Energy-saving integrated design with built-in louvers + insulating glass.
Abstract: Building sun shading is widely used in European and American countries. In some European countries, almost every household uses sun shading, which records the historical footprint of sun shading development. However, building sun shading in some developing countries started relatively late, and combined with national conditions, it belongs to high-rise/super. There are many high-rise buildings, and there are still very obvious differences in the building sunshade technology in European and American countries. On the other hand, the building sunshade market in some developing countries is very large. For example, the annual new buildings in China and India account for about half of the world's new buildings. This gives the building sunshade industry an opportunity for development. In practice, some developing countries are expected to catch up and keep pace with the world's advanced level, and have the opportunity to lead the world.
The building envelope structure is mainly composed of exterior walls/floors and doors/windows/curtain walls. The exterior walls/floors are opaque structures, and the thermal insulation effect is the priority. The higher the thermal insulation effect would be better than before.
Common thermal insulation technologies, such as increasing wall thickness, improving wall materials, and adding external wall insulation layers, are now widely used and mature. As a transparent structure, doors, windows/curtain walls need to have the functions of heat preservation and ventilation, and it is necessary to adjust the comfort level of the interior of the building in the dynamics of winter and summer. It is a novel and effective means of energy-saving for structural buildings.
Keywords: external enclosure; energy-saving technology; sunshade; insulating glass
With the development of urbanization, the improvement of design level, and the enhancement of the concept of energy conservation and environmental protection, it is imminent to explore a road of building energy conservation that is suitable for developing countries. Hollow glass built-in sunshade products are the crystallization of traditional sunshade products and new technologies. It has comprehensive functions of hollow glass and sunshade products, including sunshade, heat preservation, sound insulation, lighting adjustment, fire prevention, cold resistance, privacy, and space-saving, Easy to clean, etc.
Figure 1 The "zero energy consumption buildings"
For architectural glass energy saving, it can be defined as achieving better thermal comfort, lighting comfort, and visual comfort while reducing building energy consumption to a lower level under a certain period. Dynamically adjust any functional glass with various properties, whether it is ultra-clear glass or high-efficiency selective light-transmitting Low-E glass because its performance is unchangeable, it is impossible to meet the needs of the building in all seasons and 24 hours a day. The need for thermal comfort and visual comfort. The key to energy saving of architectural glass lies in the two-way dynamic adjustment and control of thermal radiation transmittance and light transmittance. Only in this way can it be possible to finally realize "zero energy consumption buildings".
1. Energy consumption analysis of residential buildings
(1) Current status of building energy consumption
According to the "Research Report on China's Building Energy Consumption" issued by the China Construction Association Energy Consumption Statistics Professional Committee in November 2018, it is pointed out that: building energy consumption accounts for 20.6% of the national energy consumption, and building carbon emissions account for 19.4% of the national energy carbon emissions. And the carbon emissions of residential buildings accounted for 41%, and there is still an increasing trend. According to statistics, electricity is still the main source of building carbon emissions, and the overall national building carbon emissions show a continuous growth trend. In 2016, it reached 1.961 billion tons, an increase of about 3 times compared with 668 million tons in 2000, and the average annual growth rate of 6.96%. For residential buildings, energy-saving retrofitting in cold-winter and hot-summer regions is the focus of building energy conservation. With the improvement of the level of urbanization, the proportion of residential buildings will further expand, and the region with cold winters and hot summers is one of the main heating characteristics in my country. Therefore, this paper takes residential buildings in regions with cold winters and hot summers as an example to analyze the energy-saving technology of the outer envelope structure.
Figure 2 The current status of building energy consumption
(2) Heating characteristics and residential building characteristics
Strictly speaking, areas with cold winters and hot summers are not traditional heating divisions due to their special geography. Moreover, according to the history of our country and other reasons, central heating for residential buildings in areas with cold winters and hot summers has not been implemented, and only the area north of the Huaihe River in the Qinling Mountains has been implemented. Central heating, so for areas without central heating, energy-saving design materials and methods are diversified, resulting in different types of enclosure structures for residential buildings in cold winter and hot summer areas, and poor thermal performance. Due to the short heating period in regions with cold winters and hot summers, it is difficult to realize central heating in the whole space. However, regions with cold winters and hot summers are widely distributed in my country. Summer is hot and rainy, winter is humid and cold, and annual precipitation is large. From the perspective of climate characteristics and historical conditions, the application of energy-saving technologies for building envelopes in this area should be strengthened to solve building energy problems. Consumption problem. Residential buildings, as the name suggests, refer to buildings used for family living. It is the main place for people to rest and do daily activities. Therefore, the thermal performance of residential buildings directly affects people's production and life.
