What's the principle of LOW-E glass insulation?
Bella Zhang www.sggglassmanufacturer.com 2016-11-19 15:24:16
Most of the double-glazing window transfer heat by the exchange of infrared radiation from one layer of glass to another. Therefore, the transmission of radiant heat can be greatly reduced by reducing the emissivity of either surface of the double glazing glass. This is the reason of LOW-E glass come from.
For two layer clear float glass without any coating, the long-wave radiation exchange between the two layers is high, about 60% of the total exchange of heat through this layer.On the glass surface is coated with Low-E coating, The long-wave radiation exchange between the glass will be greatly reduced. Thus, Low-E made of double-layer, and the insulation effect is more excellent than single-layer glass, very suitable for cold area.
Data show that two layer clear float glass, the emissivity rate is 0.84, coated with emission rate of 0.2 coating, the radiation exchange rate is reduced by 3/4, so the heat transfer coefficient also decreases. When the thickness of the glass is 4mm and the air thickness is 12mm, the heat transfer coefficient of the double glass is about 2.8W / (m2*k). If coated with LOW-E, the heat transfer coefficient is reduced to 1.8W / (m2*k ).
The advantages of Low-E are obvious. Since the coated film is very thin, it is transparent to the short-wave radiation, making the ultraviolet and visible light pass through and opaque to the long-wave infrared radiation. In other words, in the winter to keep the indoor heat and it is difficult to emit out. In the summer will be a large number of outdoor high-temperature heat radiation reflected back, it is difficult to enter the room, so can achieve the effect of warm in winter and cool in warm. Low e glass can use as single panel(4mm-10mm low e glass), also can make in double panel, such as low e laminated glass(551 low e laminated glass), and low e insulated glass(5mm+5mm low e IGU glass,6mm+6mm low e IGU glass,8mm+8mm low e IGU glass).
Source from www.sggglassmanufacturer.com