At the world climate conference in Copenhagen at the end of 2009, China promised to reduce carbon dioxide emissions per unit of GDP by 40% - 45% by 2020 compared with 2005, and put it into the medium and long-term planning of national economic and social development as a binding index. At present, China's building energy consumption has accounted for 40% of the total energy consumption of the whole society, and the energy consumption of doors and windows accounts for 45% - 50% of the building energy consumption. In the future, new energy-saving technologies of doors and windows will become the focus of building energy conservation.
High energy consumption of doors and windows
With the introduction of new energy-saving standards, energy-saving doors and windows in China are favored. At present, Tianjin, Anhui and other places have also issued local building energy-saving standards, actively accelerating the pace of building energy conservation.
At present, China is in the peak period of construction, with nearly 2 billion square meters of houses built every year, but more than 97% of them are high energy consuming buildings. It is estimated that by 2020, China's high energy consumption building area will reach 70 billion square meters.
At present, more than 90% of the existing buildings of more than 40 billion square meters in China belong to high energy consumption buildings. In high energy consumption buildings, the energy consumption of doors and windows accounts for nearly half. Industry insiders said that the key to building energy efficiency is the improvement of energy-saving technology for doors and windows. Therefore, new energy-saving doors and windows is the inevitable trend of market development in the future.
A large number of new energy-saving doors and windows, such as aluminum alloy doors and windows, energy-saving doors and windows, aluminum plastic doors and windows, energy-saving doors and windows, energy-saving aluminum doors and windows, energy-saving aluminum doors and windows, energy-saving doors and windows, a large number of new energy-saving products such as aluminum alloy doors and windows, energy-saving steel doors and windows, and. According to the statistics, the market share of energy-saving doors and windows has increased by less than 50%. Therefore, vigorously develop new energy-saving products of doors and windows, whether economic benefits or social benefits, are very huge.
Evolution of German energy saving standards
In order to understand the current situation of energy-saving requirements of doors and windows in China, we must first understand the development process of energy-saving doors and windows in Europe.
Germany is a typical representative of energy saving of doors and windows in Europe (see Figure 1). The change of energy saving standards of doors and windows in Germany in the figure is the future development direction of energy saving of doors and windows in China. The heat transfer coefficient of Germany was called K value before 1995 (the same as that of China now), and then changed to U value. In 1977, Germany required that the KF value of profile should not be more than 3.5 w / m2 · K, and reduced to 1.8 w / m2 · K in 1995, nearly half of that in 1995; however, the UW value of the whole window should not exceed 1.7 w / m2 · K in 2002 and 1.3 w / m2 · K in 2009. In 32 years, the heat transfer coefficient of doors and windows in Germany has decreased by 63%, that is to say, the energy consumption has been reduced by 63%. In 2010, UW in Germany will be reduced to 1.0 w / m2 · K, and will be reduced to about 0.8 w / m2 · K by 2013. The heat transfer coefficient of doors and windows is required to be close to the wall.
By 2012, except Spain UW ≤ 3.1w/m2 · K and France UW ≤ 2.6w/m2 · K, the UW of other countries is below 2.0w/m2.k, especially in northern Europe, all of them are below 1.5w/m2.k.
China is a vast country, the complexity of climate region is equivalent to that of Europe. According to the climate conditions in different regions of China, the thermal requirements of doors and windows are different, and the farther north, the lower the heat transfer coefficient. The heat transfer coefficient requirements of windows and doors in different climatic zones in China are similar to those in Europe. The energy saving requirement of Beijing is that the kW value of the whole window is less than 2.8 w / m2 · K, which is basically the same as that in Germany in 1984, while that in Northeast China is 2.2 w / m2 · K, which is similar to that in Germany in 1995. In order to achieve the goal of building energy saving of 70%, the UW value of the whole window in Beijing area needs to reach 2.0 w / m2 · K, and the northeast area needs to reach 1.5 w / m2 · K, which is not as good as the energy saving requirements of Germany.