Tom Shafer

Why it matters if your windows are Energy Star compliant

April 15, 2015

My daughter bought a new home last week from a large national builder. We live in North Carolina, and Energy Star classifies our state as being in the South Central zone. (Their recommendations for windows will vary by region, so it's important to check where your home is located on their map before buying new windows.) The builders who constructed my daughter's home advertise an entire energy savings package included in the purchase price, and that includes Energy Star windows. And they were Energy Star windows in 2014 - but they aren't anymore. On January 1st, 2015, new Energy Star standards took effect, and what met their qualifications for the past year no longer cut it. Take a look at this label on a window to get a better ideas of the specifics:

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window label meaning

The National Fenestration Rating Council (NFRC) labels each window. They're a non-profit organization that empowers consumers who are in the market to see for themselves what qualifies as an energy efficient window. The NFRC label is the assurance that the windows perform to the labeled specifications. There are a couple numbers to look for on this label: u-value, which measures the heat inside the room that can escape to the outside, and solar heat gain coefficient (SHGC), which is the amount of heat outside that can enter the room. Lower is better for these numbers.

Here you can see the u-value is .35 and the SHGC is .30 for this window. This is what is in my daughter's new home. Now see below for the 2015 Energy Star Criteria, broken down by zone (North, North Central, South Central, and South).

Energy Star ratings

In order for the windows in my daughter's new home to qualify, they need to have a U-value of .30 and an SHGC of .25 or less.

A good way make a window more energy efficient so it meets the new standards is to replace the glass. The .25 SHGC criteria usually means that the glass needs to be a low-e 2, meaning a low-e with two reflective coatings. A low-e 3 glass - three coatings - along with an argon gas infill between the panes would make for a very energy efficient window.

Getting an extra coat in the glass would probably $30 -$50 per window (and it can go higher than that; it depends on labor costs in your area). On a house with 18 windows, that could be about a $900 upgrade.

The importance of meeting Energy Star standards is growing. Many local building codes require Energy Star compliance. Leading institutions also are starting to require that homes meet Energy Star standards to qualify for home loans. Utility companies in many areas will offer rebates or discounts for whole house Energy Star compliance.

So long story short: If you are buying a new home now, or getting replacement windows, make sure they comply with Energy Star 6.0. You'll be doing your wallet and the environment a big favor in the long-run.

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