Ultraviolet blocking function of low-E coating

 Ultraviolet was discovered in the early 19th century and generally refers to light radiation with a wavelength of 100 nm to 380 nm. Ultraviolet radiation is a double-edged sword to human life. UV protect people but too much UV will be harmful.

 Low-E glass is more and more widely used, but people are more concerned about the blocking effect of Low-E glass on infrared radiation, and seldom care about its block function of ultraviolet rays. This article introduces the effects and effects of ultraviolet rays on the human body and objects, discusses the attenuation of Low-E glass to ultraviolet rays, and gives suggestions.

solar energy -Ultraviolet

The function &influence of Ultraviolet

1. 
   

   The influence on human body

Appropriate amount of ultraviolet rays are helpful to human body, it can promote the production of vitamin D. and promote the absorption of calcium.However,if the human body is exposed to excessive ultraviolet rays,a series of changes in the body, causing damage to the eyes, skin, immune system, etc.

UV effect on human body

2. 
   

   The influence on bamboo and wood

The main components of bamboo and wood materials such as cellulose and hemicellulose absorb ultraviolet rays to a certain extent. After absorption, the molecular structure will be damaged, and its physical and chemical properties will also be seriously affected, which ultimately affects the stability,Performance, durability, aesthetics of bamboo and wood materials.

long time sunlight cause furniture fading

3. 
   

   The influence on Polymer Materials

Polymer materials include plastics, rubber, fibers, films, adhesives and coatings, etc., which are widely used in indoor furniture and installations. When polymer materials are irradiated with light, the molecular chain of the material is broken, the physical and mechanical properties are deteriorated, and the chemical structure is changed, thereby partially losing or losing its use value, and appearing hard, sticky, brittle, discolored, and losing strength.

Resin roof color fading

The UV blocking effect of normal insulated glass

The GlassSpec2500 building glass spectrophotometer is used to measure the ultraviolet transmission of common glass. The measuring wavelength range of this instrument is 300nm～2500nm. It can directly measure the ultraviolet transmittance of insulated glass without destroying the glass structure.

GlassSpec2500 Spectrophotometer

Before the test we must be clear that UVC comes from manual lighting,other UV brands-UVA (wavelength 315-380nm) and UVB (wavelength 280-315nm) can penetrate the glass,Below is the test result:insulated glass (6+12A+6)  made with clear glass can block 52.56% UV,clear glass can block 100% UVB (wavelength 280nm-315nm) and low iron insulated glass block 24.48% UV,but allows 28% UVB transmission.

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Glass type	Glass structure	UV transmittance %	UVA transmittance	UVB transmittance
Clear Insulated glass	6+12A+6	47.44%	48.78%	0%
Low iron insulated glass	6+12A+6	75.52%	76.86%	28.13%

The UV blocking effect of low e insulated glass

Below table shows the UV transmission of single silver low-E,double silver low-E and triple silver low-E.

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Glass type	Glass structure	UV transmittance %	UVA transmittance	UVB transmittance
Single silver lowe	6 low-e+12A+6	32.38%	33.29%	0%
Double silver lowe	6 low-e+12A+6	15.11%	15.53%	0%
Triple silver lowe	6 low-e+12A+6	8.43%	8.67%	0%

Conclusion:

The ultraviolet rays blocking effected is sorted from strong to weak: triple silver low e IGU> double silver low E IGU> single silverLow e IGU> clear insulated glass > low iron insulated glass.Low-E insulating glass can block more ultraviolet rays and reduce the incidence of ultraviolet rays into the room.

UV transmittance of different insulated glass

In practical applications, we can change the transmittance of the Low-E film in various bands by changing the thickness of the Low-E coating to further affect the UV transmittance. The thicker the Low-E film, the stronger block effect.

Is it necessary to consider the UV blocking of Low-E glass ?

In the current scientific cognition, UVA has not yet found its direct benefit to the human body, that is, no matter how much Low-E glass attenuates ultraviolet rays, the human body cannot benefit from the ultraviolet radiation passing through the glass.

The short-wave part of UVB also has a sterilization effect,but only low iron glass allows UVB transmittance, clear glass blocked 100% UVB.

No matter how much the UV transmittance ,the UV transmitted through Low-E insulated glass don’t play the role of disinfection and sterilization.

Soaking up the sun in front of indoor glass windows is far less effective than outdoors.

outdoor sunlight

When indoor bamboo and wood materials and polymer materials (plastics, paints, etc.) are used frequently, attention should be paid to the attenuation of ultraviolet rays when choosing Low-E glass, and the ultraviolet rays entering the room should be minimized.

