Energy-efficient windows for Texas homes

What makes a window energy efficient in Texas?

Three numbers decide it: U-factor, solar heat gain coefficient (SHGC) and visible transmittance (VT). In North Texas, SHGC comes first, because summer sun does most of the damage. The U.S. Department of Energy says efficiency is “primarily a function of the U-factor (thermal transmittance) and solar heat gain coefficient (SHGC).”

DOE also says energy savings differ by climate. A window that works well in Minnesota can underperform in Dallas. Choose for your sun, your frame and your code. Then confirm the numbers on the label, not on a brochure.

What do U-factor, SHGC and visible transmittance mean?

U-factor measures heat flow through the window. SHGC measures how much of the sun’s heat gets in. Visible transmittance measures how much daylight gets in. Lower is better for the first two. Higher means brighter rooms for the third.

Rating	What it measures	Direction for Texas	Plain note
U-factor	Heat flow through the whole window	Lower is better	DOE: “the lower a U-factor, the less heat will flow through the window”
SHGC	Share of solar heat that gets in, 0 to 1	Lower is better	DOE: low gain products (under 0.4) are made for hot climates
Visible transmittance	Share of daylight that gets in, 0 to 1	Higher is brighter	DOE: values below 0.5 “noticeably reduce the amount of light”

The trade-off is real. DOE warns that tinting can reduce solar heat gain, but it “also reduces the ability to see clearly through a glazing unit.” Ask for a low SHGC and a VT that still feels bright. Read the full explanation in SHGC and U-factor for Texas.

How hot is Dallas-Fort Worth, and why does it change the glass?

DFW summers are long and hot, so cooling load drives the choice. The National Weather Service reports that at DFW Airport the average date of the first 100°F day is July 1 and the average date of the last is August 27. The most 100°F days in a year was 71, in 2011.

Degree days show the same pattern. A degree day measures how much heating or cooling a place needs. The NWS 1991 to 2020 normals list 2,825 cooling degree days a year at DFW, against 2,218 heating degree days. July and August each log more than 640 cooling degree days. Those are the months your windows work hardest.

That is why a Texas spec reads differently from a northern one. You want to block summer sun on east and west faces, and you still want daylight. Values for Love Field, Fort Worth Meacham and other stations are not covered here, because the NWS pages cited use DFW Airport.

What does Low-E glass do, and what about argon and spacers?

Low-E glass carries a thin coating that reflects heat. Argon fill slows heat flow between the panes. A warm-edge spacer keeps the glass edge warmer. Together they improve a window’s ratings, and they are standard on most good insulated units.

DOE says “windows with low-e coatings, especially spectrally selective coatings, are effective at reducing summer heat gain and air conditioning costs without significantly impacting visible light or color.” Read more about Low-E coating, argon gas fill and warm-edge spacers.

The partner makers describe their glass this way:

• Sun Windows. All Sun products use dual-glazed insulated glass as standard. Sun says argon “improves thermal performance by slowing convection currents” and that its Duralite spacer gives “a warmer edge-of-glass temperature.” Its Sun Advantage 270 Low-E² glass, per Sun, blocks 63% of the sun’s heat in summer, and the 366 is a third-generation Low-E³ glass with a triple layer of silver.
• Jada. Jada says argon improves performance in a 1/2 inch air space. Its NFRC samples use a Technoform TGI spacer and argon fill. See the table below.
• Bertrand. Bertrand publishes U-values for several systems and says it takes part in the NFRC program.

Metal frames need a thermal break too. ENERGY STAR notes that aluminum frame design “typically includes thermal breaks to reduce conductive heat loss through the metal.” Read thermally broken steel windows for the steel version of that story.

Which ENERGY STAR climate zone is Dallas in?

ENERGY STAR places Dallas County and Tarrant County, which includes Fort Worth and Southlake, in its Southern zone. Collin and Denton counties, which cover Plano and Frisco, fall in the South-Central zone. Confirm your address in the official finder before you buy.

ENERGY STAR says it is “important to select windows, doors, or skylights that are suited to the type of climate you live in.” Its limits vary by zone. The current ENERGY STAR page shows those limits as pictures, so this page does not print the numbers. Read the limits for your zone on the ENERGY STAR site, and see ENERGY STAR climate zone in the glossary.

The county list comes from the climate zone spreadsheet that ENERGY STAR links from its finder, read in November 2026. Zones can change when ENERGY STAR updates its rules, so recheck before you order. Frisco spans two counties, so a Frisco address needs a finder check.

How do I read an NFRC label?

An NFRC label reports the whole window’s tested ratings. DOE says all qualifying ENERGY STAR units “must be certified and labeled by NFRC,” and that labels “typically report VT.” Compare labels for the exact size, glass and grid pattern you plan to buy.

Jada gives a useful warning on this point. It tells buyers to confirm that quoted values are “for the unit value and not the center of glass values.” Center-of-glass numbers look better because they leave out the frame. Always ask which one you are reading.

