The hottest glass curtain wall sunshade design adv

2022-08-08
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Sunshade design of glass curtain wall advocates the intelligentization of building sunshade system. In the 20th century, the world's building science and technology have advanced by leaps and bounds, housing construction has developed rapidly, the thermal insulation and air tightness of building envelope in developed countries have been greatly improved, heating, air conditioning and lighting equipment and technology have been improved day by day, and people are more and more able to live and work in a more abundant and comfortable indoor environment, Human architectural civilization has made unprecedented achievements. At the same time, people have to face a series of serious problems, such as resource depletion, environmental degradation, ecological damage, climate warming and so on. According to statistics, in China, a developing country, building energy consumption accounts for 27% of the total social energy consumption. With the development of economy and the improvement of people's quality of life, this proportion will continue to grow. Green buildings that emphasize energy conservation, low pollution and low energy consumption are born in compliance with the requirements of the times. China has also promulgated a series of laws and policies to make clear provisions on building energy conservation and rational use of resources

with the development of glass curtain wall in China, the total area of glass curtain wall exceeded 3million square meters last year. Metal glass curtain wall has the advantages of light weight, non combustibility, shock resistance and rapid construction. Under the premise of the requirements of high-rise buildings in modern cities, fire prevention, shock resistance and construction safety, it has become an irresistible trend and will become the mainstream of high-rise building design in the future. The metal glass curtain wall can reduce the use of a large number of steel bars and concrete in the traditional concrete exterior wall, which is of great help to reduce the use of high energy consuming building materials to save energy and resources. Moreover, the metal glass curtain wall is easy to recycle and achieve the purpose of environmental protection

glass curtain wall is the most active and sensitive part of heat exchange and heat conduction in modern high-end buildings. It is 5 ~ 6 times the loss of heat loss of traditional walls. The energy consumption of curtain wall accounts for about 40% of the energy consumption of the whole building. Therefore, the energy conservation of curtain wall plays an extremely important role

I. necessity of shading of glass curtain wall:

the energy-saving design of the outer envelope of the building is linked by factors such as window opening, orientation, shading and thermal insulation materials, which affect the energy consumption of the building. Seraya Research Office in Taiwan has studied the peripheral protective structure of office buildings in Taiwan, and analyzed the energy consumption of various elements of the building's external protective structure. The results are as follows:

location window opening rate, building orientation, external shading and glass shading factors, glass UI value, external wall insulation factor

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it can be concluded from the above:

1) the window opening rate of the external wall is the most important factor for energy saving of the external wall, and reducing the window opening area rate is the most important means for energy saving, but reducing the window opening rate must also take into account to ensure proper natural lighting and avoid the psychological sense of closure. However, for the glass curtain wall that pursues the transparent effect, the energy-saving requirements can only be achieved by reducing the open window area and strengthening the heat insulation design in the opaque area

2) external shading and glass shading are the second important factor for external wall energy saving. Both glass material and external shading affect the shading rate. However, the installation of sun visors, sun visors and other external shading is far more effective than changing the glass material. Reflective glass and heat absorbing glass with high reflectivity can be selected as the glass material (only reflective glass with too much reflectivity will cause glare pollution)

3) the building orientation factor is the third element of the energy-saving design of exterior walls (accounting for 12%). Large area glass curtain wall shall be protected from exposure to sunlight from the east to the West. The long direction of the building shall face the north-south direction

in China, with the development of market economy, building energy conservation is an urgent need for China's sustainable economic and social development. The awareness of energy conservation and environmental protection of construction units and design units has also been continuously improved, and the requirements for energy conservation of glass curtain walls have also been continuously improved. At this stage, the main measures to improve the thermal insulation performance of glass curtain walls are:

1) the use of coated glass, Low-E glass, heat reflective glass Insulating glass and other glass processing technologies to reduce the direct radiation of the sun through the glass

2) the application technology of high thermal resistance materials such as aluminum-plastic composites and heat break bridge profiles is adopted

the principle of the above thermal insulation measures is relatively simple, which greatly reduces the heat transfer coefficient of the glass curtain wall structure. These energy-saving measures have been widely used in buildings at this stage. Although the glass curtain wall building can achieve better heat insulation and energy saving effect by adopting shading measures, at this stage in China, all parties do not pay enough attention to it. The annual air conditioning power consumption of a poorly designed all glass curtain wall building may be four times that of an ordinary concrete exterior wall building. The service life of glass curtain wall is as long as 50 years, and its energy-saving effect is certainly far better than that of short-lived air conditioners, refrigerators, boilers, etc. Therefore, the energy conservation of glass curtain wall buildings is more important than that of other building products. Therefore, the development of glass curtain wall shading technology is also the most potential tool for building energy conservation

in addition, it is required in the architectural design that shading measures should be taken when the building meets the following conditions (only 1-2 rooms with high building standards):

