How to choose doors and windows?

Recently, many readers and fans in the system door and window group have been asking questions about Low-e glass. People are paying more and more attention to the role of good doors and windows in heat insulation, sound insulation, and radiation insulation. I have compiled the 20 most frequently asked questions in the group, hoping to be of some help to you when choosing door and window glass.

Before introducing low-e glass, everyone should follow my ideas and learn about the relevant knowledge of door and window glass step by step.

1. Why should we consider the type of glass when choosing doors and windows?

1. Many people will ask, isn’t it enough to choose profiles when choosing doors and windows? Why even consider glass? That’s because glass is responsible for lighting, heat preservation, sound insulation, safety and beauty, etc., and is an important part of doors and windows. Moreover, there are more and more types of glass now, and every family can choose different types of glass according to their own needs.

2. Secondly, there is another reason that good doors and windows are composed of profiles, glass, hardware, auxiliary materials, design and construction, etc. Glass, as the main raw material of aluminum alloy doors and windows, has excellent performance and The quality directly determines the performance of doors and windows.

▲ The Yipin Xinge system doors and windows inspected by Xiongda are of excellent quality, and are extremely cost-effective among domestic system doors and windows

2. What are the common types of door and window glass on the market?

The door and window glass we usually use in home decoration can be roughly divided into the following five types: Flat glass Glass, tempered glass, insulated glass, laminated glass and coated glass. Let me introduce them respectively.

1. Flat glass

Flat glass is also called white glass or glass. Clean sheet glass, which has the properties of light transmission, transparency, heat preservation, sound insulation, wear resistance, and climate change resistance. The main physical performance indicators of flat glass: refractive index is approx. 1.52; transmittance is more than 85% (glass with a thickness of 2 mm, except for colored and coated ones); softening temperature 650~700°C; thermal conductivity 0.81~0.93 W/(m·K); expansion coefficient 9~ 10×10-6/open; specific gravity is about 2.5; bending strength is 16~60 MPa. Flat glass depends on the production process. It can be divided into ordinary flat glass and float flat glass. Float glass is generally installed on aluminum alloy doors and windows.

The advantage of flat glass is that it has good flatness, no water ripples, and is economical. The disadvantages are also obvious: poor safety and poor sound insulation, so it is not recommended to install them on current aluminum alloy doors and windows.

Float flat glass

2. Tempered glass

Toughened glass is flat glass that has undergone a heat treatment process and has compressive stress on the surface. Glass, also known as tempered glass. The glass is reinforced by the tempering method, which has high safety (even if the tempered glass is broken, the fragments will break into small obtuse-shaped particles similar to honeycombs, which are not likely to cause serious harm to the human body), strong impact resistance and good thermal stability. , it is widely used in China. The following features:

1) Safety. When the glass is damaged by external force, the fragments will break into small obtuse-shaped particles similar to honeycombs, which are not likely to cause serious harm to the human body.

2. ) High strength. The impact strength of tempered glass of the same thickness is the highest. 3 to 5 times that of ordinary glass, and its bending strength is 3 to 5 times that of ordinary glass.

3) Thermal stability: Tempered glass has good thermal stability and can withstand the temperature difference that ordinary glass. 3 times, can withstand temperature changes of 300℃

Tempered glass

3. Insulated glass

Insulated glass is composed of two or more layers of flat glass surrounded by high strength and high air tightness. Composite adhesive is used to bond and seal two or more pieces of glass with sealing strips and glass strips. Dry gas is filled in the middle and desiccant is filled in the frame to ensure the dryness of the air between the glass pieces. Superior to ordinary double-glazed glass, so it gets It has been recognized by countries all over the world. It can be divided into ordinary insulating glass (composed of float glass, which has the three basic functions of insulating glass: sound insulation, energy saving, and anti-frost) and composite insulating glass (composed of tempered glass or laminated glass). Glass, coated glass combination In addition to the three basic functions, composite insulating glass also increases the safety and aesthetics of the glass)

1) Features: wide application range and good thermal insulation performance;

