature. With a cold liquid, the silver lining repels the heat from outside. Low-e glass acts as an added insulation from the outside elements, maintaining a comfortable temperature inside for longer. As a standard, Oknalux offers one pane of energy efficient glass in our double glazed system, and two panes in our triple glazed system.