Window Ratings

When purchasing replacement windows, you want the best performance and value possible. How do you know that you’re getting the quality product you deserve? One way to protect your home is to learn some basics about window ratings.

Why are window ratings important?

Window ratings are provided by the National Fenestration Council (NFRC) as a measure of the window’s over-all energy efficiency, durability, light transmittance, and more. These measurements offer unbiased information that can help you make the best choice for your home—and avoid some misleading sales tactics in the process.

What is a Quality R-Value or U-Factor Rating?

Energy efficiency is an important factor to consider when purchasing new windows. Both the R-Value and U-Factor indicate the thermal performance of the window; However, they do not offer the same information.

R-Value measures the center of the window glass only. U-Factor is comprehensive. This measurement considers the entire glass as well as the window frame.

Sales trap: A sales rep might boast of a high R-Value rating, but the over-all quality of the window leaves plenty to be desired. When given a choice, look for the U-Factor.

Quality rating: A quality U-Factor rating is between 0.17 and 0.39. A lower number means better performance. A quality R-Value is between 2.5 and 6. A higher number means better performance.

What is a Quality VT Rating?

A common reason for new windows is natural lighting. This feature is known as visible transmittance, hence the term VT Rating. This rating lets you know how much light can come into your home through the window.

Just keep in mind that this rating is not affected by the window glass alone. Window grids, glass coatings, and frame thickness block light and can reduce the rating significantly.

Sales trap: A sales rep might boast of how much brighter your space will be if your purchase their brand over another. As mentioned above, the only way to get an accurate comparison is to look at the VT Rating of windows with like features.

Quality rating: The higher the score the more light you are getting from your window. VT Ratings range between 0 and 1, with the typical rating falling between 0.30 and 0.80.

What is a Quality DP Rating?

Design Pressure (DP) Rating is used to measure the strength of the window frame against wind and static snow, which is important to consider if you want replacement windows that will last in tough weather conditions.

Sales trap: A window salesperson might point to a thick window frame and claim that their window is stronger than another with a thinner frame. This is not always the case. Frame durability is not related to frame thickness, but rather the quality of the frame material and manufacturing process.

Quality rating: Homes and commercial buildings that are in storm-prone areas, such as hurricane zones, should invest in windows with the highest DP Rating possible. In general, 15 to 50 is considered a quality range.

Are There Other Ratings to Consider?

Thermal transmittance, visible light transmittance, and durability are important factors to consider when purchasing replacement windows, but there are additional ratings that you might want to look at:

·  STC Rating measures sound transmittance. If you want a window with good sound-proofing ability, look for a range between 28 and 48. A range of 18-20 is standard.

·  CR Rating measures condensation resistance, which is a desirable trait for energy efficient windows. Ratings between 30 and 80 are considered ideal.

·  Air Infiltration determines how much air can pass through a window during a constant, 25 mph wind. If this is a concern for you, look for a rating of 0.30 cfm/sqft or lower.

Do you want replacement windows with good ratings?

At New Windows for America, we are proud be a preferred choice for replacement windows, and we don’t have to resort to tricky sales tactics to attract customers. We offer highly rated windows, professional window installation, and courteous service from skillful window contractors.

To learn more about window ratings or to get a free window installation cost estimate, contact New Windows for America today!