Safety Glass Doors and Windows Future Energy Saving Targets

The window is the weakest link in the insulation, insulation, sound insulation and safety of the entire building envelope structure. There are roughly three ways of heat loss for doors and windows: 1. Door and window frame fan and glass heat conduction; 2. Air-permeable heat exchange between door and window frame fan, between fan and glass, frame and wall; 3. Thermal radiation of window glass.

According to relevant information, the energy loss through the doors and windows accounted for about 50% of the building, of which the energy loss through the glass accounted for about 75% of the doors and windows. Under certain conditions, the thermal radiation and conduction of glass are the dominant factors leading to the loss of indoor energy. Haomeijia Door Industry reveals two major trends in glass doors and windows: Energy saving and safety As the heat transfer performance of plastics is 1/125 of aluminum, the heat transfer coefficient of single glass window is 4.3-4.6%W/M2K, which is equivalent to double glass windows. The heat transfer effect shows that the role of the window frame fan material in heat transfer in the window cannot be underestimated, but the proportion of the frame fan material in the heat transfer area of ​​the entire window is small. The heat transfer coefficient of a single glass window only reaches the performance index of building energy-saving windows and doors in some areas of southern China at this stage. The 65% energy saving policy in Beijing, the 2.8W/M2K heat transfer coefficient of doors and windows, and the 4.0-2.0%W/M2K difference in different heating areas are even greater. Therefore, with the continuous development of national building energy-saving work, the use of energy-saving glass, effectively improving the thermal performance of doors and windows will become the main goal of energy saving doors and windows.

In recent years, there has been an increase in the number of glass types available for selection, which has evolved from the traditional functions of lighting, wind, rain, and enclosure to modern composite insulation, insulation, safety, noise protection, and decorative functions. The glass used for energy-saving includes heat-absorbing glass, coated glass, double-layer (or triple-layer) glass, hollow glass, and vacuum glass. Coated glass is divided into reverse radiation glass, low-emissivity film glass and multi-functional coated glass.

The person in charge of Haomeijia Door Industry Co., Ltd. stated: “Glass is a non-metal material, although its heat transfer coefficient is only 0.8-1.0W/M·K. Since the general thickness of glass is 3-8mm, its own thermal resistance is very small, and it accounts for In terms of the area of ​​about 65-75% of windows, the amount of heat transfer is still considerable.The energy saving of glass is mainly reflected in two aspects: heat preservation and heat insulation: heat preservation reduces the loss of indoor heat energy to the outdoors by reducing the heat conduction and convection characteristics of the glass. The use of insulating glass, vacuum glass, etc.; heat insulation means that by increasing the shielding properties of solar heat radiation from the glass, the conduction of outdoor heat energy into the room can be controlled. For example, heat absorption, heat reflection, low-emissivity glass, etc. are used. brief introduction:

1, double (or three) glass; 2, hollow glass is developed from two (or three) glass; 3, heat-absorbing glass; 4, heat reflective glass; 5, low-e glass and multi-functional coating Glass; Low-E glass (ILE) and Multi-Functional Coated Glass (IMF), also known as insulating glass, have the highest solar transmittance and the smallest reflection coefficient. 80% of the visible light can be absorbed into the room by the object, and long waves radiated by more than 90% of the indoor objects can be kept indoors, which greatly improves the energy utilization rate. At the same time, it can selectively transmit solar energy, transmit most of the heat radiation energy into the room, and play a role in heat preservation and energy saving in heating buildings. Compared with ILE glass, IMF glass has the same principle in heat conduction control, but it is superior in reducing heat energy. In addition, low-emissivity glass and multi-functional glass are selective for the transmission of sunlight of different spectra, and can eliminate ultraviolet rays to prevent fading of indoor furniture, pictures, artwork, etc. due to ultraviolet radiation, and also absorb some visible light, thus preventing the occurrence of visible light. The role of light.

