TSER,Only Factor To Evaluate Window Performance?

From:Linshang     Time:2015/8/13 12:01:19     Browse:

Many customers of Shenzhen Linshang Technology Co. , Ltd. inquired if there is any meter may test TSER or SHGC?
TSER(i.e.Total Solar Energy Rejection)means while sunlight irradiate on the glass, rejected rate of sun energy.  And SHGC=Solar Heat Gain Coefficient) means while sunlight irradiate on the glass, transmitted rate of sun energy. Let’s get started to study TSER, SHGC can calculated with the same method.
First, The ratio of the sun to the surface of the earth is about 53% infrared, 44% visible, and 3%.
For example of  V-KOOL 70,
VL transmittance: 70%     IR Rejection:  94%    UV Rejection:   99%
So let’s find how is TSER been calculated.

V-KOOL 70
Item
A
B
C
D
1

VL
IR
UV
2

VL transmittanceIR RejectionUV Rejection
3
Measured data70%94%99%
4
Transfer to Rejectionapproximate at30%94%99%
5
Proportion in sunlight44%53%3%





TSER=B4*B5+C4*C5+D4*D5=44%*30%+53%*94%+3%*99%=13.2%+49.82%+2.97%=65.99%.
It seem that TSER of V-KOOL 70 is 65.99%. But the answer is NO.

From the above picture, we can see that sun energy reject curve of spectrum is not horizontal line, so TSER=65.99% is not right, accuracy TSER data should use expensive spectrograph to measure every point and accumulated. in fact, that's why TSER data of V-Kool 70 is about 55%
UV rejection of most of solar film usually more than 90%, Just since the IR rejection is different, so caused the difference in the temperature of the car. So IR rejection is most main factor that effect the temperature of the car.
Moreover, Proportion in sunlight is not absolutely stable at different time interval.
The most important is Total Solar Energy Rejection need to consider of the convection and conduction after  absorbed.
For above reasons, it is very hard to get accuracy TSER data, it’s estimated data,just for reference.
Our
Solar Film Transmission Meters and Spectrum Transmission Meter elected 950nm and 1400nm as IR wavelength test point, which adaptable to most popular solar films on market, upgrade products with parallel light source, limit test error in +/-2% which is enough for  film customer.

Related Articles Link