Comparison of online and offline LOW-E glass performance
1. Comparison of production processes
Online LOW-E glass is made by spraying certain chemical solutions on the surface of the hot glass during the production of float glass to form a single layer of compound film with a certain low radiation function.
Offline LOW-E glass is produced on a special production line by vacuum magnetron sputtering to uniformly deposit metallic silver and other metals and metal compounds with extremely low emissivity on the glass surface. It consists of at least five layers of film depending on the function of the function used.
2, variety and appearance comparison
The online LOW-E glass has a single variety, and the film layer is colorless and transparent, and its color depends on the color of the glass.
Off-line LOW-E glass is available in a variety of colors, such as silver ash, light gray, light blue, and colorless, and can be combined with colored glass to form a variety of colors.
3. Comparison of performance parameters
Surface radiance of online LOW-E glass E≈0.20-0.28
Surface radiance of off-line LOW-E glass E≈0.05-0.15
●6mm online LOW-E glass +9A+6mm transparent glass
U winter = 2.17 w/m2 ° C
U Xia = 2.40 w/m2 ° C
Sc=0.72
●6mm offline LOW-E glass +9A+6mm transparent glass
U winter = 2.01 w/m2 ° C
U Xia = 2.21 w/m2 ° C
Sc=0.44
Note: U winter and U summer are respectively the winter and summer U values of glass, which is the conductivity of all heat except the direct radiation of the sun.
Sc is the sunshade coefficient of glass, which measures the shielding effect of glass on the direct radiant energy of the sun.
4. Comparison of energy saving
Heat transferred through the glass:
Q=U (T-T-T) +630Sc w/m2
● The above-mentioned online LOW-E (model SG500) hollow glass components, the heat transferred into the room during the summer and outside the winter are:
Q summer = 2.4 × (35-20) + 630 × 0.72 = 489.6 w / m2
Q winter = 2.17 × (-5-20) = 54.3w / m2
● The above-mentioned offline LOW-E (model SG500) hollow glass components, the heat transferred to the city and the winter outside in summer are:
Q summer = 2.21 × (35-20) + 630 × 0.44 = 310.4w / m2
Q winter = 2.01 × (-5-20) = 50.3w / m2
The calculation conditions are: outdoor 35 ° C in summer, -5 ° C in winter, and 20 ° C in indoors.
●Conclusion: Compared with the online LOW-E insulating glass, the offline LOW-E insulating glass can save 179.2 kW per thousand square meters of lighting window in summer, and the energy saving efficiency is 36% higher. In winter, the lighting window can save 4 kW per thousand square meters. The energy saving efficiency is 8% higher.
