When shopping for new windows, you are sure to come across window performance ratings. These ratings can be a great way to compare different windows, but only if you fully understand them. So what do these window ratings mean, which ratings are important, and who comes up with these ratings?

Window Rating Terminology

• U-Factor: The U-factor or U-value measures the amount of heat loss of a window. The lower the U-value, the better the window performance.

• Solar Heat Gain Coefficient (SHGC): As the sun hits your window, it absorbs heat gain, which is measured in terms of SHGC. SHGC is expressed as a number between 0 and 1. The lower the SHGC, the better. A high SHGC means that a window allows heat to pass right through it, raising the temperature inside your home.

• Visible Transmittance (VT): VT measures the amount of visible light transmitted through a window. The higher the VT, the more light is transmitted.

• Air Leakage (AL): Heat loss and gain occur by infiltration through cracks in the window assembly, which is indicated by the AL rating. The lower the AL, the less air will pass through the window.

And who is responsible for coming up with the above ratings?

The National Fenestration Rating Council (NFRC), an organization formed by members of the window, door and skylight industry, uses input from suppliers, builders, architects, manufacturers, government agencies, and more to determine window ratings.

Architectural Window Supply: Your Source for Replacement Windows

Understanding replacement window ratings is just the beginning. To ensure that you choose the right window for your home, come to Architectural Window Supply! Our window experts will review your plans and discuss what you want to achieve, before they show you the many options available from our numerous suppliers. We offer a vast array of custom window options that give a stylish, sophisticated look to any residential home or commercial building.

If you have any further questions about Window Ratings, any of Architectural Window Supply’s other vendors, or if you wish to schedule a free consultation, please contact Architectural Window Supply by calling 410-266-5254 or visit our website!

Since 1995, Architectural Window Supply, Inc. has been the premier supplier of custom wood windows and doors in the Baltimore/Washington area. We offer a vast array of custom window and door options that give a stylish, sophisticated look to any residential home or commercial building.

We base our business on the principles of courtesy, quality and service as well as a solid knowledge of our products!

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Understanding Replacement Window Ratings Will Help You Get the Right Window For Your Climate