2. What is the shading coefficient Sc and what part of heat transfer does it reflect? Shading coefficient Sc: ratio of solar radiant energy through glass to solar radiant energy through 3mm transparent glass under the same conditions. Solar radiation through 3mm transparent glass can reach 630w/m2.        

Shading coefficient Sc= direct solar radiation energy ÷630w/m2

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

3. Is Sc high or low? Different shading coefficients of the glass are suitable for different climates. Sunshade coefficient is high, the solar radiation that enters indoor through vitreous window is much, reduce heating cost in winter thereby. This kind of glass is suitable for the long winter in northern areas. Low shading coefficient, good blocking effect on direct solar radiation, can reduce the direct solar radiation energy into the room. This kind of glass is suitable for the long summer in the south.

4.What is U? What part of the heat transfer does it reflect? The U value reflects the heat energy that passes through the glass due to convective conduction, including the heat energy that is absorbed by the glass and then transmitted to the outside. Therefore, if the emissivity of the glass is low, the U value is correspondingly low. Heat energy of convection conduction =U value × (T outdoor -T indoor) T outdoor and T indoor are indoor and outdoor temperatures respectively.

5.What are the components of the total heat energy transferred through glass? How do I represent it? Composed of two parts: direct solar radiation heat transfer, convection conduction heat transfer. The formula can be expressed as: Q total =630×Sc+U× (T outdoor -T indoor)

6.What are the components of solar radiation? Consists of three parts: ultraviolet radiation, wavelength range of 0.01 ~ 0.38 micron. The wavelength of visible light ranges from 0.38 to 0.75 micron. Near infrared radiation, wavelength range 0.75 ~ 3 micron.

7.Does the far-infrared thermal radiation come directly from the sun? Far infrared thermal radiation comes from the sun indirectly. This part of energy is thermal energy, which is radiated from the sun to the object after it is absorbed by the object. Its wavelength ranges from 3 to 40 microns. In summer, far infrared thermal radiation emitted by outdoor roads and buildings under sunlight is one of the main sources of heat.

8.Is there far infrared thermal radiation in the room? Yes, indoor far infrared heat radiation comes from heating, household appliances, furniture, stove and human body after being irradiated by sunlight, which is the main heat source from indoor in winter.

9.How does far infrared thermal radiation pass through the glass? Far infrared thermal radiation can not be directly transmitted through ordinary glass, can only be absorbed or reflected by glass. The glass absorbs this part of energy and then the temperature rises, and loses this part of energy by convection with the air and sending out thermal radiation to both sides. Therefore, this part of energy eventually passes through the glass, but in the way of absorption and radiation.

10.How to distinguish far infrared thermal radiation from near infrared radiation? Near-infrared radiation, which comes directly from the sun, is not heat-sensitive, but can be converted into heat when absorbed by objects. Far infrared thermal radiation, as a result of solar energy conversion or artificial production, is itself heat. During the summer, look at the road under the sun, and you can see the wave of thermal radiation rising from the ground (that is, the solar energy is being converted into thermal radiation). Near the central heating in winter, you can directly feel the thermal radiation.

11 what is low-e glass? Low-e glass is low-radiation glass, which is coated on the surface of the glass, so that the radiation rate of the glass E is reduced from 0.84 to below 0.15.

12 what are the features of low-e glass? Low-e glass has the following characteristics: high infrared reflectance, can directly reflect far infrared thermal radiation. ★ the surface emissivity E is low, the ability to absorb foreign energy is small, thus radiating out less heat. ★ sunshade coefficient Sc has a wide range, which can control the amount of solar energy transmission according to the needs, so as to adapt to the needs of different regions.

13.Why does the low-e membrane reflect heat? The low-e film is coated with silver, which can reflect more than 98% of the far-infrared thermal radiation out, thus directly reflecting heat as a mirror reflects light. Low-e's shading coefficient Sc ranges from 0.2 to 0.7, allowing direct solar radiation into the interior to be regulated as needed.

What is heat-reflecting glass? Thermal reflection glass is usually said to be coated glass, it is coated on the surface of the glass, so that the glass shading coefficient Sc from 0.98 (6mm transparent glass) to 0.2 ~ 0.6 formed.

14.What are the functional differences between low-e glass and heat-reflecting glass? Heat reflection glass can reduce the cost of air conditioning and save energy by reducing the shading coefficient of the glass and limiting the direct radiant energy of the sun to enter the room through the glass. Low-e glass is to reduce the U value of the glass, limit the far infrared thermal radiation through the glass, so as to achieve the goal of reducing the convection conduction heat energy through the glass. At the same time, low-e glass shading coefficient Sc adjustment range is large, can effectively control the direct solar radiation into the room.

