--- title: "How to Read an NFRC Window Label: Ratings Explained" description: "Learn what each number on an NFRC window label means: U-factor, SHGC, visible transmittance and air leakage, and how to compare labels for a Texas home." url: https://honeyrock.multisites.ai/guides/how-to-read-an-nfrc-label publisher: Honey Rock Window and Door phone: +1-214-484-9982 quote: https://honeyrock.multisites.ai/contact-us --- # How to read an NFRC label on a window or door An NFRC label lists independent, third-party energy ratings for one window or door: U-factor (heat loss), solar heat gain coefficient (heat from the sun), visible transmittance (daylight) and air leakage. Lower U-factor and SHGC mean less heat moves through. Compare labels for the exact size, glass and frame you plan to buy. Updated November 5, 20267 min read ![A modern home with large windows lit warm at dusk](https://honeyrock.multisites.ai/_astro/dusk-modern-home-glazing-01.BqSa_uSH_ZVAdNj.avif) ## Four ratings The label can show U-factor, SHGC, visible transmittance and air leakage. Each one answers a different question. ## Lower is not always better Low U-factor and low SHGC help in Texas heat. Visible transmittance works the other way: a higher number lets in more daylight. ## Ratings are for one product A label rates a specific window or door with a specific glass package. Change the glass and the numbers change. ## Third-party check NFRC runs a certification system with computer models and physical tests. A maker cannot just print its own numbers. ## What does an NFRC label tell me? An NFRC label tells you how one window, door or skylight performs for energy. It lists ratings that an independent group certified. You can compare two products from two makers on the same scale. That is the whole point of the label. NFRC stands for the National Fenestration Rating Council. “Fenestration” is the trade word for windows, doors and skylights. NFRC says its label “helps you compare between energy-efficient windows, doors, and skylights by providing you with energy performance ratings in multiple categories.” The label does not rate looks, sound, strength or storm resistance. It rates energy. Read it as one input in your decision, next to the frame, the glass and the way the unit opens. See the [NFRC label](https://honeyrock.multisites.ai/glossary/nfrc-label) entry for a short definition. ## What do the numbers on the label mean? Each number answers one question. U-factor asks how fast heat leaks through. SHGC asks how much sun heat gets in. Visible transmittance asks how much daylight gets in. Air leakage asks how much air sneaks through the product. Rating Plain question Better direction Range NFRC shows [U-factor](https://honeyrock.multisites.ai/glossary/u-factor) How fast does heat leak through? Lower 0.20 to 1.20 [SHGC](https://honeyrock.multisites.ai/glossary/shgc) How much sun heat comes in? Lower in hot climates 0 to 1 [Visible transmittance](https://honeyrock.multisites.ai/glossary/visible-transmittance) How much daylight comes in? Higher 0 to 1 Air leakage How much air leaks in? Lower 0.3 or less NFRC puts it in its own words. U-factor “measures how well a product keeps heat from escaping a room.” For solar heat gain, “low numbers resist solar heat, high numbers allow solar heat.” Air leakage “measures how much air will enter a room through a product.” ## Why do hot and cold climates read the label differently? In a hot climate, you want a low SHGC to block sun heat. In a cold climate, you want a high SHGC to use free sun warmth. The U.S. Department of Energy says low gain products, under 0.4, suit hot zones. High gain products, over 0.55, suit cold zones. This is why one number cannot tell you “good” or “bad.” The same window can be right in Minnesota and wrong in Dallas. The Department of Energy tells buyers to “first identify the climate zone where they will be installed” and then pick products at or below the limits for that zone. North Texas has long, hot summers. For most Dallas and Fort Worth homes, SHGC and U-factor both matter, and SHGC is the one that often gets missed. The [SHGC and U-factor guide for Texas](https://honeyrock.multisites.ai/guides/shgc-and-u-factor-for-texas) goes deeper on targets and local code. ## What does visible transmittance mean for a glass wall? Visible transmittance, or VT, tells you how much daylight passes through. Higher means brighter rooms. Very