How much does the position of the glass coating surface affect the performance of insulating glass?

At present, most of the types of insulated glass used in doors and windows are double glass insulated, triple glass insulated, and double glass Low-E insulated products. With the increasing demand for energy-saving performance of doors and windows, the configuration of insulated glass for doors and windows is also developing towards double glass Low-E hollow (offline, double silver), three glass Low-E hollow, three glass double sheet Low-E or using technologies such as warm edge and inflation, and the energy-saving performance of glass will be significantly improved.

The selection of Low-E glass is increasingly valued by people, and its product series, specifications, and varieties are becoming more refined. In response to different energy-saving performance requirements, more new products have emerged.

Characteristics of Low-E Glass

Low-E glass (also known as low emissivity coated glass) is the abbreviation for Low Emission Glass, which is a film system product composed of multiple layers of metal or other compounds coated on the surface of glass. This product has a high transmittance to visible light and a high reflectivity to infrared (especially mid to far infrared), with good thermal insulation performance. It can play a role in controlling sunlight, saving energy, regulating heat, and improving the environment.

The surface emissivity e of ordinary glass is around 0.84, while the surface emissivity of online Low-E glass is generally below 0.25. This low radiation film layer with a thickness of 80nm~90nm has a high reflectivity of far-infrared thermal radiation, which can reflect more than 80% of far-infrared radiation back. Therefore, Low-E glass has a good barrier effect on the transmission of thermal radiation.

Most of the radiation from the sun can be transmitted indoors through insulating glass, bringing light and warmth to our lives. Indoor items will undergo re radiation (long waves) due to their warm temperature, and a certain amount of heat will be transferred to the outside through insulating glass. Hollow glass made of low radiation coated glass can transmit most of the visible light and solar energy from the sunlight indoors, and effectively prevent indoor re radiation (long waves) from being transmitted through the glass to the outside, thereby achieving the goal of reducing the U-value of door and window products.

In winter, the design of low radiation insulated glass in northern cities of China mainly considers shielding ultraviolet rays, high transmission of visible light (improving the utilization of natural light), high transmission of near-infrared light (obtaining solar thermal energy), and long wave (2.5 μ M~50 μ Low transmission between m (preventing indoor heat loss).

In summer, the design of low radiation insulated glass in southern cities of China mainly considers shielding ultraviolet rays, high transmission of visible light (improving the utilization of natural light), low transmission of near-infrared light (shielding solar thermal energy), and long wave (2.5 μ M~50 μ The low transmittance between m blocks the thermal radiation of outdoor objects (roads, buildings, etc.) and also prevents the loss of indoor air conditioning.

Due to the fact that Low-E glass is a film series product composed of one or several layers of silver metal thin films or other compounds coated on the glass surface, the film layer has extremely low surface emissivity, with a wavelength of 2.5 μ M~40 μ The far infrared thermal energy of m radiates back. The lower the emissivity e value of Low-E glass, the lower the U value of the glass, and the better its thermal insulation effect.

According to different processing techniques, Low-E glass can be divided into online Low-E glass and offline Low-E glass. The main difference between the two is the e-value of Low-E glass, which is generally around 0.30-0.16 for online Low-E glass; The e-value of offline single silver Low-E glass is generally around 0.15 to 0.08; The e value of double silver Low-E glass is generally around 0.05 to 0.07; The e value of three silver Low-E glass is generally around 0.02. The emissivity e of ordinary transparent glass is 0.84, which means that the wavelength can be reduced to 2.5 μ M~40 μ 16% of the far-infrared thermal energy between m is radiated back. As shown in the National Glass Database, No. 253 is an offline low radiation coated glass with a emissivity of 0.08, which means that the wavelength can be set to 2.5 μ M~40 μ 92% of the far infrared thermal energy is radiated back, making the energy-saving effect of insulating glass more significant.