Code Description U-Value R-Value Solar Heat Gain Visible Light Transmittance
Clear Dual Dual pane, clear glass, no coatings 0.480 2.084 0.760 81%
Clear Tri Triple pane, clear glass, no coatings 0.310 3.226 0.685 74%
LOW-E HS1-C180 Dual pane, one Low-E coating, Argon 0.260 3.846 0.685 79%
LOW-E HS2-C180 Triple pane, one Low-E coating, Argon 0.184 5.433 0.615 73%
LOW-E HS3-C180 Triple pane, two Low-E coatings, Argon 0.133 7.521 0.560 70%
SUNSTOP HS4-C270 Dual pane, one SunStop coating, Argon 0.248 4.033 0.367 70%
SUNSTOP HS5-C270 Triple pane, one SunStop coating, Argon 0.186 5.377 0.338 63
SUNSTOP HS6-C270 Triple pane, two SunStop coating, Argon 0.124 8.065 0.310 54
SYSTEM V HS1V-C180/i89 Dual pane, two Low-E coatings, Argon 0.209 4.783 0.623 77
SYSTEM V HS4V-C270/i89 Dual pane, one Low-E & one SunStop coating, Argon 0.200 4.998 0.361 69

Values are in IMPERIAL. All performance for C.O.G. (centre of glass) ratings are based on Vision v4.0 simulations. All C.O.G U- and R-values are based on ASHREA Winter Conditions. Framing, cladding, frame type and other items will affect the overall thermal values of a complete window.

U-Value: A measure of the rate of nonsolar heat flow through a material or assembly. The lower the U-Value, the greater a window’s resistance to heat flow and the better its insulating value.

R-Value: A measurement of the resistance of heat transfer through the glass. The higher the R-Value, the better the window insulates against heat.

Solar Heat Gain (SHGC): The amount of the sun’s heat that transfers through glass from the exterior to the interior side. The higher the solar heat gain, the more a window allows heat to pass through into a home.

Visible Light Transmittance: measures how much of the visible light is entering the building through the glass. 1.0 would mean all of the light was getting through and 0 would mean none of it was getting through. Our atmosphere naturally filters out 5% of the visible light. Clear glass with no coatings lets in approx. 90% of visible light.