2) Common specifications: 5+9A+5, 5+12A+5, 6+12A+6, 5+20A+5 (Note: 5+12A+5 means 5mm glass + 12mm gas layer + 5mm glass)

3) Applicable places: Suitable for doors, windows, and sunrooms (note: except for sunroom roofs)

4) Inapplicable places: Living next to roads and railways and other scenes with high low-frequency noise, sunroom roofs

5+9A+5 insulating glass

4. Laminated glass

Laminated glass is also called laminated glass. It is composed of two One or more layers of organic polymer interlayer are sandwiched between one or more pieces of glass. After special high-temperature pre-pressure (or vacuuming) and high-temperature and high-pressure process, the glass and the interlayer are permanently bonded into a composite glass product. . Commonly used interlayer films for laminated glass include: PVB, SGP, EVA, PU, ​​etc. Laminated glass can be divided into flat laminated glass and curved laminated glass according to product shape. Flat laminated glass is the most commonly used in building doors and windows.

The biggest characteristics of laminated glass are three points: safety (even if the glass is broken, the fragments will not fall off for a while), sound insulation (PVB film can well control the spread of sound), anti- Ultraviolet rays (PVB film can effectively filter ultraviolet rays and protect valuable furniture)

1) Features: The sound insulation effect is better than that of insulating glass, and it is safe, but the heat insulation is worse than that of insulating glass;

2) Common specifications: 5+0.76PVB +5, 6+0.76PVB +6, 8+1.14PVB +8 (Note: 5+0.76PVB +5 means: 5mm glass + 0.76mm thick PVB film +5 mm glass)

3) Applicable places: sun roofs, indoor partitions and other safety requirements scenes; scenes with high sound insulation requirements;

4) Inapplicable places: bay windows , south-facing bedrooms and other scenes with strong thermal insulation requirements;

Laminated glass

5. Coated glass

Coated glass glass) is also called reflective glass. Coated glass is coated with one or more layers of metal, alloy or metal compound films on the surface of the glass to change the optical properties of the glass and meet certain specific requirements. Coated glass can be divided into different categories according to the different characteristics of the product. The following categories: heat reflective glass, low-emissivity glass (Low-E ), conductive film glass, etc.

The commonly used coated glass in home decoration is Low-E glass. Low-E glass has high transmittance of visible light and high reflection of infrared rays. High efficiency, so it has good thermal insulation performance and energy saving effect. It can be divided into high permeability types according to different models. Low-E glass, sunshade Low-E glass and double silver Low-E glass (double-layer coating)

1) Features: Significantly reduce the thermal conductivity of the glass, thereby improving the thermal insulation performance of the glass. .

2) Common specifications: 5Low-E+12A+5, 6Low-E+12A+6, 6Low-E+12A+5+0.76PVB+5 (Note: 5 Low-E+12A+5 means 5mm Low-E coated glass + 12 mm gas layer + 5mm glass)

3) Applicable places: Suitable for scenes with large glass use area and sufficient lighting. , such as the south bedroom, sun room, bay window sill

4) Inapplicable places: The shade, kitchen, bathroom and other places are of little use.

Low-E glass thermal insulation principle diagram

3. Regarding Low-E glass, everyone needs to know the knowledge

In fact, strictly Generally speaking, Low-E coated glass is not a classification of glass;Glass coating process. At present, it has been widely used in door and window glass for home decoration. Next, I will give a detailed introduction and answer to this kind of glass.

1. What is Low-E glass?

Low-E glass is low-emissivity glass. It is formed by coating the glass surface to reduce the emissivity E of the glass from 0.84 to below 0.15.

2. Why use Low-E glass?

1) The indoor lighting effect is good, the visible light transmittance is high, and it is transparent.

2) Allowing a large amount of solar heat radiation to enter the room in winter can increase the indoor heat energy.

3) It can reflect the far-infrared heat energy emitted by the heater, household appliances and human body in the sun room into the room, reducing the energy loss caused by heating.

