Replacement Windows Ratings | Understanding Replacement Window Ratings Systems

Window Replacement Rating Factors

The National Fenestration Rating Council was created with the consumer in mind. After all, how is a homeowner to know just how a window will perform; it's not as though you can take it home, try it out and bring it back if it doesn't work. Therefore, the Council does the legwork for you, offering comparisons between various models and manufacturers. From the features of each window to how they perform in terms of energy characteristics, the NFRC will offer specific information on the model and type of replacement window you are considering for your home to ensure that you are an informed, educated consumer when it comes to the purchase of a replacement window.

Some key rating information to consider when looking over NFRC information includes: the amount of air leakage, u-factor, any visible transmittance and solar heat gain coefficient.

Energy Star Window Program

The Energy Star program was created by the Environmental Protection Agency (EPA) in 1992. The goal of the program is to highlight those electronic products that promote energy efficiency. When it comes to windows specifically, Energy Star has a program specifically geared towards windows. The Energy Star Window Program is one that has given way for amazing advances in window technology. Through this program, some of the world's largest window manufacturers have worked with Energy Star to create windows that look good and perform even better. These windows are versatile and benefit the environment, all while costing you less than traditional windows.

The best replacement window ratings are those that are both Energy Star approved and those that pass NFRC ratings. However, most of all, the windows in question should be highly rated by the consumers, themselves, which is the ultimate litmus test of quality.

NFRC Ratings System

There are many window companies out there that will advertise replacement window products with a great U-value and make consumers believe these values are real. However, without the proper NFRC testing standards in place, these windows are only as good as the words of the salespeople. The same is true of the Energy Star approval system, which ensures that consumers will get the product they think they are getting in a replacement window.

Replacement Window Rating Factors and Choices

Options such as U factor, solar heat gain coefficient, condensation resistance, air leakage and visible transmittance may sound a bit foreign to you but they all relate to the efficiency level of your home replacement windows and by understanding what some of these terms mean, you will have an easier time choosing the right windows for your home.

U Factor – The U factor is the single most important rating for homeowners to consider when purchasing replacement windows, especially for those living in colder climates. U factor ratings measure the amount of heat loss that occurs through the window. This is such an important rating factor because heat loss is the main reason people seek to replace their old drafty windows in the first place. The U factor rating system was developed by the NFRC (National Fenestration Ratings Council) and most windows have U factor ratings between 0.2 and 1.3, with the numbers on the lower end of the scale being the best. For example, windows that have a U factor of 1.3 are usually old metal casement windows, while some of the most efficient thermal windows that have triple panes of low-e glass have U factors of 0.25. Most decent single pane windows have U factors in the 1.0 range, and if you add a storm window that rating falls to around 0.6. Double pane windows with low-e glass are even better than that, falling in the 0.4 range, but cannot compete with the extremely efficient triple pane windows.

Solar Heat Gain Coefficient – This is pretty much the opposite of the U factor. While the U factor measures how much heat loss occurs through the window, the solar heat gain coefficient measures the amount of heat gain that occurs throughout the warmer months. For those homeowners that live in warmer climates, this number is equally as important (or more) to the efficiency of their windows as the U factor. Ratings of solar heat gain coefficient range from between 0 and 1 with lower numbers being more efficient.

Condensation Resistance – This rating measures how well a window can resist the formation of condensation. For those homeowners that live in very humid climates, this is an important rating to consider, although condensation issues are becoming a bigger issue for many homeowners that have well insulated or poorly ventilated homes in an effort to be more energy efficient. These rating numbers are better, the higher they are.

Air Leakage – This is another important rating that determines how energy efficient your new windows will be because it measures how much outside air will be able to flow into your home through the windows. Ratings are usually between 0.1 and 0.3 and fixed and awning style windows usually top the list of the window styles with the least air leakage.

Visible Transmittance – This rating has less to do with efficiency than the previous ratings and more to do with personal preference. Visible transmittance (or VT) measures how much light can pass through the window. The higher the rating, the more light that will pass through your replacement windows and brighten up your home.

There are also a wide variety of new technologies that are on the market and allow for the production of many different types of windows with different features. Some windows have low-e glass that adds to the efficiency. Others have argon gas between the panes. Some windows require virtually no upkeep because of the materials used to construct the frames (such as vinyl).

Consumer Reports On Replacement Window Ratings

When it comes to windows, the consumers themselves are some of the best sources of reviews. These reports are usually based on sheer experience instead of just lab tests. Some of the best-rated windows include clad windows. These windows are best because they don't require maintenance of any sort for the outside of the window. Marvin and Andersen windows are also best, running between $250-400; however, many consumers rate Pella Inpervia among the best.

Replacement Window Rankings From Consumer Reports

Window - Manufacturer - Material

Clad Ultimate - Marvin Windows and Doors - Wood Window

Wood Ultrex Integrity - Marvin Windows and Doors - Wood Window

400 Series Tilt Wash - Andersen Windows - Wood Window

ProLine - Pella Corp. - Wood Window

200 Series Tilt Wash - Andersen Windows - Wood Window

Designer Series Precision Fit - Pella Corp. - Wood Window

500 Series - Peachtree Windows and Doors - Wood Window

Select Clad - Crestline Windows & Patio Doors - Wood Window

Weather Shield Custom Shield - Weather Shield Windows & Doors - Wood Window

Premium Wood Tradition Plus - Jeld-Wen Windows and Doors - Wood Window

5600 Series - Reliabilt/Survivor Windows - Vinyl Window

UltraMaxx Replacement - Alside - Vinyl Window

9500 Series - American Craftsman - Vinyl Window

Bryan Mawr II - CertainTeed Corp. - Vinyl Window

CrestFit Vinyl - Crestline - Vinyl Window

ThermaStar 25 Series - Pella Corp. - Vinyl Window

Impervia - Pella Corp. - Fiberglass Window