Insulating glass is a kind of glass product with energy-saving and sound insulation functions, in which the aluminum frame or adhesive strip injected with desiccant is used to separate the glass between two or more pieces of glass, and the surrounding is sealed with adhesive method, so that the middle cavity can always maintain dry gas. The energy saving of insulating glass is realized by constructing the spatial structure of insulating glass. Its dry non convective air layer can reduce the heat conduction, so as to effectively reduce its heat transfer coefficient to achieve the purpose of energy saving. In the early stage of the development of insulating glass, the insulating glass made by either fusion or welding has different structural characteristics from the insulating glass made by bonding. Fusion method and welding method insulating glass is to inject dry gas into the insulating glass cavity after the surrounding of two pieces of glass are fused or welded and sealed, so as to achieve the performance of heat preservation and sound insulation. The bonding method has a unique cavity air drying system. It is with this drying system that the improvement of the structure and process of insulating glass becomes possible. In order to improve the energy-saving performance, products such as multilayer insulating glass, Low-E insulating glass and insulating glass filled with inert gas have been developed. With the application of these new technologies and materials, the U value (or K value) of heat transfer coefficient, an important performance index of insulating glass, has been continuously optimized, and the U value of heat transfer coefficient has been reduced from greater than 2.9w/m2 • K to less than 1.9w/m2 • K, or even lower, reaching 1.4w/m2 • K. 1 Introduction to the development of insulating glass industry abroad The production technology of insulating glass originated in the United States earlier, and it was first industrialized and used in developed countries in Europe in the 1960s. Because of its outstanding unique function - energy saving, it has been promoted, produced and applied in North America, European countries, Japan, South Korea and other countries. The real wide application stems from the outbreak of the previous world oil crisis in 1973. Due to the oil embargo, energy use in western developed countries is relatively scarce, and energy conservation has become a more direct and effective means to alleviate the energy crisis. Relevant developed institutions have given sufficient attention and policy support to the use and development of insulating glass, an energy-saving product. In the production technology of insulating glass, through continuous exploration and improvement, the service performance of products is increasingly improved. In all markets, the United States is a major producer and consumer of insulating glass. In the late 1980s, the annual consumption of insulating glass reached 80million m2 at a peak. Today, the application penetration rate of insulating glass in the United States has reached 83%. At present, there are 1600 insulating glass manufacturing enterprises in Europe, with an average daily output of 650000 m2, which can produce about 229 million m2 of insulating glass every year, ranking first in the production, sales and application of insulating glass in the world. 2 development status and analysis of insulating glass industry in China The production of insulating glass in China began in the 1960s, using the manual single channel sealing process. In the early 1980s, insulating glass production equipment was introduced from Austria, the United States and other countries, and the mechanical processing double sealing process was adopted. Before 1997, there were less than 100 enterprises using machinery to produce insulating glass in China. At present, there are more than 1000 enterprises using machinery to produce insulating glass in China, and the production volume also increased from 3.5 million m2 in 1997 to 23 million m2 in 2002, and reached more than 30 million m2 in 2003. From the analysis of the current market supply and demand, the insulating glass market will still show a rapid upward trend in the near future. 2.1 reasons for the rapid development of insulating glass industry It is analyzed that the rapid development of China's insulating glass industry mainly benefits from the following two aspects (1) Relevant departments have paid more and more attention to environmental protection, energy conservation, improving residents' living conditions and other issues, and accordingly formulated a number of technical regulations and standards, such as the design standard for energy efficiency of civil buildings revised in 1995, the administrative provisions on energy efficiency of civil buildings implemented on October 1, 2001, and the announcement on the release of chemical building materials technical products No. 27 of the Ministry of construction in 2001, which has improved people's awareness of energy conservation to a certain extent, It has promoted the development of China's insulating glass industry. (2) China's national economy continues to be active, growing steadily, its economic strength has been significantly enhanced, and the country's new construction area has increased significantly. In recent years, about 1.5 billion m2 of new civil buildings (including residential and public buildings) have been built in urban and rural areas throughout the country every year, of which 700million m2 of new civil buildings have been built in cities every year. Because the increase of new construction area has driven the rapid rise in the use of insulating glass products. It is predicted that in the next 10 years, the civil buildings built and put into use in cities and towns in China will be at least 800million m2 per year. In addition, there are about 37 billion m2 of existing buildings in China. The renovation of existing buildings has also expanded the demand for insulating glass to a certain extent. The development space of insulating glass industry in China is still large. 2.2 low utilization rate of insulating glass Although the production of insulating glass in China has increased rapidly, compared with the vigorous development of China's construction market, the utilization rate and popularization rate of insulating glass are still very low. The utilization rate of insulating glass in new buildings is less than 10%, and that in existing buildings is less than 1%. The energy waste caused by the non use of energy-saving products in civil buildings is still quite serious. China's building energy consumption is 1.53 times that of developed countries, and the annual consumption of commercial energy in China is 376million tons of standard coal, accounting for 27.6% of the total terminal energy consumption of the whole society. In terms of heating areas in northern China, compared with Sweden, Denmark, Finland and other countries with more advanced energy conservation work under the same climatic conditions, the annual consumption of standard coal due to high building energy consumption is 18million tons more, with a direct economic loss of 7billion RBM. At the same time, the greenhouse gas emissions such as CO2 are 52million tons more. The key to energy conservation is how to improve the national awareness of energy conservation, and how relevant departments guide and restrict by formulating corresponding technical regulations, so as to improve the utilization rate of energy-saving products such as insulating glass. 