Curtain wall introduction|30 common problems with curtain wall glass

Direct solar radiation energy = 630w/m2×Sc The shading factor reflects the heat transfer of direct solar radiation through the glass.

3 Is it better to have a high or low shading coefficient Sc?

Glass with different shading factors is suitable for different climates. The shading factor is high, and there is more solar radiation entering the room through the glass window, thereby reducing the heating cost in winter. This glass is suitable for use in northern regions with long winters. The shading factor is low, and the blocking effect on direct solar radiation is good, which can reduce the direct radiation energy of the sun entering the room. This glass is suitable for use in the southern regions with long summers.



4 What is U-value? Which part of the heat transfer does it reflect?

The U-value reflects the heat energy that passes through the glass due to convective conduction transfer, including the transfer of heat energy absorbed by the glass and then radiated outward. Therefore, the emissivity of glass E is low, and the U value is correspondingly low. Convective conductive heat energy = U value × (T outdoor-T indoor) T outdoors and T indoors are indoor and outdoor temperatures respectively.



5 How many parts are there in the total heat energy transferred through glass? How to express it?

It consists of two parts: direct solar radiation heat transfer and convective conduction heat transfer.

It is expressed as Q total = 630×Sc+U× (T outdoor--- T indoor)
6 What are the components of solar radiation?

It consists of three parts: ultraviolet radiation, wavelength range 0.01~0.38 microns. The visible light wavelength range is 0.38~0.75 microns. Near-infrared radiation, wavelength range 0.75~3 microns.


7 Does far-infrared thermal radiation come directly from the sun?

Far infrared thermal radiation is indirectly from the sun, this part of the energy is thermal energy, which is radiated by the sun on the object and absorbed by the object, and its wavelength range is distributed in the wavelength range of 3~40 microns. In summer, the far-infrared heat radiation emitted by outdoor roads and buildings under sunlight is one of the main heat sources from outdoors.


8 Is there far-infrared heat radiation indoors?

Yes, indoor far-infrared heat radiation comes from heating, household appliances, furniture exposed to sunlight, stoves and the human body, which is the main heat source from indoors in winter.



9 How does far-infrared thermal radiation pass through glass?

Far infrared heat radiation cannot directly transmit through ordinary glass, but can only be absorbed or reflected by glass. After the glass absorbs this energy, the temperature rises, and this part of the energy is lost through convection conduction with air and heat radiation to both sides, so this part of the energy eventually passes through the glass, but it is absorbed first and then radiated.


10 How to distinguish between far-infrared thermal radiation and near-infrared radiation?

Near-infrared radiation comes directly from the sun and its heat sensation is not obvious, but it can be converted into heat after being absorbed by objects. Far-infrared thermal radiation, as a result of solar energy conversion or human production, is itself heat. In summer, observing the road under the sun can see heat radiation waves rising from the ground (i.e., solar energy is being converted into heat radiation). In winter, you can directly feel the heat radiation near the heating.


11 What is Low-E glass?

Low-E glass is low-emissivity glass, which is formed by coating the glass surface to reduce the emissivity E of the glass from 0.84 to less than 0.15.

What are the characteristics of 12 Low-E glass?

Low-E glass has the following features:

★ High infrared reflectivity can directly reflect far infrared thermal radiation.

★ The surface emissivity E is low, and the ability to absorb external energy is small, so the heat energy is less radiated.

★ The wide range of shading coefficient Sc can control the transmittance of solar energy according to the needs of different regions.


13 Why does Low-E film reflect heat?

The Low-E layer is coated with a silver layer, which reflects more than 98% of the far-infrared heat radiation, so that the heat is reflected directly like a mirror reflecting light. The shading factor of Low-E can be from 0.2 to 0.7, so that the direct solar radiation energy entering the room can be adjusted as needed.

14 What is Heat Reflective Glass?

Heat-reflective glass is commonly referred to as coated glass, which is formed by coating the surface of the glass to reduce the shading coefficient Sc from 0.98 (6mm transparent glass) to 0.2~0.6.

