Solar transmission properties – Palram PALSU User Manual
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Solar Transmission Properties
Solar energy transmission is an extremely important consideration
with transparent materials. Geographic location and typical thermal/
optical properties of the specific glazing are the main factors
influencing solar heat gain. Various types of PALSUN - textured,
tinted, opal, diffused, and heat blocking SolarSmart™ sheets - can
be used to deliver the exact quantity and quality of light desired.
Each of these products transmit different amounts of direct light in
varying levels of light diffusion, which may help to spread the light
throughout the structure or enclosure. The sheets also vary in their
selectivity index (SI) values, which determines how efficiently they
keep heat out while letting more “cool light” in (See
for
more information on SolarSmart™ products). Although colors and
tints reduce the percentage of visible light transmitted through the
sheets, but solar energy is still absorbed by the glazing itself, and in
turn transferred by convection and far IR radiation from the heated
glazing into the building. PALSUN sheets with embossed or matte
surfaces, or diffuser colors, diminish glare and dazzle, preventing
damage by direct irradiance. However solar energy is still transmitted
through and increases the solar heat gain inside the structure.
Figure 4: Solar Radiation Schematic Behavior Through
Light Transmitting Material
Color*
% Light Transmission
ASTM D-1003
%Haze
ASTM D-1003
Solar Heat Gain (SHGC)
ASTM E-424-71
Shading Coefficient
ASTM E-424-71
Clear
90
<1
0.87
1.00
Bronze
20
<1
0.45
0.52
35
<1
0.56
0.64
50
<1
0.65
0.75
Solar Grey
20
<1
0.44
0.51
35
<1
0.56
0.64
50
<1
0.65
0.75
White Opal
28
100
0.32
0.37
White Diffuser
80
100
0.87
1.00
Solar Ice
20
100
0.37
0.45
Solar Control
20
67
0.33
0.36
35
52
0.45
0.52
50
50
0.54
0.61
Solar Olympic
20
35
0.41
0.47
35
20
0.52
0.60
50
63
0.63
0.73
Smart Green
70
42
0.58
0.67
Smart Blue
70
42
0.57
0.65
Bluish Breeze
70
42
0.55
0.63
*Values in the table above relate to 3mm Sheet. Further information on additional products is available upon request.
Terminology Used in the Table
Solar Radiation: The solar spectrum ranging from 300 nm to 2400 nm. Included are UV, visible and Near-IR radiation.
Visible Light Radiation: The portion of the light spectrum whose wavelength ranges from 400nm to 780nm.
% Light Transmission (ASTM D-1003): Percentage of incident visible light that passes through an object.
% Solar Heat Gain (SHGC): The percent of incident solar radiation transmitted by an object which includes the direct solar transmission plus the part of the solar
absorption reradiated inward.
Shading Coefficient (ASTM E424-71): The ratio of the total solar radiation transmitted by a given material to that transmitted by normal glass, whose light transmission
is 87%. It can be approximately calculated by: %ST + (0.27 x %SA) = %STt SC = (1.15 x STt)/100