2. Energy-saving structural design of residential building envelope
(1) Energy-saving design of exterior window structure
As we all know, doors and windows are one of the structures with the worst thermal performance among the external enclosure components of residential buildings, which reduces the thermal comfort of the building interior and increases residential energy consumption. Considering that the proportion of doors is very small, this section takes the outer window as an example. The outer window is an essential structure for ventilation and lighting in the room. The heat transfer direction is different in summer and winter. The energy saving of doors and windows mainly depends on the heat transfer coefficient, shading coefficient, and air permeability. Considering indicators such as visible light transmittance, different material parameters have different thermal performance, so the energy-saving needs of external windows can be achieved through material adjustment. The building's energy-saving design is mainly controlled by the following aspects.
Control the window-to-wall ratio. The window-to-wall ratio is mainly determined by the orientation of the building. External windows are the weak point and shortcomings of building energy conservation. Therefore, from the perspective of energy conservation, the window-to-wall ratio should be limited. The larger the window-to-wall ratio, the more energy consumption the building will have. If necessary, the window-to-wall ratio should be controlled.
Improve the airtight performance of windows. Whether the windows are sealed or not directly determines the difference in the way and speed of indoor and outdoor cold and heat exchange. The airtightness of the windows is an important aspect affecting energy consumption. The airtightness is not airtight. It only needs to meet the required standards. From the perspective of energy saving, it can be achieved by improving the contact and sealing method between the outer window and the window frame.
Improve the insulation performance of external windows. It is mainly realized through materials and structural forms. Different materials have different thermal insulation properties, so materials with better thermal insulation indicators can be selected. However, different structural forms can significantly improve the thermal insulation performance of external windows. For example, the thin-walled solid-web structure can be replaced by a hollow structure, and a multi-layer hollow structure can be used under special conditions. Of course, it is also possible to start from the aspect of an external sunshade, through the means of an internal sunshade and external sunshade or a combination, in hot weather, absorbs the incident solar heat and prevents solar radiation from directly entering the room, which is beneficial to weaken the impact on the indoor temperature. To achieve the purpose of energy saving.
(2) Energy-saving design of exterior wall structure
The exterior wall is one of the main components of a residential building, accounting for a large proportion. It is the main medium for energy exchange between the interior and exterior of the building. The energy-saving structural design of the exterior wall is not only the performance of the wall material but also the insulation layer at different positions. Common It mainly includes external wall insulation, external wall internal insulation, and sandwich insulation (as shown in Figure 1).
Figure 3 The external wall insulation
3. Performance of built-in adjustable sunshade and energy-saving glass
(1) Shading performance
The built-in adjustable sunshade hollow energy-saving glass (as shown in Figure 2), since there are different sunshade curtains built in the hollow glass, no matter what kind of sunshade it is, the sunshade coefficient of the sunshade fabric can be selected. The minimum shading coefficient of the fabric can be lower than 0.1. When the sunshade is closed and fully extended, it can usually block 60% or more of the solar radiation, and the shading coefficient can be adjusted to <0.25 to meet the building's energy-saving design requirements in summer. It can reduce the energy consumption of air conditioning and cooling by 25%. When the sunshade is opened or retracted, the maximum value of its shading coefficient can reach the shading coefficient of glass. In winter, it can also meet the building energy-saving design requirements >0.6. Usually can reduce heating energy consumption by 10%. If there are further requirements for controlling radiant heat gain, low-emissivity coated glass can also be used for insulating glass, and the emissivity of the coated surface can reach 0.08-0.15. Long wave energy is reflected in the building. Insulating glass can also use heat-absorbing glass. The absorbed solar energy can be converted into heat energy, which can be diffused by convection to reduce the energy entering the room. Insulating glass can also use heat-reflecting coated glass to reduce solar transmittance. However, the general insulating glass with sunshade has met the requirements of using.
Figure 4 The built-in adjustable sunshade insulating energy-saving glass
(2) Thermal insulation performance
The heat insulation performance of insulating glass is generally mainly affected by the air in the air layer, the thickness of the air oxygen layer, and the thermal conductivity of the gas. Now, placing a sunshade in the insulating glass will change the heat insulation performance.
Take the 5+19A+5 insulating glass with built-in louvers as an example: when the curtains are all closed, the heat transfer coefficient is generally 2.47W/㎡K. If a sunshade fabric with a lower heat transfer coefficient is used to divide the air layer into two parts, no matter whether the conduction or convection of the air layer is reduced, the heat insulation effect will be improved.