For museums and libraries, in order to reduce the impact of ultraviolet rays on cultural relics, books, calligraphy, etc., it is necessary to consider the attenuation of Low-E glass to ultraviolet rays,in this case,laminated insulated glass will be perfect which can not only block 100% UV but also offering good thermal insulation performance.

Library should avoid UV rays transmission

Morn is your turnkey insulated glass manufacturer and supplier in China,we offer high UV blocking insulated glass,especially triple silver low-E insulating glass with high performance,welcome contact us if you got any projects require UV block glass.

Download this article here:Ultraviolet block function of low-E coating

20 FAQ about low emissivity glass-Glass Guidance

 

1. What’s the component of solar radiation?

The solar radiation include 3 parts: UV radiation (Wavelength range 0.01～0.38 microns),visible light (Wavelength range 0.38～0.75 microns),near infrared radiation(Wavelength range 0.75～3 microns).

2. 
   

   What’s the difference between near infrared radiation and far infrared radiation?

Near-infrared radiation comes directly from the sun, and its heat is not obvious, but it can be converted into heat after being absorbed by an object.Near infrared radiation cannot transmit the glass directly,it can be only been reflected or absorbed by the glass,after glass absorbing the near infrared radiation,glass temperature will increase and become a radiation source itself.

Far infrared is a result of solar energy conversion or artificial production,such as the stove,house appliance, human body,and the furniture that lighted by the sun.In summer,the exterior road,buildings are the main source of far infrared after lighted by the sun.

3. 
   

   What kind of thermal that are transferred through glass?

The energy that transferred through glass include direct solar radiation ,typical parameter to measure it is glass SC (Shading coefficient) and SHGC (Solar heat gain) .

The 2^nd part is convection conduction of heat transfer.It’s related to the infrared radiation. U value is the parameter to measure ,and measurement are W/m²K.

Transfer heat from a high-temperature object to a low-temperature object: heat conduction, heat convection, and thermal radiation.

4. 
   

   What’s glass SC ?

 

Glass SC is to measure the UV & visible light solar radiation transmitted the glass.

Glass SC is short for glass shading coefficient,which means Under the same conditions, the ratio of the solar radiant energy through the glass to the solar radiant energy through the 3mm transparent glass. The solar radiation energy through 3mm transparent glass is 630w/m2.

The higher SC value,the more solar radiation penetrated the glass to decrease heating costs in summer,it’s widely used in long winter areas.

The lower SC value,the better blocking effect of direct solar radiation and reduce the solar radiation energy entering the room,suitable for hot areas.

 

5. 
   

   What’s glass U value?

 

The heat energy transmitted through the glass due to convection conduction, includes the transmission of heat energy after the glass absorbs the heat energy and then radiates outward&inward. Therefore,lower emmissivity,the lower U value.

6. 
   

   What’s low e glass?

Low e glass is short for Low emissivity glass,is to have a multi layer coating composing metalic &chemical on glass surface to decrease the glass emissivity ratio from 0.84 to below 0.15,or even only 0.03.The typical emissivity of low e glass include single silver low-E,double silver low-E and triple silver low-E,which contains 1 layer, 2layer,and 3 layers silver coatings.Hard coated low e glass as relatively higher emissivity compared with the soft coated low e.

Hard coated low e VS Soft coated low e

Difference between Single silver low-E,double silver low e and triple silver low e

coating layer-single-double-triple silver lowe coating

7. 
   

   What’s the function of the low-E coating?

The feature of low e coating is thermal insulation.

The low emissivity coating can reflect the far infrared radiation directly,especially the silver layer inside the soft coated low-E coating can reflect 98% far infrared radiation like mirrors.

The coating has little capability absorbing the heat,which will control the glass surface temperature very well, the heat re-radiated out from the glass is little accordingly.

Despite controlling the infrared,the coating as a variety options with different visible light transmittance and SC value(0.2-0.7)  to control the ratio of direct solar energy transmitted through the glass,which can be selected by users both in hot and cold areas.

insulated glass-heat transfer-morn bm

 

8. 
   

   What’s the difference between solar reflective glass and low e glass?

 

Solar reflective glass reduces the shading coefficient of the glass and restricts the direct solar radiation from 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 to restrict the far-infrared radiation from penetrating the glass,in addition, the shading coefficient has a large adjustment range, which can effectively control the direct solar radiation energy entering the room.

 

9. 
   

   What’s the mature coating types of low e glass?

 

There’re 2 kinds of low e glass,soft coated low e coating and hard coated low e coating.

Hard coated low e glass is manufactured on a float glass production line. This type of glass has a single variety, poor heat reflection performance. Its only advantage is that it can be used as monolithic glass or been laminated.