4) The colors are diversified, fresh, natural and elegant, and can meet different design requirements.

5) It has good noise reduction and sound insulation performance. If the hollow layer is filled with inert gas, the performance will be better.

6) It has good energy-saving effect, which can reduce the operating energy consumption of the building and reduce the installed capacity of air conditioners, which is beneficial to environmental protection.

▲ Look at a table comparing the daily energy consumption of Low-E glass with ordinary glass and insulating glass

3. Why does Low-E film reflect heat?

Low-E film? The layer is plated with silver, and silver can reduce more than 98% of the The far-infrared heat radiation is reflected out, thus directly reflecting heat like a mirror reflecting light. The shading coefficient Sc of Low-E can be from 0.2 to 0.7, so that the direct solar radiation energy entering the room can be controlled as needed.

4. What is heat reflective glass?

Heat reflective glass is commonly known as coated glass, which is coated on the surface of the glass. , which reduces the shading coefficient Sc of the glass from 0.98 (6mm transparent glass) to 0.2~0.6.

5. What is the functional difference between Low-E glass and heat-reflective glass?

Heat-reflective glass is made by reducing the temperature of glass?The shading coefficient of the glass limits the direct solar radiation entering the room through the glass, thereby achieving the purpose of reducing air conditioning costs and saving energy. Low-E glass reduces the U-value of the glass and limits the penetration of far-infrared heat radiation through the glass, thereby reducing the amount of convective heat energy transmitted through the glass. At the same time, the shading coefficient Sc of Low-E glass has a wide adjustment range, which can effectively control the direct solar radiation entering the room.

6. What are the main mature coated glass processes?

There are two main types: online coating and vacuum magnetron sputtering coating (also called offline coating). Online coated glass is manufactured on a float glass production line. This kind of glass has a single variety, poor heat reflection performance, and low manufacturing cost. Its only advantage is that it can be hot-bent. Coated glass manufactured by vacuum magnetron sputtering process has rich varieties, excellent heat reflection performance and obvious energy-saving characteristics. The disadvantage is that it cannot be hot-bent.

7. Can Low-E glass be used as a single piece?

Low-E glass manufactured by the vacuum magnetron sputtering process cannot be used as a single piece and can only be synthesized into insulating glass or laminated glass. But its emissivity E is far lower than 0.15 and can be as low as 0.1 or less. Low-E glass manufactured by the online coating process can be used as a single piece, but its emissivity E = 0.28. Strictly speaking, it can no longer be called Low-E glass (scientifically, an object with an emissivity E £ 0.15 is called low emissivity object). Low-E glass is most effective in a similar enclosed space formed within sealed insulating glass, because this enclosed space eliminates air flow on the Low-E surface, allowing Low-E glass to function better.

8. Are the properties of Low-E glass the same?

From a technical perspective, all Low-E glasses handle spectral curves in the same way, but not all perform the same.

9. Do all Low-E glasses look the same?

It’s different! Some Low-E products appear to be highly transparent, with transmittance above 60% and light color. Some Low-E glass seems to have low transparency, with a transmittance below 55% and a relatively darker color. 10. Does Low-E glass still work at night?

Yes! Low-E glass works day and night. In winter, heat (far-infrared thermal radiation) will be reflected back into the room day and night, because the heat, whether generated by heating or converted from solar energy, exists in the form of far-infrared thermal radiation.

11. How does Low-E glass work in summer and winter?

In winter, the indoor temperature is higher than the outdoor temperature, and far-infrared heat radiation mainly comes from indoors. Low-E glass can reflect it back into the room to keep the indoor heat from leaking out. For part of the solar radiation from the outdoors, Low-E glass can still allow it to enter the room. This part of the energy is absorbed by indoor objects and then converted into far-infrared heat radiation and remains indoors.In summer, when the outdoor temperature is higher than indoors, far-infrared heat radiation mainly comes from the outdoors. Low-E glass can reflect it out and prevent heat from entering the room. For solar radiation from outside, you can choose Low-E glass with a low shading coefficient to limit its entry into the room, thereby reducing cooling costs (air conditioning costs).

