What Are Energy Performance Ratings for Windows?

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If you have an interest in purchasing replacement windows for your home, it should be understood that one of the most critical factors you will need to consider is the energy performance rating of those windows. In short, this will inform you of how much heat and how much light may be successfully transmitted through a particular window. 

It also provides information on how much air may leak from a particular window. It is imperative that you consider the performance rating as it directly impacts the degree of energy efficiency that particular window has. Continue reading to learn more about energy performance ratings for windows. 

The Basics 

Window energy performance ratings measure the level of energy efficiency of a window. These are determined by an organization that does testing and certifications on windows, skylights, and even doors. It is the National Fenestration Rating Council or the “NFRC”, for short. Each Energy Star window contains a label from the NFRC. A window that has been certified as being “Energy Star” means that that the solar heat gain coefficient and the U-factor rank to offer energy efficiency.

What is a Solar Heat Gain Coefficient?

The solar heat gain coefficient or the “SHGC” for short is the amount of solar-based heat that reaches the window and it compares to the amount of heat that is able to get inside of the structure once the window is in place. 

What is the U-Factor?

The U-factor is the rate in which the loss of heat occurs with a window. The resistance to the heat flow indicates an insulated window. The higher level of resistance that a window has, it means the higher level of insulation. If there is a lot of insulation, the U-factor will be a low number. 

What is a Visible Transmittance?

The visible transmittance is a value that relays the amount of light that is able to get through the window. Today, there are many types of technologies – such as low-emissivity coatings – that allow a high level of light in a window without resulting in the allowance of heat within the structure. 

What is Air Leakage?

Air leakage is defined as the amount of air that leaks through the frame of a window. Materials that are used to create the frame have the potential to contract and expand, over time. The air leakage amount listed on a performance rating of a window is only an estimate and may actually vary over time. 

What Does This All Mean? 

The energy performance ratings for windows are considered to be of the highest level of performance because these are capable of helping a homeowner determine the amount that they will save on energy if they actually purchase the replacement windows and have them installed. To find these, look for the NFRC label on the window. 

In most instances, it is located on the lower right-hand region and includes – a minimum – of four ratings. If you are in the market for replacement windows, contact us here at Southern Industries Home Improvements today and we can assist in choosing the windows with the best energy performance ratings for windows for your individual needs. You may call us now at: (833) 240-4900



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