Soft coated low e glass is manufactured by the vacuum magnetron sputtering process .It has a variety of colors, excellent heat reflection performance, and obvious energy-saving characteristics. The disadvantage is that it must be made into insulated glass,or the coating will be oxidized once exposed in the air.

 

10. 
    

    Does low e glass wok at night?

 

Yes,low e glass work anytime.No matter what kind of far infrared,whether it’s caused by the solar,or artificial far infrared,it can always reflect the infrared heat.

 

11. 
    

    How does low e coating works in summer and winter?

 

In winter, the indoor temperature is higher than outdoors, and the far-infrared heat radiation mainly comes from indoors. Low-E glass can reflect it back indoors to keep indoor heat from escaping.

In summer, the outdoor temperature is higher than indoors, Low-E glass can reflect the exterior heat out to prevent heat from entering the room. For outdoor solar radiation, Low-E glass with low shading coefficient can be selected to restrict its entry into the room, thereby reducing cooling costs.

12. 
    

    Low-E coating on surface #2 or surface #3?

Insulating glass has 4 surfaces, the number from outdoor to indoor is 1#, 2#, 3#, 4# surface.

In areas where the heating demand exceeds the cooling demand , the Low-E film layer should be on surface #3.  Conversely, in areas where cooling demand exceeds heating demand (southern areas), the Low-E film should be on the 2nd surface.

Low e coating position-Surface #2 VS Surface #3

low e coated glass -morn-china-manufacturer-morn

13. 
    

    What’s the function of argon filled in insulated glass?

 

Argon is an inert gas, and its heat transfer performance is worse than air. Therefore, argon filled insulated glass will have better thermal insulation,lower U value, argon also protect the Low-E film.

 

14. 
    

    How much Uv the low-e coating can block?

 

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

 

Low-E glass can reduce ultraviolet rays by 25%. compared with clear glass, It cannot completely avoid furniture fading, but it can slow down the fading.

 

15. 
    

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

 

These objects can restrict the heat and light entering the room through the glass window, that is, block part of the solar energy from passing through, but it does not affect the performance of Low-E glass.

insulated glass with frosted glass effect-MORN -CHINA

16. 
    

    Is the windows&glass installation angle affect the glass U value?

Yes,the glass U value and shading coefficient are not affected by the installation angle,while in winter,the glass U value increase significantly with the angle from 90degress to 0 degrees.So for glass roofs,skylights,please select a low e coating with better U value.

How the glass U value been affected by the installation angle?

The double glazed unit used in glass skylight should be toughened glass or heat strengthened glass.The inner pane may be toughened or laminated GLASS.

17. 
    

    What’s the effect combing the low e coating with body tinted glass?

 

There’re 3 kinds of combinations:

Coating directly on body tinted glass, clear low e glass + body tinted insulated glass, laminate body tinted glass with clear low e coated glass.

Tinted glass can further reduce the shading coefficient,thereby restricting more direct solar radiation from entering the room. Therefore, the combined effect of these three methods is very good, and it is more suitable for use in tropical regions. Combining with colored glass can also greatly increase its decorative effect.

But do pay attention that coating on tinted glass price is higher ,also contains many advantages and disadvantages.

glass curtain wall with tinted glass insulated glass-morn-china

18. 
    

    What’s the lifetime of low e coating?

Hard coated low e glass lifetime is same as the glass lifetime.

Soft coated low-E glass,after unpack the glass package,it’s suggested to make into insulated glass asap,or the coating will be damaged or oxidized within 30 days or even shorter time.

Once been made into insulated glass,the coating lifetime is same as the glass sealing time.

 

19. 
    

    Where can we buy high performance low e coated glass?

Hard coated low-E manufacturers in China include AGC, Jinjing, SYP,Kibing.

Hard coated low e options in China

As Soft coated low-E must be made into insulated glass,it’s suggested to purchase finished insulated glass with high performance low e coating directly,Morn glass is your turnkey coated glass supplier,our products include single,double and triple silver low e insulated glass,click below link to check our coated glass performance data:

W1.1 and W1.16 low E coating for greenhouse /conservatory

Morn-Coated glass performance data

Morn-Triple silver low-E glass performance data

triple silver low-E coated glass-solarban 70XL-CHINA

20. What’s low e coated glass price?

The glass price varies based on different project requirement,generally the glass combination,glass size,materials used in the insulated glass ,and many other factors-glass packing,broken&replacement,shipping costs affect the final insulated glass price.

 

Need more help? Contact us through marketing@cnmorn.com, our glass expert are ready to serve you.

Download this article here:20 FAQ about low emissivity glass-Glass Guidance