ENERGY STAR windows are windows whose tested ratings meet efficiency guidelines set by the U.S. Environmental Protection Agency. The label depends on the climate zone, so a window certified for one region may not be certified for another. Everything here comes from ENERGY STAR's own pages, checked on October 13, 2026.
What Are ENERGY STAR Windows?
They are windows that meet three conditions, as of October 13, 2026: an ENERGY STAR partner makes them, the National Fenestration Rating Council certifies them, and their ratings meet EPA's efficiency guidelines.
The National Fenestration Rating Council, or NFRC, is an independent body that rates windows. ENERGY STAR lists the three conditions on its What makes it ENERGY STAR page. The same page says the program doesn't require any specific technology. Windows, doors and skylights first qualified for the label in March 1998, according to the ENERGY STAR windows page.
Which Ratings Does the Label Depend On?
Two: the U-factor and the solar heat gain coefficient, or SHGC. The required levels change with the climate zone.
ENERGY STAR's guide to replacing windows explains both:
| Rating | What it measures | Lower number means | Typical range for windows |
|---|---|---|---|
| U-factor | Insulating power | The window insulates better | 0.10 to 0.60 |
| SHGC | Solar heat that gets through | More of the sun's heat is blocked | 0.15 to 0.60 |
The current performance levels took effect on October 23, 2023, the ENERGY STAR windows page says. Each certified window carries a label showing where it is certified.
Which Ratings Suit a Hot Climate or a Cold One?
A low SHGC suits hot, sunny climates because it blocks solar heat. A low U-factor suits cold climates because it keeps heat inside.
The windows guide, linked above, gives two reference points:
- Northern United States: ENERGY STAR recommends a U-factor of 0.22 or less.
- The South: look for an SHGC of 0.23 or less.
The right levels depend on the climate zone where the home is. ENERGY STAR publishes its levels by climate zone, and the label on each window shows the zones it is certified for.
How Much Do ENERGY STAR Windows Save?
ENERGY STAR says certified windows lower household energy bills by an average of up to 13 percent nationwide when they replace single-pane windows.
That figure is on the ENERGY STAR windows page. The windows guide gives a second figure, an average of 12%, without stating what the old windows were. Both are national averages, not estimates for a California home.
The guide also says new windows may not pay for themselves through energy savings alone.
How Much Do ENERGY STAR Windows Cost?
ENERGY STAR gives one range: about $400 to about $1,600 or more per installed window, for a 3 ft. by 5 ft. double-hung window.
The range is in ENERGY STAR's guide to replacing windows. The low end is a simple, energy-efficient window with a good installation. The high end covers premium options such as specialty wood finishes or laminated glass.
Three more points from the same guide:
- An expensive window isn't always an energy-efficient one.
- Buying at least 10 windows at once helps lower the price per window.
- High-performance windows are made to order, and delivery typically takes 6 to 8 weeks, sometimes 12.
DuloCore has no verified price data for windows in California, so this page gives no local price.
Are There Rebates for ENERGY STAR Windows in California?
It depends on the utility. Window rebates in California are set by each utility, so the answer changes from one address to the next.
The guide to California window rebate programs lists what four utilities offered when DuloCore last checked their pages. The rebate calculator and the eligibility check show the verified programs for a specific address.
Frequently Asked Questions
What should I ask a window salesperson for?
The U-factor and SHGC of each window being quoted. ENERGY STAR says the salesperson should supply both and record them in the sales agreement.
Does the frame material decide whether a window is certified?
No. ENERGY STAR says certified windows come in a variety of framing materials.
Did the federal tax credit for windows end?
Yes. The federal 25C credit ended for windows installed after December 31, 2025.
The guide to the federal home energy credits that ended has the details.
Replacing windows? See the verified rebates for your address with the free rebate calculator.