Independent Energy Ratings for Windows – What Does the NFRC Sticker Mean?

If you’ve ever done research on windows and their energy efficiency ratings, you’ve probably heard of or at least seen the white ratings sticker stuck to the glass. This sticker presents objective ratings from the National Fenestration Ratings Council or “NFRC.” The NFRC is an independent, non-profit organization that establishes objective window, door, and skylight energy performance ratings to help you compare products and make informed purchase decisions.

Given all of the information out in the digital world and the various data points offered by window salespeople, we thought it would be helpful to provide a brief overview of the ratings numbers, what they mean, and how you can use them most effectively.

​Learn more below!

What is the NFRC Sticker?
The NFRC sticker is a method of presenting four key ratings numbers for a window, based on how the window performs given its unique design features. On this sticker you will find four ratings. These rating are uniform across the window industry for manufacturers who participate in the NFRC rating program. Let’s dive in.

1. U-Factor
This number is a measurement of how much heat is being lost from the inside of your house to the outside. Thus, this number is intended to indicate how much heat a window allows to transfer to the outside. If you are concerned about keeping heat in your house, the lower this number is, the better the window will be at preventing heat loss.

In the U.S., a lower U-Factor will be more important to those living in the northern states, whereas the southern states will want a higher number to allow heat to escape.

The range of the U-Factor rating is from 0.10 to 2.00.

2. Solar Heat Gain Coefficient (“SHGC”)
This number represents the amount of heat gain from the sun that enters into your house. It’s like the opposite of the U-Factor as the heat is coming in instead of out, but the heat being transferred is coming directly from the sun’s rays. The lower the SHGC number is, the lower the amount of heat gain the window allows in from the sun. So, if you are concerned about a lot of heat gain from the sun, you should look for a lower number here. By contrast, if the sun’s warming rays are a welcome visitor to your house, a higher number can be beneficial.

In southern states that get a lot of sun, where keeping a cooler house is the priority, a low SHGC number is key. In northern states that experience warm temperatures during the summer months, and freezing cold temperatures in the winter months, a more balanced, medium rating is typically the goal. In these states, having solar heat gain in the winter months is helpful in warming the house and reducing heating bills.

The range of ratings for SHGC is from 0.00 to 1.00.

3. Visible Transmittance
The rating associated with visible transmittance measures the amount of natural light that enters your house, without heat. The higher the number for this rating, the more natural light will enter your house through the window. A higher number in this rating is normally desirable across the board to homeowners, given that this helps reduce the need for artificial light, and therefore, can reduce electric bills.

The range of ratings for visible transmittance is from 0.00 to 1.00.

4. Air Leakage
This rating deals with the amount of air that is able to pass through a window. Obviously, the less air that is leaking through a window, the better it will perform from an efficiency perspective. Ratings equal to or less than 0.3 will mean better performance and less drafts.

The range of ratings for air leakage is 0.00 up to 0.30.

How to Use the Ratings

Now that you are familiar with the NFRC ratings on each window sticker, how can you use these numbers to inform yourself and your decisions?

Although NFRC ratings are just numbers, they can be very useful when considering various alternatives. In fact, these ratings are a great way to compare “apples-to-apples” when trying to find the best choice for you and cut through the clutter. In the modern world of windows, there are a multitude of different styles, colors, features, and materials available to choose from.

While some of these options are more personal and can lend themselves to design choices, the NFRC ratings help you ensure that the windows you choose not only look great, but perform well too. Finally, these ratings can help cut through the sales pitch and create an objective, level playing field in terms of comparing competing alternatives. A reputable, well established window company should be able to help navigate all the options and ratings and guide you along the path to your best decision.

At Best Door & Window, we pride ourselves on helping provide information and transparency to folks every day. If you have questions about windows, contact us today. We are here to help!