In 20th century 70's intermediate stages, the people discovered the double-glazed window heat transfer the majority, is produces from glass to another glass infrared radiation exchange.Therefore, so long as reduces in the double glazing any superficial emissivity, can reduce the radiating heat greatly the transmission.This is the LOW-E glass reason.
Regarding has not plated the duplicate any coating two gonorrhea glass, the long-wave radiation exchange degree very is mutually high, approximately for always exchanges 60%. through here level quantity of heat to plate the duplicate Low-E coating in the glass surface, between two glass long-wave radiation exchanges will be large scale reduces.Thus it can be seen, Low-E makes the double-decked effect to be only then good, also the heat preservation effect is more outstanding than the single-layer glass, is suitable extremely for the winter cold north.
Some data indicated that,The white glass emissivity is 0.84, after plates has the emissivity is 0.2 coating, its radiation exchange rate reduced 3/4, therefore the heat transfer coefficient value also reduced along with it.When the glass thickness is 4mm, air thickness is 12mm, the double glazing heat transfer coefficient is approximately 2.8W/(m2*k), after if plates duplicate LOW-E, the heat transfer coefficient reduces is 1.8W/(m2*k).
The Low-E merit is very obvious, because plates the duplicate membrane to be very thin, it to the short-wavelength radiation is the base wooden transparent, causes the ultraviolet ray and the visible light passes basically, but to the long wave infrared emission is not opaque.In other words, maintains the room internal heat energy in the winter, causes it outward to send out with difficulty, but the massive heat radiations which sends out outdoor high temperature reflects in the summer in, causes it to enter with difficulty enters the inner rooms, achieves “warm in winter and cool in summer”.
Low-E divides into online and the off-line two kinds.Generally speaking the online Low-E quality quite is stable, does not look like the off-line to be such easy to oxidize expires, the life quite long mouth shortcoming lies in the heat insulation effect to be inferior the off-line is good, if wants through to add plates the multiple coat to enhance the heat insulation effect thick, then the glass color can deepen rapidly, the transmittance reduces large scale.The off-line LOow-E heat insulation effect is good, must the double-decked use, after and produces needs to process the geminate level immediately, if the craft does not arrive, plates the multiple coat easily to oxidize, creates the transparency to drop.Online and the off-line has the good and bad points respectively.
The high quality Low-E general service life may amount to above for 5 years, but with constructs several dozens years life to compare is too short.Specially off-line Low-E, easy to oxidize also fears the oxidation, no matter because is replaces the glass or replaces the instrument bezel to be able to give the building the daily use to bring the extremely big trouble.It is reported has the newest technology in US, through hits an eyelet on each glass to pour into the chemical agent, lengthens LOW-E the service life, the craft is complex, the cost is high.But no matter how, the LOW-E replacement and the maintenance were inferior obviously the membrane and spreads the medicinal preparation to come simply.