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Thermal Performance Data 
| Product | Total Unit U-Factor
| Total Unit SHGC
| Visible Light Transmittance
| UV Block
|
The Horizon, Yellowstone or PrimeLok Single Hung
Clear
Low E and Air (Average) |
0.49
0.34
|
0.59
0.31 |
82%
57%
|
42%
84%
|
The Solaris, Yosemite, or PrimeLok Double Hung
Clear
Low E and Air (Average)
|
0.49
0.35 |
0.58
0.30 |
82%
54%
|
42%
84%
|
The Horizon, The Solaris, Yellowstone, Yosemite or PrimeLok Single Slider
Clear
Low E and Air (Average)
|
0.49
0.34 |
0.55
0.31 |
82%
56%
|
42%
84%
|
The Horizon, The Solaris, Yellowstone, Yosemite or PrimeLok Picture Window
Clear
Low E and Air (Average) |
0.49
0.33
|
0.62
0.32 |
82%
59%
|
42%
84%
|
The Eclipse, Grand Mesa or TruLok
Clear
Low E and Air (Average)
|
0.49
0.35
|
0.58
0.30
|
82%
54%
|
42%
84%
|
The Solstice, Grand Teton or GrandLok
Clear
Low E and Air (Average)
|
0.49
0.35
|
0.58
0.30
|
82%
54%
|
42%
84%
|
The Aurora or Cascades Casement / Awning
Clear
Low E and Argon (Average)
|
0.45
0.31
|
0.56
0.31
|
82%
72%
|
42%
84%
|
Terminology
Emissivity is a measure of a surface's ability to emit long-wave infrared radiation or room temperature radiant heat energy. Emissivity varies from 0 (no emitted infrared) to 1 (100% emitted infrared). The lower the emissivity, the lower the resultant U-Value.
U-Value is the amount of heat transmitted by the window. The lower the number, the more efficient the window is in reducing winter heat loads and costs. Expressed in Btu/hr.ft2.F.
R-Value designates a window's resistance to heat flow. This number is the inverse of the U-Value: the higher the number, the more efficient the window in reducing winter heating costs. Expressed in hr.ft2.F/Btu.
Solar Heat Gain Coefficent is the fraction of incident solar radiation entering a home through the windows. The lower the number, the better the window is at preventing solar gain - critical to reducing summer cooling costs.
