A Practical Guide for Buying the Right Vinyl Windows
December 14, 2009
If you're considering a vinyl installation project, one of your primary goals should be to buy the most energy efficient model available. As green initiatives begin to encourage consumers to become eco-friendly, vinyl window ratings are an effective way to determine if your purchase meets the standard.
Vinyl Window Ratings Demystified
At first glance, the bevy of terms within the rating system may be confusing and ultimately discouraging. Here's a list of definitions from the U.S. Department of Energy that explain the vinyl window ratings system and how it can potentially benefit your home.
- Heat Gain/Loss. In other words, how your windows gain or lose heat that may be costing you money on your monthly energy bill. Ratings terms to look for include U-factor--the conduction of non-solar heat flow, the solar heat gain coefficient (SHGC)--solar radiation admitted through a window, and air leakage--the rate of air infiltration.
- Sunlight Transmittance. This factor determines the amount of sunlight that can pass through your vinyl window. Rating terms include visible transmittance (VT)--a fraction of the visible spectrum of sunlight--and light-to-solar gain (LSG)--the ratio between the SHGC and VT.
- Energy Performance Program. Operated by the National Fenestration Rating Council (NFRC), this voluntary program that tests, certifies, and labels windows based on energy performance ratings.
A Final Word on Vinyl Window Installation
One way you can ensure that your vinyl window purchase adheres to the standards of the vinyl window rating system is to look for the ENERGY STAR label. This certification is the National Fenestration Rating Council's seal of approval for U-factor and SHGC ratings.