15.What are the main types of mature coated glass processes? There are two main types: on-line coating and vacuum magnetron sputtering coating (also known as off-line coating). The on-line coated glass is made in the float glass production line. This kind of glass has single variety, poor thermal reflection performance and low manufacturing cost. Its only advantage is that it can be hot - bent machining. The coated glass made by vacuum magnetron sputtering process is rich in variety, excellent in thermal reflection and obvious in energy saving. Its disadvantage is not hot bending machining.

16.Can low-e glass be used as a single piece? Low-e glass made by vacuum magnetron sputtering process can not be used as a single piece, but can only be used as synthetic insulating glass or laminated glass. But its emissivity E is far lower than 0.15 and can be as low as 0.1. Low-e glass made by online coating process can be used as a single piece, but its emission-rate is E=0.28, which is no longer technically called low-e glass (objects with a emission-rate of E£0.15 are scientifically referred to as low-radiation objects). Low-e glass is most effective in a similarly enclosed space formed in a sealed insulating glass, which eliminates the flow of air on the low-e surface, thus enabling the low-e glass to function better.

18.Does low-e glass perform the same? From a technical point of view, all low-e glasses treat spectral curves in the same way, but not all have the same properties.

19.Does all low-e glass look the same? Not the same! Some low-e looks high transparency, the penetration rate is more than 60%, and the color is light. Some low-e looks Low transparency, the penetration rate is less than 55%, and the color is relatively dark.

20.Does the low-e glass night still work? Is!!! Low-e glass works day and night. In winter, day and night will reflect heat (far-infrared thermal radiation) back into the room, because both heat generated by heating and solar energy are in the form of far-infrared thermal radiation.

21.How does low-e glass work in summer and winter? In winter, indoor temperature is higher than outdoor temperature, and far-infrared thermal radiation mainly comes from indoor, low-e glass can reflect it back into the indoor so as to keep the indoor heat. The low-e glass still allows some of the solar radiation from the outside to enter the chamber, which is absorbed by the objects inside and then converted into far-infrared thermal radiation, which is kept inside. In summer, the outdoor temperature is higher than the indoor temperature, and the far-infrared thermal radiation mainly comes from the outside. Low-e glass can reflect it out and prevent the heat from entering the room. For solar radiation from outside, low-e glass with Low shading coefficient can be selected to limit its entry into the room, thus reducing cooling cost (air conditioning cost).

22 on which surface of the insulating glass is the low-e film most suitable? Insulating glass has 4 surfaces, and the number from outdoor to indoor is 1 #, 2 #, 3 # and 4 # surfaces respectively. Where the heating demand exceeds the cooling demand (in the northern region), the low-e film is located on the surface of no. 3. Conversely, where cooling needs exceed heating needs (in the southern region), the low-e membrane layer should be located on the surface of no. 2.

23.What role does argon gas fill in hollow glass? Argon is a kind of inert gas, its heat transfer performance is worse than air, so filling into insulating glass can reduce the U value of insulating glass and increase the insulation of insulating glass. Argon can also protect low-e insulating glass.

24.What are the negative effects of ultraviolet radiation? Ultraviolet radiation, which is invisible to the naked eye, accounts for about 2 percent of the total energy emitted by the sun. Ultraviolet rays can kill bacteria, but prolonged exposure can burn people's skin and eyes, and discolor furniture and clothing.

25 how much uv can low-e glass attenuate? Low-e glass can reduce uv rays by 25 per cent compared to ordinary one-piece transparent glass. Low-e glass can reduce ultraviolet radiation by 14 percent compared to heat-reflecting coated glass. Low-e glass can not completely avoid furniture fading, but can slow down the fading.

26.How does low-e glass affect indoor plants? It has no adverse effect on most common plants. For special rare plants, you may consult a flower expert.

27.Do sunshades, 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, which blocks some solar energy from passing through, but does not affect the performance of low-e glass.

28.Which direction is the best to install low-e glass? In winter, no matter which direction the low-e glass faces, it does not affect its function, because it mainly reflects the indoor heat. But it works best when installed in a northerly direction. Low-e glass, after all, limits solar radiation somewhat while preventing indoor heat loss. In summer, low-e mainly reflects outdoor heat, so it is suitable for installation in either direction. However, installation in the east, west and south direction is the best, because it can also reduce the penetration of solar energy.

29 how long does the low-e membrane last? The duration of the coating layer is the same as that of the insulating glass space layer.

30.What is the effect of the combination of 30low-e glass and tinted glass? There are three ways to combine: coating low-e film on tinted glass, synthesizing hollow glass with tinted glass, and synthesizing laminated glass with tinted glass can further reduce the shading coefficient of composite glass products, thus limiting more direct solar radiation into the room. Therefore, the combined use of these three methods is very good, more suitable for the southern temperate tropical areas. Combine with coloured glass to use still can increase its adornment effect greatly.

 

 

(source: green energy weathervane)