Offline Ag-based Low-emissivity Glass Thermal Properties Of Light And Its Application

Energy saving and consumption reducing have great impact on Chinese economic developing and on our country safety.In China, energy consumption by building is about 22% of the total quantity. And energy lost by glass window and door is about 51% of that by total building. In China, the energy consumption is about 2.2 times of that in developed countries. Now the most developed technology in global energy saving glass window and door is to investigate and work out the way to control energy lost by glass in buildings, that is to use the low U glass. Now the most advanced and main energy saving methods of glass is to use Low-E IGU, which can save 40% energy than traditional glass.Up to now Low-E glass has 3 kinds, which are on-line Low-E, off-line single silver Low-E and off-line double silver Low-E. Totally, the anti energy lost performance of double silver Low-E is much better than that of off-line single silver and on-line Low-E glass. The impact on U and SC of the kinds, thickness, layer structure parameter and air in the IGU of Low-E glass is investigated. Based on the result, the mistake that the energy saving effect of double silver Low-E glass will be surely better than that of single and off-line Low-E glass now made by a lot of people will be recognized. By simulating, the energy saving effect of all kinds of glasses under different weather in different areas of China is studied, esp. that of single silver and double silver IGU is compared.The result is:1. In material kinds aspect, U value of IGU consisted of off-line silver coating is 10% to 20% better than that of IGU with SnO2. U value of the former is 1.8 W/M2K and that of the later is 2.0 W/M2K,2. In layer structure parameter, U value of IGU consisted of double silver Low-E coating is about 10% better than that of single silver coating IGU. U value of the former is 1.6 W/M2K and that of the later is 1.8 W/M2K,3. In coating thickness, the reason for the low U value of Low-E IGS is the reducing ofε. Whenεis reducing from 0.84 to 0.05, the U value is from 2.8 to 1.7W/M2K. When the silver thickness is increasing from 8.5nm to 19nm, the SC will be from 0.7 to 0.43 which will reduce the visible light transmission from 80% to 61%, 4. The air kinds of IGU have great impact on the U. When the air is changed to Argon(Ar) or Krypton(Kr), the U will be from 2.8 to 2.5 W/M2K,5. The result of the energy saving effect of all kinds of glasses under different weather in different areas of China shows that the main two parameters of IGU: U and SC have different functions in different weather areas. No matter in torrid zones or frigid zones, the U has energy saving effect. But low SC has more energy consumption in frigid zones in winter. The simulating calculation of double and single silver Low-E IGU in temperate zones(Wenzhou) and torrid zones(Guangzhou) shows that energy consumption of low U and low SC double silver IGS is less 3% and 17% than that of low U and high SC single silver Low-E glass. And in frigid zones (Haerbin) energy consumption of low U and low SC double silver IGU is more 2% than that of low U and high SC single silver Low-E glass. So in design and usage of energy saving IGU it will be necessary to consider the current weather.