Applied directly to the glazing surface, the Low-e coating is a thin, invisible, metallic layer (several atoms thick). It is transparent to short-wave solar energy and opaque to long-wave infrared energy. Therefore, the Low-e allows most of the solar spectrum to pass through, including visible light. The coating reflects most heat energy (from room temperature objects) back to the source, keeps heat in during winter and prevents radiated heat from outside objects from entering. In comparison to conventional glazing which has high emissivity (high solar gains during the day and high radiative heat losses at night), the Low-e windows are much more efficient.
One negative aspect of the Low-e coating is that there is a slight loss of solar contribution. However, this loss is offset by its insulated value at night. Also, a decrease in UV rays means less fading of carpets, curtains etc.
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