A step-by-step guide to energy efficiency ratings on windows in order to educate homeowners on how to choose the proper window for their home improvement project.

With an estimated 40% of American’s household budgets going toward heating or cooling, it is no surprise that high energy-efficient windows are at the top of the wish list for home improvement. The industry has set high standards and online tools that consumers have easy access to. This helps to define the technical jargon, and narrows down the massive amount of choices

There are three main steps to picking the perfect window:

1. Understanding window efficiency ratings and what they mean — how to properly read the labels and understand your needs
2. Shopping and comparing the different manufacturers, as well as the vendors who sell their products
3. Choosing an installation contractor

Picking That Perfect Window
Looks are important for sure, but so is the efficiency rating. Your windows may be pretty to look at, but if they let precious heating or cooling escape, it is not beneficial to you or your wallet when the bill comes along. To start off with, double-pane windows are three times as efficient as single-pane windows, so start with that and then budget if you can.

Ratings and what they mean:

• U-factor — Here, a lower number equals a higher efficiency rating. The numbers can range from 1.1 to 0.3. A low U-factor can indicate the overall quality of the window itself, and a poorly-made window cannot score a low U-factor number.
• R-factor — Opposite the U-factor, but working together with it, is the R-factor, in which a higher number means a higher efficiency rating. In addition, a higher number supports the lower U-factor. R-factor numbers usually range from 0.9 to 3.0.
• Low-E-factor — Again, a higher number indicates a higher efficiency rating. This number results from the microscopically thin coating on the windowpane itself, which is typically a metal oxide that reflects the heat back into the room.
  A “low-emissivity” number is the rate of heat reflection. This can be either a hard or a soft coating, with the former lasting much longer than the latter. The higher the e-factor a window has, the more protection you get from UV rays. These coatings also reduce energy loss anywhere from 30 to 50%, and are usually trademarked and unique to each manufacturer.
• Other Factors — The Solar Heat Gain Coefficient (SHGE) depends on the climate you live in. Colder climates need a higher rating, while the opposite is true for hotter climates. Inert gases are also found in multi-paned windows. They are sealed and filled with a gas such as krypton or argon, which make them more efficient than non-gas filled windows.

Windows can also receive multiple certifications, these being an Energy Star from the U.S. Department of Energy (DOE) and the U.S. Environmental Protection Agency (EPA), or from the National Fenestration Rating Council (NFRC), which identifies energy ratings. Check the label to see which certification your window has received.

Ready to Go?
First, prepare a preliminary budget. Then visit showrooms armed with the knowledge you have gained on energy and efficiency ratings; visit several showrooms if possible. When you are at the showrooms, ask for customer referrals and check them out. Also ask for a copy of the warranty for any vendor you are interested in, and compare to the other vendors to get the best deal. Finally, ask for contractor referrals.

Some window manufacturers offer training classes for contractors, for their specific product. These can be a good pool of candidates for your personal selection, as they will have proper training and will know what to do in case of problems.

Make sure to get a copy of the contract and a written proof of insurance, called a Certificate of Insurance. And never pay in full for the job upfront – arrange partial payments if necessary.

Any good and honest contractor knows and understands homeowner safeguards, and will likely offer the information up front; but in case they don’t, ask. Becoming an informed consumer will make your window installation a breeze, and keep you cool in the summer and warm in the winter for years to come.