ENERGY STAR vs. AERC vs. NFRC
Shopping for windows means meeting three sets of letters. Here is who is behind each one, what it tells you, and which to look at for a storm window.
Three labels, three jobs
ENERGY STAR
A government-backed label. It tells you a model meets the program’s requirements for a climate zone. It is a yes-or-no mark, so it is easy to read but does not rank one certified window against another.
AERC
The Attachments Energy Rating Council rates window attachments, which include storm windows. Its label gives performance numbers, such as U-factor, solar heat gain, visible transmittance and air leakage, so you can compare models.
NFRC
The National Fenestration Rating Council rates windows, doors and skylights. Its label is the one you see on new replacement windows, with similar numbers measured for the whole product.
Side by side
What it covers
- ENERGY STAR
- Many product types, including storm windows.
- AERC
- Window attachments, including storm windows.
- NFRC
- Windows, doors and skylights.
What it gives you
- ENERGY STAR
- A pass for a climate zone.
- AERC
- Performance numbers to compare.
- NFRC
- Performance numbers to compare.
Best used for
- ENERGY STAR
- A quick check that a model meets the bar.
- AERC
- Comparing storm windows and other attachments.
- NFRC
- Comparing replacement windows.
Which one to look at
If you are adding a storm window to a window you already own, look for ENERGY STAR for the bar and AERC for the numbers. Together they tell you that a model qualifies and how it performs.
If you are replacing the window itself, the NFRC label is the one to compare. It rates the window as a whole product.
Rebate programs often name one or more of these labels in their requirements, so check yours before you buy.
FAQs
Which label matters most for storm windows?
Start with ENERGY STAR to see whether a model meets the bar for your climate zone, then look at the AERC ratings to compare how models actually perform. NFRC labels are for windows, doors and skylights, so you will mostly meet them on replacement windows.
What is NFRC?
The National Fenestration Rating Council is an independent nonprofit that rates the energy performance of windows, doors and skylights. Its label is the familiar one on new replacement windows.
Can a window have more than one label?
Yes. A storm window can be ENERGY STAR certified and AERC rated. They answer different questions: one tells you the model meets a bar, the other tells you how it performs.
What is the difference between AERC and ENERGY STAR?
ENERGY STAR sets a bar that a model either meets or does not, for a climate zone. AERC does not pass or fail a product; it rates how the product performs, with numbers you can compare. A window can carry one label, both or neither.
What is AERC?
The Attachments Energy Rating Council (AERC) is an independent, nonprofit organization that rates the energy performance of window attachments, a group that includes storm windows. Its ratings are published in a public directory so products can be compared on the same terms.
What is the difference between the Northern and Southern ENERGY STAR zones?
ENERGY STAR certifies storm windows for climate zones. A model listed for the Northern zone has glass that lets in more solar heat, which suits colder climates. A model listed for the Southern zone has glass that blocks more solar heat, which suits warmer ones. Some models are listed for both. Choose a window listed for where you live.
Are storm windows eligible for tax credits or rebates?
The federal Energy Efficient Home Improvement Credit ended for property placed in service after December 31, 2025, so there is no current federal credit for windows. Some utilities, states and local programs still offer efficiency rebates, and many ask for ENERGY STAR certified or AERC-rated products. Programs and amounts vary, so check with yours before you buy. We cannot promise any specific rebate, but we can supply certification details for a model on request.
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