(3) Safety performance
Insulating glass is installed in aluminum alloy windows, and its safety is reflected in wind pressure resistance, air tightness, water tightness, fire resistance, and other aspects. Since insulating glass and aluminum alloy windows are sealed with silicone sealing, compared with other external sunshades, they have obvious advantages in wind pressure resistance, impact resistance, air tightness, and water tightness. Generally, external sunshades are limited to a height below 20m, and if they exceed 20m Shading design must be checked. At present, the use of adjustable sunshade hollow glass aluminum alloy windows has been safely used to more than 50m. Because the built-in sunshade curtain with built-in adjustable sunshade glass is protected by glass, it will not be affected by cigarette butts above the floor, kindling, festival fireworks, firecrackers, etc., and the fire performance is safe. From the point of view of safety performance, adjustable sunshade insulating glass is especially suitable for high-rise buildings and coastal buildings.
(4) Operation performance
The current built-in louver insulating glass still adopts the manual operation of the magnetic control handle type (as shown in Figure 3). The operator's movements must be gentle and the acceleration should not be too large, otherwise, the handle will often fall off. Operators often make mistakes. The range of manual control is restricted by the height and arm length of the human body, so the area and size of the insulating glass are restricted. Generally, the maximum width or height does not exceed 2m. The way to improve the operating performance lies in the motor drive. If the electric drive is used, the minimum radial size of the motor determines the maximum thickness of the air layer of the insulating glass. For this reason, motors suitable for 16A and 19A need to be developed, and the thickness of the air layer in the glass of mature sunshade motors will need to be thickened. to 21A, 27A, 60A. The currently developed solar sunshade motor does not need to be connected to the city grid, which opens up a wide application space. The photovoltaic panel of the solar sunshade motor is integrated with the motor. It can be charged by the sun or the mains for the first use. After charging, it can be connected to the sunshade. The working time of the battery can be 1-2 hours. Since the sunshade motor works intermittently, 1 time each time -2 minutes, the battery has a large margin and can continue to work during dark periods. Photovoltaic panels do not require strong solar radiation and can be charged and stored as long as there is light. This new energy-driven built-in adjustable sunshade energy-saving glass is more energy-saving, safer, more convenient, and easier to operate.
Figure 5 The structural design drawing of built-in shutter insulating glass
(5) Lighting performance
The sunshade in the adjustable sunshade energy-saving glass can be adjusted. It can be stretched, retracted, opened, and closed to adjust the light in a wide range. Theoretically, it can be adjusted from full light to no light. At the same time, it ensures good indoor lighting, does not generate glare, and maintains beautiful and natural communication with the outdoors, achieving visual comfort. Adjustable sun-shading energy-saving glass is better than rolling shutter windows in terms of lighting performance and is also better than using heat-absorbing glass and heat-reflecting glass. On a sunny day, the phenomenon of turning on the lights indoors is not making good use of solar energy, and it is impossible to effectively use solar energy as one of the indoor heat sources in winter in cold regions. As a coated insulating glass, there are various energy-saving methods. In any case, the energy-saving methods for controlling or reducing radiation are static and one-way. The best energy-saving effect is only for a certain period. In actual use, it is affected by the region. Affected by the seasons, there are certain limitations, but the use of built-in adjustable sunshade hollow glass becomes dynamic, two-way, and the comprehensive energy-saving effect in all seasons is better than the former. In terms of visual comfort, generally coated insulating glass is colored and solidified, while the built-in adjustable sunshade is natural and adjustable [6].
(6) Mechanical durability
Insulating glass is sealed and glued with silica gel, butyl rubber, etc., which has high requirements for the mechanical durability of the built-in sunshade. All parts should withstand the test of more than 10,000 operating cycles. The requirements for stretching and retracting are more than 30,000 times, and opening and closing are more than 60,000 times. Ropes, fabrics, and plastic parts must withstand strong sunlight radiation. Although the glass of insulating glass is often tempered, double-tempered, and semi-tempered, the possibility of damage still exists under special conditions. However, it is very important to quickly respond to after-sales service after damage. If the manufacturer comes back to measure the size and specifications and then goes back to copy it, the repair cycle will be very long. Some companies have established a traceability identification system or a chip code reading system. Once damaged, through property management, you can use the code reader to know what company, when, what style, and what size, and you can ask the supplier immediately Search inventory information, ship as soon as possible, arrange personnel to repair and provide after-sales service. Although ordinary insulating glass also has similar problems, the built-in adjustable sunshade energy-saving glass has different specifications and different styles. Although it already has considerable mechanical durability, a better after-sales service will enhance user confidence.
