11 min read

1. Preface

With increasingly serious energy problems, energy conservation research, especially building energy conservation, has become a topic of common concern around the world. The standards of "carbon neutrality" and "carbon energy-saving" introduced by countries all over the world have put forward higher requirements for the heat transfer coefficient of exterior windows of residential buildings, which are difficult for ordinary glass to achieve. Low-E laminated insulating composite glass combines Low-E glass, laminated glass, and insulating glass together, which not only makes up for their respective shortcomings but also effectively combines the advantages of the three. Thermal, anti-theft, and anti-condensation properties. In this article, the heat transfer coefficient, shading coefficient, and visible light transmittance of different combinations of Low-E laminated insulating glass are tested and compared, and the different characteristics of each group are obtained. Jinan LIJIANG Glass also considers factors such as energy-saving and aesthetics and pushes the best combination of Low-E laminated insulating glass products produced by Jinan LIJIANG Glass Automation Insulating Glass Equipment to readers.

2. Basic glass types and characteristics

In recent years, building materials technology in many developing countries has achieved long-term development, and more and more types of glass products have been applied to the outer guardrail structure of buildings. In the existing buildings, ordinary float glass is the most widely used. However, due to the increasingly high requirements for building energy conservation in some countries, Low-E glass, insulating glass, and interlayer will dominate the market in the future. Mainly glass.

2.1 Features of Low-E glass products

① The heat transfer coefficient K value is low, and the resistance to temperature difference is strong, which is beneficial to energy saving in winter and summer.

② The range of shading coefficients is wide, which can meet the shading needs of different regions.

③ Good comfort performance, can prevent sun exposure and balance indoor temperature.

2.2 Characteristics of insulating glass products

① Thermal insulation performance. The dry gas in the hollow layer has a very low thermal conductivity, which can effectively block the conduction of indoor and outdoor heat.

② Sound insulation performance. The hollow layer forms a good sound insulation barrier, and the sound insulation and heat insulation effect are better after filling with inert gas; the lighting is good and the weight is light. Using insulating glass as a building curtain wall, in addition to having the same heat insulation and sound insulation effects as brick walls and concrete walls, can also increase the lighting area and reduce the weight of the building structure.

③ Anti-condensation. When synthesizing the hollow, it is filled with a dry molecular sieve to ensure that the hollow layer is dry and will not condense above -40C. The dew condensation temperature on the outer surface of insulating glass is lower than that of ordinary glass.

2.3 Features of Laminated Glass Products

① Security. When subjected to an external impact, the elastic intermediate layer can absorb the impact and prevent the impact object from penetrating. Even if the glass is broken, only fine cracks like spider webs will be produced, and the fragments are firmly adhered to the middle layer, will not fall off and hurt people, and can continue to be used until replacement.

② UV protection properties. PVB film can absorb more than 99% of ultraviolet rays, thus protecting indoor furniture, plastic products, textiles, and energy saving. The architectural laminated glass made of PVB film can effectively reduce the penetration of sunlight. When sunlight directly irradiates a piece of colorless laminated glass, the interlayer film can absorb most of the heat and radiate only a small part of the heat into the room, making it difficult for indoor and outdoor heat energy to be conducted, reducing heat energy consumption, thereby maintaining indoor temperature, and also reduce air conditioning energy consumption. The same thickness of the laminated glass made of dark low transmittance PVB film has a stronger ability to block heat. In addition, the color interlayer can isolate more than 99% of ultraviolet rays, reducing the fading degree of indoor fabrics.

③ Sound insulation. Because PVB film has the function of damping sound waves, PVB laminated glass can effectively suppress the transmission of noise, especially in airports, stations, downtowns, and buildings on both sides of roads, after the installation of laminated glass, the sound insulation effect is very obvious.

④ Anti-theft. PVB laminated glass is very tough, even if the thief cracks the glass because the middle layer and the glass have firmly adhered together, it still maintains the integrity so that the thief cannot enter the room. After the laminated glass is installed, the guardrail can be omitted, which is both economical and beautiful. , but also to escape the feeling of being trapped. PVB laminated glass is widely used in European and American construction fields, and its use in China is gradually increasing. It is the preferred "green building material" for many construction projects.

The Laminated Glass Products 1

The Laminated Glass Products 1

3. The characteristics of Low-E laminated insulating glass

The Low-E laminated hollow composite product, which combines Low-E glass, laminated glass, and insulating glass, inherits the advantages of each of the three, and at the same time overcomes the shortcomings of one of the three alone. Its composition is shown in Figure 1.

Figure 1 The Low-E laminated composite product structure diagram 1

Figure 1 The Low-E laminated composite product structure diagram 1

The PVB part in the Low-E laminated hollow composite product can limit the convection of heat to the greatest extent, and the Low-E film can reflect a large amount of radiant heat back. Although this configuration has a negative impact on glass thickness and cost increase, it provides a technical guarantee for the large-scale application of laminated glass in the energy saving of outdoor curtain walls of high-rise buildings, and it is also an important factor for the energy-saving cost of large buildings. a long-term benefit.

