How much thought do you give to the glass in your windows? Probably not much, say the energy efficiency experts at Window and Siding Planet. Considering your windows account for up to 25% of annual energy expenses, it may be time to start thinking about the class of your glass.

Thermal performance rating

Window and Siding Planet representatives explain that the thermal performance rating of windows determine how much heat, condensation, and light are allowed to penetrate and escape a home’s interior.

U-Value (U)

U-Factor ratings are measured between .2 and 1.2. The lower the number, the more heat that is prevented from leaking outside.

Solar heat gain coefficient (S)

Working in conjunction with the U-Factor, the solar heat gain coefficient (SHGC) gauges how effectively the window guards against heat generated by the sun. SHGC is expressed between 0 and 1, with lower numbers representing better performance, according to Window and Siding Planet installation techs.

Visible Transmission (V)

Again measured from 0 to 1, the VT describes the amount of light that passes through the product and into your home.

Condensation Resistance (C)

The condensation resistance measurement illustrates the potential for window condensation. This is applied to either the glass itself or the glazing system.

energySMART Glass, which is available in select Polaris window products offered by Window and Siding Planet, boasts the industry’s best values on all thermal performance ratings. If you wish to reduce your carbon footprint, select double or triple pane windows insulated with low-E glass and argon.

Foam fill

Foam filled vinyl frames add to the efficiency of your home’s windows and further reduce air leakage. Window and Siding Planet proudly carries a full line of Polaris window products that feature ENVIRONMENTAL GREEN™ poly-foam fill.