To qualify as Energy Star windows, products must meet several rating requirements that measure product performance. Oftentimes, manufacturers use different materials or coatings to boost a window's insulation or radiation reflection. These special materials can help windows qualify as Energy Star windows. Read on for more information on the ratings for Energy Star windows
The Ratings for Energy Star Windows
In order to qualify as Energy Star windows, there are several requirements that your windows must be able to meet. First, they must be manufactured by an Energy Star windows partner. Next, your windows must be tested and certified by the National Fenestration Rating Council (NFRC). Finally, your windows' ratings must meet the U.S. Department of Energy's Energy Star windows guidelines.
The NFRC rates all windows' performances in five different categories:
1. A window's U-factor, generally ranging from 0.25 to 1.25, measures the rate of heat transfer and how well insulated the window is.
2. Its solar heat gain coefficient (SHGC) measures the total solar energy transmitted and how well the window is able to block the heat caused by sunlight. A window's SHGC usually falls between 0.25 and 0.80 on a scale of 0 to 1.
3. Condensation resistance measures how well a window resists the build-up of moisture. This is rated on a scale from 0 to 100. The higher the condensation resistance factor, the less build-up the window allows. In wet or humid regions, homeowners may want to weigh condensation resistance more heavily.
4. Air Leakage (AL) measures the amount of air that passes through a window's joints. According to the Energy Star website, AL "is measured in cubic feet of air passing through one square foot of window area per minute. The lower the AL value, the less air leakage."
5. Visual Transmittance (VT) measure the amount of light that the window lets through. VT uses a scale of 0 to 1, and a window usually scores between 0.20 and 0.80. The higher the VT, the more light passes through your window.
For more information on these ratings, check out Energy Star's website on Energy Star windows.
How to Make Your Windows Energy Star Windows
There are several components to energy star windows that add to their energy efficiency. Low-glass is an improved window coating capable of improving insulation in the winter and reducing solar heat gain in the summer. When it comes to window frames, durable and well-insulated materials such as fiberglass or vinyl can also help your windows qualify as Energy Star windows.
Additionally, homeowners should consider double or triple-paned glass rather than single-paned glass windows, as this can significantly boost insulation. You may want to choose gas-filled windows with gas between the glass panes, which prevent even more heat loss to keep your home warm.
The Value of Investing in Energy Star Windows
Investing in Energy Star windows reduces energy bills and carbon footprints by 12 percent nationwide. If you choose to replace your single-pane windows with energy star windows, you may save $101 to $538 each month. Replacing double-pane windows may save you $27 to $153. Additionally, for energy star windows installed between 2012–2014, homeowners can claim a tax credit of up to $200 for 10% of their original window cost.