Comparison and Research on building energy conserv

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Comparison and Research on building energy conservation and door and window selection

as an important part of building enclosure, whether doors and windows can cooperate with the wall to play a good role in heat preservation and insulation and reduce the loss of indoor energy plays a vital role in building energy conservation and emission reduction. At present, there are many kinds of doors and windows, showing the trend of diversified development of aluminum, plastic, steel, wood, glass fiber reinforced plastics, aluminum plastic composite and aluminum wood composite. In order to meet the building energy-saving policy, manufacturers of various kinds of door and window materials have taken the train of energy-saving doors and windows after a little improvement. At present, there are different opinions on which kind of doors and windows should be selected as the first choice of energy-saving doors and windows in architectural design, and which kind of doors and windows can be called energy-saving doors and windows. In order to make designers, construction units and general owners have reference in the selection of doors and windows, we have made some research, comparison and improvement on the current commonly used door and window varieties for the reference of relevant units and practitioners

whether the doors and windows are energy-saving depends on two aspects, leading: what is the material of the window frame and window sash frame (hereinafter referred to as the frame), and whether it is heat insulated; Second: whether insulating glass is used in the glass; This is the most basic requirement. It is widely accepted that insulating glass should be used for energy-saving doors and windows. The remaining problem is the thermal insulation performance of the frame. Obviously, aluminum alloy, color steel and other metal materials have high heat transfer coefficient and are not insulated; Plastic and glass fiber reinforced plastic materials have low heat transfer coefficient and heat preservation and insulation, which is also common sense. Therefore, the conclusion is very clear. Doors and windows made of plastic and FRP frames and insulating glass are heat insulation and energy-saving doors and windows. Aluminum alloy frame with insulating glass is not energy-saving doors and windows

the problem is far from so simple. Although plastic doors and windows have good thermal insulation and energy-saving performance, they have the disadvantages of single color, easy fading after coloring, and rough frame. In addition, there is a lack of supervision over the rough manufacturing of workshops in recent years. There is a misunderstanding in people's consciousness that plastic windows are low-grade goods, which makes general developers unwilling to use plastic windows. The promotion of FRP doors and windows is not effective, and few people pay attention to it. Let's look at the other side of the problem. Although aluminum alloy doors and windows are not energy-saving, their appearance is quite scratchy, delicate, colorful and not easy to fade, leaving people a deep impression of aluminum alloy doors and windows, that is, high-end doors and windows, and they are deeply rooted

in view of this, the manufacturer of aluminum alloy profile has introduced the bridge breaking heat insulation aluminum alloy profile. The doors and windows made of this profile are called energy-saving doors and windows, and the relevant units have also issued a atlas to recommend it. In fact, its heat insulation efficiency is limited, and it essentially belongs to metal doors and windows. The problem is that this kind of misleading has spread rapidly under the interaction of the promotion of manufacturers, the thinking set of developers' design departments, the laxity of testing institutions and the weak supervision of competent departments. Until recently, with the promulgation of the "building energy efficiency regulations" of the State Council, the regulatory departments at all levels went deep into the scene, which exposed this problem. After testing, the thermal performance of the bridge broken thermal insulation aluminum alloy doors and windows is far from meeting the requirements. The following is a brief analysis of the structure and performance of the bridge breaking heat insulation aluminum alloy doors and windows and profiles:

this profile is composed of two aluminum alloy profiles and a group of resin heat insulation strips, which is intended to block heat conduction. Zz91 information: the quality of 3D printing materials will affect the printing effect. At present, there are two kinds of preparation processes for this type of materials: one is the extrusion synthesis of ready-made nylon heat insulation strip hobbing, and the other suitable materials: plastic plates, pipes, profiled materials. Polyurethane materials are injected into the overall profile structure groove, and the connection part of the profile is cut off after the resin is cured. We know that there are three ways of heat conduction: first, object conduction; Second, radiation; Third, convection. The bridge breaking profile only uses the low heat transfer of resin material to block or reduce the heat conduction on the object, and there is no measure to resist radiation conduction and convection conduction. The doors and windows made of this profile form a surrounding cold cavity between the closed door and window outer frame and the window sash frame. At the same time, a cold cavity is also formed in the window sash glass notch, and outdoor heat enters the room through this channel

it is not difficult to see that the profile insulation strip (diagonal part) solves less than one third of the heat conduction of the whole frame. If this kind of profile is used to make the door and window frame, coupled with 5+12+5 insulating glass, after calculation, the window frame accounts for 35% of the door and window area, and the glass accounts for 65%. The thermal performance K value of this door and window is only 3.3, equivalent to grade 8, which is not up to the lower limit of the energy-saving requirements stipulated by the local governments of Shanghai and Beijing. Obviously, the bridge broken thermal insulation aluminum alloy doors and windows have a certain thermal insulation effect, but not energy-saving doors and windows. So, is there a popular variety of doors and windows that not only has the advantages of heat preservation and energy saving of plastic doors and windows, but also has the beautiful appearance of aluminum alloy doors and windows? The answer is yes. After comparative analysis, we designed an improved aluminum-plastic composite door and window. This kind of door and window is made of colored aluminum alloy material on the outside and PVC material on the inside, so it not only has the characteristics of aluminum alloy doors and windows, but also has the good advantages of heat preservation and energy saving of plastic doors and windows. At the same time, the aluminum alloy frame is embedded in the abdominal cavity of the plastic frame, and the plastic profile is wrapped with the aluminum alloy profile after welding, which not only retains the advantage that the plastic doors and windows do not leak into the wall, but also eliminates the problem of water seepage at the corner of the aluminum alloy doors and windows that has been difficult to solve for a long time. It can be seen from Figure 2 that a large number of cold cavities exist in the broken bridge aluminum alloy doors and windows, which become warm cavities in this aluminum-plastic composite structure, so as to achieve the thermal insulation effect

the scheme is feasible, and the thermal performance needs to be demonstrated. According to the research results and data provided by cuixijun and liaojianfeng, "determination method and correlation analysis of heat transfer coefficient of energy-saving windows", the PVC part in this design scheme conforms to the characteristics of two cavity plastic window frame, and its heat transfer coefficient should be 2.1k; If the ordinary insulating glass with 5 +12+5 affects the beauty of the interior, the heat transfer coefficient of the insulating glass with this configuration is about 3.0 according to the research results and data of Lu Shuren's "principles and elements of energy saving of doors and windows"; The window frame accounts for 35% and the glass accounts for 65%. According to the simple table lookup algorithm, the heat transfer coefficient of the whole window is 2.7, which is in line with the building energy-saving goal of 50% energy saving. This proves that the design scheme is feasible. In the practical application of a project in Shanghai, the test result achieved a k value of 2.6. Of course, the universal application of this research and design and the realization of the energy-saving goal also depend on the careful design of the profile section and the control of the assembly process. In the processing process, we should attach great importance to the quality control of the welding process and the configuration of hardware accessories. We believe that by constantly summarizing experience and improving in application, this kind of heat preservation and energy-saving effect is obvious, and the appearance is very popular. Resource-saving and economical energy-saving doors and windows will certainly become an excellent variety of energy-saving doors and windows in architectural design

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