Description |
UnitThickness |
R-Value (R=
1/U-Value) |
Shading |
Relative |
Visible |
Single Glazing |
.098 |
1.11 - n/a - n/a |
1.01 |
217 |
90% |
Double Glazing |
.697 |
2.04 - 2.17 - n/a |
.90 |
188 |
82% |
Low-E Sealed Unit |
.717 |
3.12 - 3.70 - 4.00 |
.69 |
143 |
77% |
Triple Low-e |
1.250 |
4.35 - 5.26 - 5.55 |
.64 |
131 |
70% |
Heat Mirror 88 |
1.200 |
4.35 - 5.26 - 5.56 |
.67 |
138 |
73% |
Heat Mirror TC88 |
1.200 |
5.56 - 7.14 - 7.69 |
.60 |
123 |
67% |
Heat Mirror SC75 |
1.200 |
4.76 - 5.88 - 6.25 |
.41 |
86 |
62% |
Heat Mirror 66 |
1.200 |
4.55 - 5.55 - 6.25 |
.44 |
89 |
56% |
Heat Mirror 55 |
1.200 |
4.76 - 5.56 - 6.25 |
.37 |
77 |
48% |
Heat Mirror 22 |
1.200 |
4.76 - 5.88 - 6.25 |
.16 |
35 |
20% |
Superglass 88 |
1.328 |
n/a - n/a - 9.09 |
.52 |
107 |
65% |
Superglass 66 |
1.328 |
n/a - n/a - 10.90 |
.28 |
57 |
41% |
data obtained using L.B.L. (Laurence Berkeley Laboratories) Window 4.1 analysis program (nfrc/ashae)
Glossary of terms used in the Insulated Glass performance table
| Unit Thickness the total overall thickness of the insulated glass unit. Please note that all units shown in the table indicate a 1/2 inch airspace between two lites of glass, or between each lite of glass a film, in the case of Heat Mirror products. 3mm (1/8 '') glass is used in all examples shown above. |
| *R-Value measures the insulation effectiveness of the glass. The higher the R-Value, the better the insulating performance. |
| Shading Coefficient measures the total solar heat gain through the glazing compared to 1/8'' clear glass under the same design conditions. It includes both the solar energy transmitted directly plus any absorbed solar radiation that is re-radiated as heat into the interior. The number ranges from 0.0 to 1.0 Standard insulating glass has an SC of 0.81. The lower the shading coefficient, the lower the heat gain. |
| Relative Heat Gain the total heat gain through the glass for a specific set of conditions. This value considers indoor/outdoor temperature differences and the effect of solar radiation. (English units = Btu/hr(ft2) |
| Light Transmittance the percentage of light transmitted through the window. The number ranges from 0 to 100%. Standard clear insulating glass has a daylight transmission of 82%. |
| Winter Nighttime windward: 6,7 mtr/sec. (15 mph), ext. temperature of - 18° Celsius( 0° F) int. temperature of 21° Celsius (70° F), without solar radiation. |
| Summer Daytime windward 3,4 mtr/sec. (7.5 mph) ext. temperature of 32° Celsius (89°F), de 24°C (75°F) solar radiation of 783 W/m² (248.3 BTU/(hr./ft.²) |
| Reflectance the percentage of either light of total solar energy that a glazing reflects to the outside (exterior daylight reflectance) of a building. The number ranges from 0 to 100%. Standard clear insulating glass has a reflectance of 16%. |
| U Value measures the heat loss or grain due to differences between indoor and outdoor air temperatures (English units=Btu/hr ft² F°). The U-value equals one divided by the R-value. the lower the U-value, the better the insulating performance. Unless noted, calculations are for the center of insulating glass units; edge effects and window system frames have not been considered and will influence actual overall insulating performance of the window system. |
| Shading Coefficient measures the total solar heat gain through the glazing compared to 3 mm (1/8") clear glass under the same design conditions. It includes both the total solar energy transmitted directly plus any absorbed radiation that is re-radiated as heat into the interior. The number ranges from 0.0 to 1.0. The lower the shading coefficient, the lower the solar heat gain. |
| Relative Heat Gain the total heat gain through the glass for a specific set of conditions. This value considers indoor/outdoor temperature differences and the effects of solar radiation. |