Green Commitment
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Energy Performance Window Performance
Measuring Window Performance
The optional SolarZone™ Insulated Glass Package combines multi-layered, vacuum deposition Low-E Glass with argon gas and a Warm-Edge spacer system. These insulated glass packages have proven to be far more effective than ordinary clear glass units. The National Fenestration Rating Council (NFRC), in conjunction with the US Department of Energy (USDOE), has developed a rating system for window performance.
One of the most critical NFRC tests is for the window products U-Value, which measures a windows resistance of heat loss. The lower the U-Value, the better the window is at resisting heat flow, which results in a window with a greater insulating value.
Another critical NFRC test is for Solar Heat Gain Coefficient (SHGC). This procedure measures how well a window might block the heat caused by sunlight. Again, the lower the number, the less of the suns solar heat the window transmits into the home.
* Ratings vary by window style
Low-E Insulated
Glass Unit
with Argon Gas
Low-E Insulated
Glass Unit
with Argon Gas
Insulated
Glass Unit
no fill
Glazing
Most critical during heating seasons, the lower the U-Factor, the greater a window’s resistance to heat flow, and its insulating value. U-Factor ratings usually fall between .20 and 1.20, with a lower U-Factor indicating that your furnace won’t need to run as much, saving you money on heating costs.
Most often displayed as a number between 0 and 1, Visible Transmittance measures the amount of light that is transmitted through a window. More specifically, Visible Transmittance is the portion of the electromagnetic solar spectrum that produces light that can be seen by the human eye.
Most critical during cooling seasons, a lower Solar Heat Gain Coefficient (SHGC) means that less solar radiation is being admitted through your windows. Often indicated by a number between 0 and 1, a lower SHGC will mean that your air conditioner will not be required to operate as much.
