Choosing the Best Replacement Window

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How To Choose the Best Replacement Window

Understanding the NFRC Window Quality Rating

Just like you can’t judge a book by its cover, it’s often difficult to judge the quality of a new window just by looking at it. Until the late 1980s, not having the tools to choose the best replacement window was a problems for homeowners, builders and government agencies alike. Everything might look good in the store or catalog but once you got it home and installed, the performance problems became apparent.

But around that time, the National Fenestration Ratings Council (NFRC) was formed to address these issues. Once this happened, people were finally able to make apples-to-apples comparison of several windows brands based on reported, standardized data.

The standards developed are also the benchmark quality rating for other kinds of quality assurance programs. For example, in order to apply for the popular ENERGY STAR ® label, a requirement of many government energy rebate programs, window manufacturers must first test their products according to NFRC procedures, including independent testing at NFRC approved laboratories.

What Does This Label Mean to You?

NFRC Logo SampleThe NFRC is an independent, non-profit organization formed to serve the public through education, testing and research. For consumers, the most important function of this organization was the creation of a label system that establishes common standards across all windows so consumers can choose the best replacement window for their home. The NFRC label on a window product shows the results of the independent ratings from NFRC-certified laboratories. Without this label, the product is not certified to meet basic industry standards for quality.

Here are key terms you’ll see on an NFRC label:

Certified Products Database (CPD) Number – The number provides consumers access to a database with information about the manufacturers, products, and performance ratings of the window. You can access this database at

U Factor – Measures the heat from inside the room that can escape through the window. U-factor ratings generally fall between 0.20 and 1.20. The lower the number, the better the product is at keeping heat in.

Visible Transmittance (VT) – Measures how much natural light can come into a room. This is expressed in numbers between 0 and 1. The higher the number means the more natural light you’ll receive through the window, sometimes known as daylighting.

Solar Heat Gain Coefficient (SHGC) – Measures the amount of outdoor heat that can enter a room. This factor is expressed in numbers between 0 and 1. The lower this number, the better the product will be at blocking unwanted heat gain, particularly important during the summer cooling season.

Air Leakage (AL) – By far the most important factor, this measure represents how much air will enter a room through the product measured in how many cubic feet of air can pass through the window per minute in a constant 25 mph wind divided by the total window area. The NFRC only certifies products that measure AL at 0.3 or less. All the window products we carry at Home Town Restyling carry a rating of .01 or less. You should note that since this is an optional measure, many window sellers choose not to include it on their labels. If you see a window label without an AL, you should ask the dealer for any information available about this important rating.

Independent, Fair and Credible Window Ratings

The success of the NFRC label system comes from the agency’s non-profit independent status. Window dealers and manufacturers have no input into how the various products are rated.  That’s why many local, state and federal energy saving codes encourage the use of only NFRC rated window products.

Home Town Restyling carries a complete line of NFRC rated windows along with licensed and insured crews for professional installation. If you are thinking about replacing some or all of your home’s windows, stop by or contact us for a free estimate. You can also download our FREE Window Replacement Checklist to learn what else you need to know and start planning for your new windows like a pro.

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