2.3 the overall level of insulating glass industry still needs to be improved From the perspective of the technological level of insulating glass, the overall level of China's insulating glass industry lags behind developed countries. There are mainly the following problems: (1) There are many enterprises, the scale of which is relatively small, and the product quality is unstable. At present, there are more than 1000 insulating glass production enterprises in China, and more than 70% of them are small-scale enterprises, which is not conducive to the unified management of the industry, and at the same time, unstable factors are added to the product quality. Due to the great differences between enterprises in process technology level, production technology level, equipment level, management level, etc., the phenomenon of good and bad intermingled product quality is more serious, and even worse, low-quality insulating glass is still flooding the market. (2) In the selection of insulating glass raw materials, enterprises unilaterally pursue the maximization of profits, resulting in the instability of the quality of raw materials. For example, sealant is one of the main raw materials of insulating glass, which directly affects the energy-saving effect and service life of insulating glass, but the sealant materials with low quality and low price are still in mass production. (3) In terms of the configuration of insulating glass, the overall configuration level is far lower than that of foreign developed countries. In the 1990s, 20% of the insulating glass in Europe used Low-E glass, of which the proportion of Low-E insulating glass in France rose to 17% in 2000, the proportion of Low-E insulating glass in Poland was 75% in 2000, and 88% of windows in North America used Low-E insulating glass by 2000. At present, the annual output of Low-E insulating glass in Europe is about 65million square meters, and it is expected that it will increase at an annual rate of 10% in the next five years. The insulating glass produced in China is mainly "float glass + spacer strip (6mm, 9mm) + float glass", and its heat transfer coefficient u value is generally more than 2.9w/m2k, while the general standard configuration in North America and Europe is "Low-E glass + spacer strip (12mm, filled with argon) + float glass", and its heat transfer coefficient u value can be reduced to less than 1.8w/m2k. Strengthen macro management and promote the healthy development of China's insulating glass industry Energy is the driving force of the world's operation, and economic growth is always accompanied by the growth of energy consumption. From the beginning of the 20th century to the end of the 20th century, the world's energy consumption increased by about 9 times. According to the prediction of all energy agencies, the world's energy demand will double in the next 25 years. At the same time, due to the exhaustibility of fossil energy such as oil and coal, its reserves will eventually fail to meet the growing needs of the world economy, and the contradiction between supply and demand will become more prominent and acute. Facing the increasingly severe contradiction between energy supply and demand and environmental challenges, western developed countries have adopted the development strategy of conservation and development. Energy conservation refers to energy conservation, and development refers to the development of energy-saving products, energy-saving technologies and the development of new energy. The concept of energy conservation has also changed from simply saving and reducing in response to the energy crisis in the early 1970s to aiming to improve efficiency, reduce pollution, improve the quality of life and improve public relations. Energy conservation and environmental protection are the guarantee of China's sustainable development strategy. Due to the continuous improvement of China's economy, energy consumption shows a rapid upward trend. According to the latest statistics this year, China has become the world's largest coal and second largest oil consumer. Large energy consumption, low energy utilization rate, intensified contradiction between energy supply and demand, and the phenomenon of switching off and limiting electricity all over the country occur from time to time, which restricts the economic development to a certain extent. In particular, China's total building energy consumption is large, the proportion is high, the energy efficiency is low, and the pollution is serious, which has become a major problem affecting China's sustainable development, and energy conservation has become a top priority. At the same time, after the approval of the Kyoto Protocol, China has great pressure on greenhouse gas emission reduction. If the emission reduction is not controlled, it will not only affect our living environment, but also be restricted by developed countries, thus affecting economic development. In general, the energy consumption per unit building area in China is equivalent to 2 ~ 3 times that of developed countries with similar climate conditions, and building energy conservation has great potential. It is suggested that relevant institutions and departments should jointly establish energy efficiency and renewable energy management institutions, establish corresponding management systems, and make overall arrangements, unified deployment, and coordinated management for energy conservation. (1) China is a vast country with great climate differences. Relevant departments should formulate corresponding building energy-saving specifications according to the climatic conditions and economic development level of each region. In the specifications, the heat transfer coefficient of the building envelope should be clear, and the catalogue of energy-saving products that should be used should be given. (2) To promote the certification of energy-saving products, we should strengthen the energy-saving certification of insulating glass products in view of the uneven quality of insulating glass in China and the serious phenomenon of shoddy glass products being replaced by good ones in the market. Implement graded management for insulating glass production enterprises. (3) Strengthen the national supervision and random inspection of insulating glass products. National and local technical quality supervision departments should pay enough attention to this product. The insulating glass industry has developed for decades in China, but the national supervision and random inspection of this product was only conducted once in 1996. Obviously, the market supervision is not enough. (4) Strengthen the quality management of insulating glass raw materials, especially insulating glass sealing materials that have a great impact on the quality of insulating glass. The market of insulating glass sealing materials in China is relatively chaotic, which is also a problem that has plagued the competent departments of the industry and insulating glass production enterprises for many years. It is suggested to implement a market access system to reject the low-quality insulating glass sealing materials. (5) Strengthen the inspection of the use of energy-saving products such as insulating glass in the construction market. (6) In areas where economic conditions permit, hollow glass products with high configuration and low heat transfer coefficient (U value) should be promoted. Through the joint efforts of relevant departments at all levels and industry preparations, we will further standardize China's insulating glass market, improve the quality of insulating glass products, popularize the use of insulating glass products in buildings, and make the healthy and orderly development of China's insulating glass industry.
Editor:Ann Lu