4. The combination forms of Low-E laminated hollow composite products

In the Low-E laminated hollow composite product, the three parts of Low-E glass, laminated glass, and insulating glass are combined in different ways; the configuration of the final composite product is also different, and its energy-saving thermal insulation performance is also certain. Influence experiment In the case of ensuring that the original glass, PVB film, Low-E film layer, and intermediate spacer are all the same, according to the different configuration positions of the hollow layer, the interlayer, and the Low-E film layer, the Low-E interlayer is hollow. The composite glass can have the following 6 configuration combinations, which are numbered as sample A, sample B, sample C, sample D, sample E, and sample F, as shown in Figure 2.

Sample A: 6 mm Low-E/1.52 PVB/6 m white glass (2#)+9A+6 mm white glass

Sample A: 6 mm Low-E/1.52 PVB/6 m white glass (2#)+9A+6 mm white glass;

Sample B: 6 mm white glass/1.52 PVB/6 mm Low-E(3#)+9A+6 mm white glass;

Sample C: 6 mm white glass/1.52PVB/6 mm Low-E(4#)+9A+6 mm white glass;

Sample C: 6 mm white glass/1.52 PVB/6 mm Low-E(4#)+9A+6 mm white glass;

Sample D: 6 mm white glass (3#)

Sample D: 6 mm white glass (3#)

Sample E: 6mm white glass+9A+6 mm Low-E/1.52 PVB/6 mm white glass (4#)

Sample E: 6mm white glass+9A+6 mm Low-E/1.52 PVB/6 mm white glass (4#)

Sample F: 6 mm white glass+9A+6 mm white glass/1.52 PVB/6 mm Low-E(5#)

Sample F: 6 mm white glass+9A+6 mm white glass/1.52 PVB/6 mm Low-E(5#)

Figure 2 Structure diagram of Low-E laminated hollow composite products with different combinations

The above 6 combinations are arranged from the outside to the indoor from left to right, and the numbers: 2#, 3#, 4#, 5# indicate that the Low-E film layer is located on the glass surface represented by the number from the outdoor to the indoor. , some of the above 6 combinations are in the actual glass.

Figure 3. Line chart of light transmittance of different samples

Figure 3. Line chart of light transmittance of different samples

As can be seen from Figure 3, sample C and sample D can obtain the best transmittance

5. Optical properties analysis of samples

Transmittance and reflectance are important optical parameters for low emissivity products. The transmittance, reflectivity, and film surface color of the visible light band will directly affect the energy of sunlight entering the room, while the transmittance and reflectivity of far-infrared are important parameters reflecting the energy-saving effect of Low-E glass. Spectral curves of various combination products could see Figure 4~Figure 9.

Figure 4 Spectral curve of sample A

Figure 4 Spectral curve of sample A

Figure 5 Spectral curve of sample B

Figure 5 Spectral curve of sample B

Figure 6 Spectral curve of sample C

Figure 6 Spectral curve of sample C

Figure 7 Spectral curve of sample D

Figure 7 Spectral curve of sample D

Figure 8 Spectral curve of sample E

Figure 8 Spectral curve of sample E 

Figure 9 Spectral curve of sample F

Figure 9 Spectral curve of sample F

It can be seen from Figure 4 to Figure 9 that the transmittance of the six samples in the far-infrared range and the near-infrared range with a wavelength of 1200~2500um is 0, which means that it can block 100% of the solar radiation in this part of the region. Through the penetration, the purpose of reducing the U value of doors and windows can be achieved.

6. Comparison of thermal parameters

The thermal energy parameters of the samples are shown in Table 2.

Table 2 Sample thermal energy parameters
Serial number
glass configuration
Visible light/%


U value
Shading factor
Total solar transmittance
Relative heat gain
outdoor
indoor
transmission
reflection
winter
summer
1
Sample A
24.71
22.15
17.50
34.89
2.524
2.756
0.292
0.254
205.5
2
Sample B
14.12
25.98
19.72
39.24
2.469
2.652
0.322
0.251
202.7
3
Sample C
23.67
18.12
19.58
28.01
1.613
1.633
0.288
0.281
194.2
4
Sample D
22.6
24.81
18.12
24.73
2.51
2.75
0.528
0.181
354.1
5
Sample E
27.11
19.42
18.25
31.15
2.51
2.75
0.482
0.421
325.7
6
Sample F
21.35
23.46
31025
35.85
2.99
2.58
0.539
0.469
351.9

It can be seen from Table 2 that the U value of sample C is the smallest, and the other five samples have little change. A larger shading factor means more solar gain. On the contrary, if you choose sample F with a shading coefficient of 0.539, you can get more heat in winter, but you will pay more for air conditioning in summer. Therefore, in daily use, it is necessary to determine the corresponding configuration according to the design requirements.

7. Conclusion

Analysis of the spectral curves and thermal parameters of samples with different configurations, the best product performance is sample C, and because sample A, sample B, sample E, sample F not only have poor performance but also have the risk of film oxidation in actual production. Film adhesion problem. Therefore, in daily use, for Low-E laminated hollow composite products, the following aspects should be considered:

7.1 The change of the E value of Low-E glass affects the overall performance of the product;

7.2 When using Low-E laminated products, the relationship between the glass SC and the placement position of the Low-E surface;

7.3 When using Low-E laminated products, the relationship between the glass U value and the placement position of the Low-E surface;

7.4 Determine the Low-E laminated hollow product according to the design requirements, and the Low-E coating surface should be placed in a reasonable position.


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