Our guide on how to read an NFRC label walks through each line. The glossary entry for the NFRC label is a short version.

What do Jada, Sun and Bertrand publish?

Each maker publishes something different. Jada lists NFRC sample ratings. Sun describes its glass and spacers but lists no U-factors on the pages we read. Bertrand lists U-values in its own units. Compare only like with like, and ask for NFRC data on your exact product.

Maker	Published item	Value as published	Note
Jada	NFRC sample, outswing window, column Clr-NG	U-factor 0.37, SHGC 0.28	Sample glass: 1/4 inch over 1/4 inch unit, Technoform TGI spacer, argon fill
Jada	NFRC sample, outswing window, column IS20-SDL	U-factor 0.35, SHGC 0.25	Same sample build; grid and glass change the result
Jada	NFRC sample, direct-set fixed, column IS20-NG	U-factor 0.26, SHGC 0.32	A fixed unit, shown for comparison
Sun	Sun Advantage 270 Low-E² and 366 Low-E³	No U-factor or SHGC on the pages read	Sun describes the coatings and visible light share in words
Bertrand	Synergic, triple and double glazing	U factor 0,16 and 0,26, “confirmed by NFRC”	Bertrand’s own wording and comma style
Bertrand	Linear	U-value 0.73 W/(m²K)	A metric value, not the U.S. U-factor on a label

Jada’s page also says “swing products tend to rate better than sliding or folding products,” and that true divided lites rate lower than simulated ones. Both points help when you pick a window style. Read the Jada partner page, the Sun Windows partner page and the Bertrand partner page for the rest of each maker’s data.

Honey Rock does not publish its own performance claims. Ask for the NFRC record for the product you choose.

What energy code applies where I build?

It depends on the city. Texas set a statewide residential energy standard, but cities can adopt newer codes. As of November 2026, the cities below publish different editions. Confirm with your city building office, because codes and local amendments change.

Place	Energy code the city publishes	Source type
Texas (statewide)	2015 IRC, Chapter 11, effective Sept. 1, 2016	Texas Comptroller, SECO
Dallas	2021 International Energy Conservation Code with Dallas amendments	City of Dallas
Southlake	2021 International Energy Conservation Code	City guideline PDF
Highland Park	2024 IECC, as amended	Town builders packet
Frisco	2024 IECC with amendments, effective 06-02-2026	City adopted codes page
Fort Worth	2015 Energy Conservation Codes	City building and energy codes page

The U.S. DOE lists the current state code for Texas as the 2015 IECC. The Texas Comptroller’s State Energy Conservation Office reviews residential codes on a six-year cycle. The metro does not share one code. Frisco lists 2024 while Fort Worth lists 2015, so always say which city.

Read more in our post on DFW energy codes and new windows and the Dallas page, Southlake page and Fort Worth page.

Plano, McKinney and other cities are not in the table. Check with that city’s building office for its edition.

What does Highland Park ask for on its plan checklist?

Highland Park’s residential builders packet asks for window and door sizes with SHGC and U-factor, and lists “(SHGC < 0.25 max & U-Factor < 0.35 max).” It also asks for 2024 IECC compliance signed by an energy consultant with ICC certification. As of November 2026, that is what the packet says.

This is a plan-submittal checklist for residential permits. Whether it applies to a single window swap is not clear from the packet, so ask the Town. Read our post on Highland Park window and door permits and the Park Cities page.

A checklist limit of “less than 0.25” is strict. Jada’s lowest published SHGC sample for a window is 0.25, which does not sit under that line. That does not rule Jada out. It shows why you should get the NFRC value for the exact glass package before you submit plans.

Is there still a federal tax credit for windows?

No. The IRS says: “You can claim the credit for improvements made through December 31, 2025.” That date has passed, so the federal energy efficient home improvement credit no longer applies to new window work. Do not plan a budget around it.

Read our short post on the federal window tax credit that ended. Utility or city programs may exist, and their terms change. Ask your utility directly. This page is not tax or legal advice.

What should I ask before I order energy-efficient windows?

Ask for numbers you can check and a spec that fits each face of the house. Request the NFRC label values, the glass makeup, the spacer and fill, and the code your city enforces. Put the answers in writing.

1. What are the NFRC U-factor, SHGC and VT for this exact unit, with sash and frame?
2. Does the number include the grid pattern I chose?
3. What glass will I get on the west and east faces, and why?
4. Is the frame thermally broken? What spacer and fill does the unit use?
5. Which energy code does my city enforce, and does my permit need a compliance report?
6. Does the unit need ENERGY STAR certification for my zone, and does the maker list it?
7. What does the maker warrant for glass seals and finish?

Our glass options guide and planning a window and door project help you prepare. For historic homes, check approvals first in windows in Dallas historic districts.

Next step

Tell Honey Rock which faces of your house get the most sun and which makers interest you. Start at the windows overview and the energy-efficient windows page, then start your project or call (214) 484-9982.