1) the indoor temperature is greater than 29 ℃

2) when the solar radiation intensity is greater than 240 kcal/M

3) the indoor depth of sunlight is greater than 0. 5m

4) sunlight exposure indoors for more than one hour

adopting shading measures is not only a necessary means for energy-saving design of glass curtain wall buildings, but also a necessary means for architectural design of glass curtain wall buildings with high standards

II. Role and effect of sun shading

as the glass curtain wall is composed of glass and metal structure, the glass surface has strong heat exchange and high thermal transmittance, so it has a great impact on the indoor thermal conditions. In summer, the sunlight enters the room through the glass, which is the main cause of overheating in the fixed room pin. Especially in the hot areas in the south, if the human body is directly exposed to the sun again, it will feel hot and uncomfortable

setting a sunshade system on the glass curtain wall can minimize the direct sunlight exposure, thus avoiding indoor overheating. It is one of the main measures for building heat protection in hot areas. After setting the sunshade, it will have the following functions and effects:

1) the effect of sunshade on solar radiation. The thermal insulation performance of the peripheral protective structure is affected by many factors, among which the most influential index is the shading coefficient. Generally speaking, the shading coefficient is controlled by the characteristics of the material itself and the environment. Sunshade coefficient is the ratio of solar radiation through the enclosure with sunshade measures and the enclosure without sunshade measures. The smaller the shading coefficient, the smaller the solar radiation heat through the outer enclosure structure, and the better the heat protection effect. The measured shading coefficients of the main windows in Guangzhou are 17% in the west, 45% in the South and 60% in the north. It can be seen that the effect of shading on shielding solar radiant heat is that the power battery supply of 328000 kwh in the xiangningde period (catl) accounted for 25.8% of the market share, and the shading measures for glass curtain wall buildings are more effective. Graphene material was officially separated by researchers from Manchester University in northern England in 2004

2) the effect of shading on indoor temperature. Shading has an obvious effect on preventing indoor temperature rise. The experimental observation in a west facing room in Guangzhou shows that the maximum difference between room temperature with and without shading is 2 ℃ with an average difference of 1. 4℃。 Moreover, when there is shading, the room temperature amplitude is small, the time delay of the maximum value at room temperature occurs, and the indoor temperature field is uniform. Therefore, shading can reduce the cooling load of air-conditioned rooms, so shading is one of the main measures to save electric energy for air-conditioned buildings

3) the effect of shading on daylighting. From the point of view of natural lighting, shading measures will block direct sunlight, prevent glare, make indoor illumination distribution more uniform, and contribute to the normal work of vision. For the surrounding environment, shading can disperse the reflected light of the glass (especially the coated glass) of the glass curtain wall, and avoid light pollution caused by large-area glass reflection. However, as the sun shading measures can block the light, the indoor illumination will be reduced, which is more unfavorable in rainy days. Therefore, full consideration should be given to the design of shading system to meet the requirements of indoor natural lighting as far as possible

4) the effect of shading on building appearance. Most people think that COMAC has been working closely with its partner, the Russian United aviation manufacturing group, that the glass curtain wall design can only be flat, and cannot design external shading and other shading facilities. However, from many foreign cases, we can find that the metal glass curtain wall can be designed into a beautiful shading form with light metal plates and become an interesting part of the architectural modeling

the sun shading system forms a light and shadow effect on the glass wall with the appearance of the glass curtain wall, reflecting the aesthetic effect of modern architectural art. Therefore, in the European architecture industry, the external shading system has been used as an active facade element, even called the double-layer facade form. One floor is the facade of the building itself, and the other floor is the facade form of dynamic shading state. This "dynamic" building image is not because of the fashion needs of the building facade, but a new modern building form that modern technology solves the human needs for building energy conservation and enjoying nature

5) influence of shading on room ventilation. Shading facilities have a certain blocking effect on room ventilation. When the window is opened for ventilation, the indoor wind speed will be reduced by%, depending on the structure of shading facilities. It can block the rising hot air on the glass surface, which is unfavorable for heat dissipation. Therefore, attention should be paid to the structural design of sunshade

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