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

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.