4. Built-in sunshade insulating glass design
(1) Built-in sunshade insulating glass
Referring to Fig. 4, this drawstring roller shutter window includes a frame body 1, a drive assembly 2, a transmission assembly 3, and a roller shutter assembly 4. The Frame body 1 includes an upper frame 11 and a side frame 12, and the transmission assembly 3 is set In the upper frame 11, the side frame 12 is connected to both sides of the upper frame 11, the driving assembly 2 includes a handle 21 and a winding rope 22, and the winding rope 22 is connected end to end and wound around the handle 21, the drive assembly 2 also includes a control mechanism 23, the two ends of the roll rope 22 are respectively wound on the handle 21 and the control mechanism 23, and the roll rope 22 can be connected between the handle 21 and the control mechanism 23. Said control mechanism 23 moves circularly, and said winding rope 22 can move forward or reverse.
The drive assembly 2 is arranged outside the side frame 12, the drive assembly 2 is not connected to the side frame 12, and the side frame 12 does not need to be provided with guide rails and grooves for guiding the handle 21. The transmission assembly 3 is arranged between the driving assembly 2 and the roller blind assembly 4 for enabling the driving assembly 2 to drive the roller blind assembly 4. Specifically, the transmission assembly 3 includes a steering mechanism 31 and a gear set 32, the steering mechanism 31 is arranged in the upper frame 11, the control mechanism 23 is connected with the steering mechanism 31, and the steering mechanism 31 The rotation direction of the winding rope 22 can be converted into the rotation direction of the roller blind assembly 4, the steering mechanism 31 is connected with the gear set 32, and the steering mechanism 31 can drive the gear set 32 to rotate, The roller shade assembly 4 includes a roller shade tube 41 and a shade body 42.
Figure 6 The built-in sunshade insulating glass design
(2) Pull cord roller blind drive
The pull cord roller shutter transmission device includes a drive assembly and a transmission assembly, the drive assembly is arranged on the outside of the insulating glass of the insulating shutter window, and the transmission assembly is arranged on the inside of the insulating glass of the insulating shutter window, so The driving assembly includes a winding rope, a first transmission mechanism, and a second transmission mechanism, the winding rope is wound on the first transmission mechanism, the second transmission mechanism is connected with the first transmission mechanism, and the second transmission mechanism is provided with The first magnetic attraction, the transmission assembly includes a steering mechanism, the steering mechanism includes a second magnetic attraction, the position of the second magnetic attraction corresponds to the position of the first magnetic attraction, and the second magnetic attraction can follow the first magnetic attraction the magnet turns. By adopting the utility model, the rolling shutter mechanism can be controlled from the outside of the insulating glass, the installation space can be saved, and the control is convenient.
The driving assembly is arranged outside the insulating glass, the transmission assembly is arranged inside the insulating glass, the transmission assembly includes a steering mechanism and a gear set, the steering mechanism is arranged in the upper frame, and the control mechanism is connected with the steering mechanism, the steering mechanism is connected with the gear set, the assembly includes a roller shade tube and a curtain body, both ends are connected with the gear set, and the side is connected with the curtain body, and the gear can drive the roller shade tube to rotate, and when the roller shade tube rotates, it can drive the curtain body to expand or retract.
From the price point of view, adjustable sunshade insulating glass can be compared with Low-E glass (as shown in Figure 5), and the use of built-in louver insulating glass is 320 yuan/㎡ higher than that of insulating Low-E glass (taking a Chinese shutter insulating glass processing factory as an example) For example, usually half of the windows need to add sunshade facilities. If half of the windows use built-in insulating glass windows, it will only increase by 110 yuan/㎡. If the cost is calculated by using 1㎡ windows in a 6㎡ building area, that is an increase of 18 yuan per square meter of building area. Compared with the energy-saving effect, this increased cost can be fully recovered in the cost using of future .
Figure 7 The Low-E Glass
Figure 8 The insulating built-in sunshade glass
5. Conclusion
In the building shading system, it is mainly divided into two types: inner shading and outer shading. External shading can more effectively block radiant heat, so it is considered to be a more effective form of shading and is widely used in European and American countries.
Compared with it, internal shading is more private, functional, and decorative, and its energy-saving properties are weakened. Traditional external sunshade products include outdoor aluminum alloy Venetian blinds, outdoor fabric curtains/canopies, outdoor aluminum alloy hard roller blinds, etc. Built-in adjustable sunshade energy-saving insulating glass, as a relatively new external sunshade product, has been carried out in project practice in other places, and its energy-saving effect and aesthetics have been generally recognized by users.
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