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

Heat reflective glass reduces the shading coefficient of the glass and limits the direct radiation energy of the sun to enter the room through the glass, so as to reduce the cost of air conditioning and save energy. Low-E glass reduces the U-value of the glass and limits the transmission of far-infrared heat radiation through the glass, thereby reducing the convective conduction of heat energy through the glass. At the same time, the shading coefficient Sc adjustment range of low-E glass is large, which can effectively control the direct radiation energy of the sun entering the room.
16 What are the main types of mature coated glass processes?

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

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

Low-E glass manufactured by vacuum magnetron sputtering process cannot be used as a single piece, but can only be used as synthetic insulating glass or laminated glass. But its emissivity E is much lower than 0.15, and can be as low as 0.1. Low-E glass made by the in-line coating process can be used as a single piece, but its emissivity E=0.28 is no longer strictly called Low-E glass (scientifically an object with an emissivity of E £0.15 is called a low-emissivity object). Low-E glass is most effective in similar enclosed spaces that form in sealed insulating glass, as this enclosed space eliminates air flow on the Low-E surface, allowing Low-E glass to function better.

18 Does Low-E glass perform the same?

From a technical point of view, all Low-E glasses process the spectral curve in the same way, but not all perform the same.

19 Do all Low-E glass look the same?

It's different! Some Low-E appear to have high transparency, with a transmittance of more than 60% and a light color. Some Low-E appear to have low transparency, with a transmittance of less than 55%, and a relatively dark color.

Does 20 Low-E glass still work at night?

Be! Low-E glass works day and night. In winter, heat (far-infrared heat radiation) is reflected back indoors day and night, because both heat generated by heating and solar energy are converted in the form of far-infrared heat radiation.

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

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


22 Which surface of insulating glass is most suitable for the Low-E coating?

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



23 What is the function of filling argon in insulating glass?

Argon is an inert gas, its heat transfer is worse 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 effect of protecting the Low-E film layer.

24 What are the negative effects of ultraviolet rays?

Ultraviolet light is shortwave radiation, invisible to the naked eye, and it accounts for about 2% of the total energy of solar radiation. UV rays can kill bacteria, but prolonged exposure can burn human skin and eyes, and can also fade furniture and clothing.


How much UV light does 25 Low-E glass attenuate?

Compared with ordinary monolithic clear glass, Low-E glass can reduce UV rays by 25%. Compared to heat-reflective coated glass, Low-E glass reduces UV rays by 14%. Low-E glass does not completely prevent fading of furniture, but it slows down fading.


26 How does Low-E glass affect indoor plants?

There is no adverse effect on most ordinary plants, and the impact on special rare plants can be consulted with relevant flower experts.



27 Do shades, trees and awnings affect the performance of Low-E glass?

These objects can limit the heat and light entering the room through the glass window, i.e. block some of the solar energy from penetrating, but do not affect the performance of low-E glass.


28 Which direction is the best way to install Low-E glass?

In winter, Low-E glass does not affect its function regardless of the direction it is facing, as it mainly reflects heat from the room. However, it works best when installed facing north, after all, Low-E glass prevents indoor heat loss while also limiting solar radiation. In summer, Low-E mainly reflects outdoor heat, so it is suitable for installation in any direction, but it works best when installed in the east, west, and south directions, as it also reduces the transmission of solar energy.


29 How long does the Low-E coating last?

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


What is the effect of combining 30 Low-E glass with tinted glass?

There are three ways to combine it: Low-E film on tinted glass, insulating glass synthesized with tinted glass, and laminated glass with tinted glass Tinted glass can further reduce the shading factor of combined glass products, thereby limiting more direct solar radiation into the room. Therefore, the combination of these three methods is very effective and is more suitable for use in southern temperate tropical regions. In combination with tinted glass, it also greatly increases its decorative effect.