China is a big energy-consuming country, of which building energy consumption accounts for more than 25%. In order to reduce energy consumption, the state has carried out three energy-saving reforms. For the first time, the building energy efficiency will be increased to 35%. The second energy saving will increase the building energy efficiency from 35% to 50%. The third time will increase the building energy efficiency from 50% to 65%. The first two times are through boilers, building maintenance. The structure and management improvement to achieve the reform goals, and the third energy conservation reform now only pays attention to the energy-saving performance of the building maintenance structure, which can account for 49% of the energy consumption of building windows and doors.

Building doors and windows are the weakest position of building insulation performance. With the continuous improvement of people's living standards, in order to create a comfortable living environment, indoor cooling or picking methods are becoming more and more common. As one of the surface maintenance of buildings, doors and windows directly affect the energy-saving performance of buildings. Improving the insulation performance of doors and windows is the main way to ensure the energy consumption of buildings. Nowadays, energy-saving doors and windows are increasingly attracting people's attention.

At the same time, with the introduction of national energy-saving regulations and building energy-saving standards, building energy-saving doors and windows have also attracted the attention of many construction businesses. In order to make real estate more competitive in the competitive environment, the theme of energy-saving doors and windows has become the focus of business media hype. However, the understanding of energy-saving doors and windows is not profound. Many advertisements for sale in real estate can be seen on the above: "The doors and windows of a certain building use the energy-saving doors and windows of a certain brand of heat-insulated bridge aluminum profiles" or "Some real estate doors and windows use a certain brand Energy-saving doors and windows of Low-E insulating glass." For energy-saving doors and windows, is it only the use of spacers and broken bridge profiles or the use of Low-E insulating glass is energy-saving doors and windows? What is the real energy-saving door and window?

The so-called real energy-saving doors and windows, not a single use of the partition bridge aluminum profiles or the use of Low-E insulating glass energy-saving materials, it is a perfect combination of a system, the comprehensive results of the performance of each link, are indispensable, to measure whether the building doors and windows are energy-saving Three main considerations are the loss of heat (exchange of heat), the convection of heat, and the conduction and radiation of heat:

1. Convection is the circulation of hot and cold air through the gap between the door and window, and the heat is exchanged by gas convection, resulting in heat loss;

2. Heat conduction is the heat transfer by the molecular motion of the material used by the door and window, and is transmitted to the other surface through one surface of the material itself, resulting in heat loss;

3. Radiation is mainly transmitted directly in the form of radiation, resulting in loss of energy consumption.

In terms of three factors, we must pay attention to the following aspects of real energy-saving doors and windows.

Firstly, the profiles of different materials are chosen to have different properties, mainly because the difference in heat transfer coefficient determines the energy consumption of doors and windows. When you choose a material, the design of the profile section is very important. In the case of aluminum alloy profiles, most of the regions now only consider the cost in terms of profile selection, and do not pay attention to performance. In terms of energy saving, ordinary aluminum alloy profiles are still used, because the thermal conductivity of aluminum alloy profiles is very large. The heat conduction is very fast, especially in the cold areas of this area, and frost, dew, ice and drowning occur in the winter. In the South, this phenomenon is only invisible to the naked eye, but it consumes a lot of energy for air conditioning.

Recently, due to a series of national policies on energy conservation and promotion, as well as continuous improvement and innovation of aluminum alloy profile technology, in order to avoid the shortcomings of aluminum alloy itself, a heat-insulated cold-bridge multi-cavity aluminum alloy profile has been developed. The way of insulating the cold bridge prevents rapid heat transfer of the aluminum alloy profile, thereby achieving energy savings. The design of the heat-insulating thermal break aluminum profile is often overlooked in the details, that is, the heat-insulating bridge aluminum profile is often neglected in detail in the design, and the heat-insulating strip on the frame and the fan material are not on the same side ( After the hardware is installed, the indoor and outdoor profiles are connected to each other through the metal hardware fittings through the heat insulation strips, so that the heat is quickly transmitted, affecting the energy-saving performance of the doors and windows, and the like.

Of course, whether the improvement of the profile can achieve energy-saving effect on the whole window, which is also related to the selection of the window type. For example, in the case of doors and windows in the form of a flat opening, the energy-saving effect of the aluminum alloy profile of the heat-insulated bridge is relatively obvious. For the sliding doors and windows, the use of insulated aluminum profiles can only be said to be difficult to get alone. Due to the structural form of the sliding doors and windows, when the doors and windows are closed, the two window fans are not in the same plane, and between the two window fans. And there is no sealing pressure around, except that the tops are overlapped by the tops, and there are gaps between the tops to form a convection phenomenon. In the Beijing area, the heat transfer coefficient and the proportion of heat consumption of the basic building components were analyzed. The content of air permeability is 23.2% of the total, and the energy consumption of air infiltration is mainly lost through the gap between doors and windows. It is conceivable that if the doors and windows in the form of push-pull are used, the energy lost by air penetration will be more serious. Sliding doors and windows, even with insulated aluminum profiles, are not energy-saving doors and windows. Due to the structure of the sliding window itself, it is meaningless to use insulated aluminum profiles.


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