In addition, there is a kind of coated glass that can prevent solar radiation and outdoor heat radiation in the summer, and it mainly acts as a barrier to heat radiation in the room during the winter. It also takes into account the performance of the heat-reflecting glass on the basis of the performance of the low-emissivity glass, keeping the original low. Under the premise of radiation film layer, by changing the thickness of other film layers, the transmittance of sunlight (especially near-infrared rays) should be appropriately reduced, and the reflection and absorption of sunlight (especially near-infrared rays) should be improved, with low emissivity and low shading coefficient. .

Each of the above energy-saving glasses has its own thermal advantages and also has its own shortcomings. When using, it must be based on the geography, climate characteristics, architectural orientation, level and economic consumption level of each region, and optimize selection according to local conditions. For example, the high-rise building or the building direction and location where the sunlight is relatively abundant should select the heat-absorbing glass to give full play to the heat-insulating function of the glass, and it will not cause too much influence on the indoor light. In cold and cold climate regions, low-emissivity glass should be used. With multi-functional coated glass, in order to give full play to the glass insulation function and reduce the indoor heating load; in the areas with warm winter and hot summer, anti-radiation glass should be selected to give full play to the advantages of the thermal insulation of the glass and reduce the indoor air conditioning load in summer. For example, the use of heat-absorbing glass in the building's low-level or low-radiation building orientations and locations will not only result in inefficient heat insulation, but will affect indoor lighting and increase lighting costs. Anti-radiation glass in cold and cold climates cannot be used effectively. Solar energy will also increase heating costs; in the regions with warm winter and hot summer, the selection of low-emissivity glass and multi-functional coated glass will result in an increase in indoor temperature, which will increase the cost of air conditioning.

At the same time, although the coated glass has a certain energy-saving effect, it is in the form of hollow glass. The combination of heat-absorbing glass or anti-radiation glass with low-e glass to form an insulating glass is the best match. Solar radiation is absorbed by the heat-absorbing glass and becomes thermal energy. The radiation is turned into long-wave radiation. The long-wave radiation is reflected and isolated by the low-e glass and cannot enter the room. In the hot regions of southern China, heat reflecting film is coated on the outer glass of the insulating glass, and the low-radiation film on the inner glass is coated, which can not only reflect the solar radiation heat radiated on the glass, but also has the heat transfer ability of the heat transfer glass of the insulating glass. Weakening has a very significant effect on improving indoor thermal environment and reducing air-conditioning load.

It should be stated that the above energy-saving glass is much more expensive than ordinary monolithic glass. Insulating glass increases about 40-80 yuan per square meter, vacuum glass increases about 200-400 yuan per square meter, and hollow coated glass increases about 100-300 yuan per square meter (because of the variety, performance and thickness of the film, different). However, the use of energy-saving glass energy-saving effect is very significant, higher cost performance. When choosing, full consideration should be given to the economic effects of energy conservation that are obtained through long-term use. It must not be due to price factors. There are also differences in the energy-saving effects of various structural glass. In recent years, with the strengthening of multi-storey, high-rise building development and standardized management of buildings, the safety performance of glass has begun to be highly valued by the state. In 2003, the National Development and Reform Commission, the Ministry of Construction, the General Administration of Quality Supervision, Inspection and Quarantine, and the State Administration for Industry and Commerce jointly issued the "Regulations on the Administration of Architectural Safety Glass". It is clearly stated that safety glass must be used in 11 locations where buildings require glass as a building material. Including the outer windows of the 7-storey and 7-storey buildings, the window glass or glass bottom with an area of ​​more than 1.5 square meters is less than 500mm floor-to-ceiling windows etc.

Safety glass mainly refers to tempered glass, laminated glass, and other glass products processed by tempered glass or laminated glass, such as safety insulating glass, in compliance with current national standards. Monolithic semi-tempered glass (heat-reinforced glass) and monolithic medium wire glass do not fall into the category of safety glass. The notice proposes a series of specific regulatory requirements and measures from the aspects of production, inspection, use, and architectural design, management, construction, supervision, and acceptance of safety glass. From the above discussion, it can be seen that with the increase of building energy conservation policies, the standardization of building management standards and the level of science and technology in the glass industry will increase, and energy-saving glass, safety glass, and environmental protection glass will surely shine in the future construction and become more and more important. The effect.

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