12. On which surface of insulating glass is the Low-E film layer most suitable?

The insulating glass has 4 surfaces, the numbers from outdoor to indoor are 1#, 2#, 3#, and 4# surfaces respectively. In areas where heating demand exceeds cooling demand (northern region), the Low-E film layer is located on the #3 surface. On the contrary, in areas where cooling demand exceeds heating demand (southern region), the Low-E film layer should be located on the #2 surface.

13. What is the function of filling argon gas in insulating glass?

Argon is an inert gas with poorer heat transfer properties than air, so filling it into insulating glass can reduce the U-value of insulating glass and increase the thermal insulation of insulating glass. For Low-E insulating glass, argon also has the function of protecting the Low-E film layer.

14. What are the negative effects of ultraviolet rays?

Ultraviolet rays are short-wave radiation, invisible to the naked eye, and account for about 2% of the total energy of solar radiation. Ultraviolet rays can kill bacteria, but long-term exposure can burn human skin and eyes, and can also cause furniture and clothing to fade.

15. How much ultraviolet rays can Low-E glass attenuate?

Compared with ordinary single-piece transparent glass, Low-E glass can reduce ultraviolet rays by 25%. Compared with heat-reflective coated glass, Low-E glass can reduce UV rays by 14%. Low-E glass cannot completely prevent furniture from fading, but it can slow it down.

16. What impact does Low-E glass have on indoor plants?

It has no adverse effects on most common plants. For the effects on special rare plants, please consult the relevant flower experts.

17. Do shades, trees, awnings, etc. affect the performance of Low-E glass?

These objects can limit the heat and light entering the room through the glass window, which blocks part of the solar energy from transmitting, but does not affect the performance of Low-E glass.

18. Which direction is best to install Low-E glass?

In winter, no matter which direction the Low-E glass is facing, it will not affect its function, because it mainly reflects indoor heat. But the installation effect facing north is the best. After all, while Low-E glass prevents indoor heat loss, it also limits solar radiation to some extent. In summer, Low-E mainly reflects outdoor heat, so installation in any direction is suitable, but installation in the east, west, and south directions has the best effect, because it can also reduce the transmission of solar energy.

19. How long does the Low-E film last?

The duration of the coating layer is the same as the duration of the sealing of the insulating glass space layer.

20. What is the effect of combining Low-E glass with tinted glass?

There are three combination methods: coating Low-E film on tinted glass, synthesizing insulating glass with tinted glass, and synthesizing laminated glass with tinted glass. Tinted glass can further reduce the shading coefficient of combined glass products, thereby limiting the number of Much of the sun\’s direct radiation enters the room. Therefore, the combined use of these three methods has good effects and is more suitable for use in the temperate and tropical areas of the south. Its decorative effect can also be greatly increased when combined with tinted glass.

Editor\’s message:

Hello everyone, I am the editor Xiongda. I usually get asked a lot about doors and windows.As a major building material that is installed relatively early after the renovation begins, many owners are concerned about the quality of doors and windows. In addition to simple installation to avoid air leakage and water leakage, more and more owners are more concerned about the performance issues of heat insulation, sound insulation and energy saving of doors and windows. And these are inseparable from the properties of glass.

Thanks to Mr. Li from Yipin Xinge Doors and Windows for his professional guidance in writing this article. Compared with the high prices of foreign system doors and windows, Yipin Xinge’s system doors and windows are very affordable. They are A door and window manufacturer integrating R&D, design, manufacturing, sales and service of high-end doors and windows , currently their services mainly cover homeowners in Jiangsu, Zhejiang and Shanghai. I asked them to open the \”Yipin Xingge \”Decoration Information\” Readers Group\” for our readers. In less than half a month, there are nearly 20 people in the group. 2 people chose their products, and some Suzhou readers went to visit their factory. If you want to know more about the performance and price of their products or want to inquire more about doors and windows, you can send a private message to the editor and reply to Yipin, and I will add you to the group.