low numbers make a room feel dim, even in a house with big openings. The Department of Energy warns that “VT values below 0.5 noticeably reduce the amount of light transmitted.” It also advises: “When purchasing windows with a low SHGC, verify that the VT is not too low.” This matters for the homes Honey Rock’s customers plan. Large steel or slim-frame openings exist to bring in views and light. A deep tint can cut heat, but it also cuts light and changes the view. Ask for the SHGC and the VT together, and compare two glass options side by side. ![Afternoon light through a wall of glass](https://honeyrock.multisites.ai/_astro/light-living-glass-wood-ceiling-01.DVsux7tl_ZNR1iR.avif) ## How does NFRC make sure the numbers are real? NFRC uses computer models and physical tests. Its residential program “uses a combination of simulations (computer modeling) to determine energy performance (U-factor, SHGC, VT) for product lines, and physical testing (NFRC 102) to validate those simulations.” That means a maker cannot invent a number. A lab must test or model the product. Jada describes the same path on its energy page: “each product is computer modeled and then physically tested to verify the model.” The result is “a certified core product rating that can be altered depending on the glass type that is used.” Bertrand states that it “is part of the NFRC Product Certification Program.” For any brand, still ask for the rating of your exact product. A program badge does not replace the rating for your window. ## Is an NFRC label the same as ENERGY STAR? No. The two are linked but not the same. NFRC is “the official certification body for ENERGY STAR® windows, doors, and skylights.” A product earns ENERGY STAR status when its NFRC ratings meet the limits for a climate zone. So an NFRC label gives you the ratings. ENERGY STAR gives you a pass or fail for a zone. ENERGY STAR says its window criteria “vary for each of the climate zones.” The criteria are in tables on the ENERGY STAR site. This guide does not print Texas limits. Check the current ENERGY STAR page and your city’s energy code for the target that applies to your address. Learn how climate zones work in the [ENERGY STAR climate zone](https://honeyrock.multisites.ai/glossary/energy-star-climate-zone) entry. ![Rain on a window at night](https://honeyrock.multisites.ai/_astro/detail-rain-on-glass-bokeh-01.C5vQdMwl_PPC5n.avif) ## Why do two windows from one maker show different numbers? The glass, the grid style, the size and the product type all change the rating. A maker rates each combination. Jada’s energy page shows this clearly with sample ratings for one glass package. Jada sample product U-factor SHGC Direct-set fixed, Clr-NG column 0.31 0.32 Outswing window, Clr-NG column 0.37 0.28 Outswing door, Clr-NG column 0.33 0.31 Folding door, Clr-NG column 0.34 0.32 Sliding door, Clr-NG column 0.37 0.32 Jada calls this “a sampling” of its NFRC numbers. Its sample glass is a 1/4 inch over 1/4 inch insulated unit with a Technoform TGI spacer and argon fill. The page lists more columns for a second glass type (IS20) and for simulated divided lites (SDL). It also says “Swing products tend to rate better than sliding or folding products.” Grids matter too. Jada explains that simulated divided lites “rate better because the divided lite elements do not break up the glass.” True divided lites look the same from the street, but they rate lower. If you want true divided lites, ask for the rating with that grid. ## What should I ask a supplier to show me? Ask for the whole-window NFRC rating for each product type on your plans. Ask for it with your grid style, your glass package and your size. Then compare those figures with your target. Jada gives a useful checklist on its energy page. Two items stand out. First, “confirm that the energy performance values quoted are for the unit value and not the center of glass values.” Center-of-glass numbers look better than whole-window numbers because they leave out the frame. Second, confirm the glass package used in the published values is available and not cost prohibitive. Use this short list: 1. List every opening type on your window schedule: fixed, casement, door, slider, fold. 2. Ask for the NFRC U-factor and SHGC for each type with your glass. 3. Ask for VT and air leakage if the maker publishes them. 4. Confirm the rating is for the whole unit, not the center of glass. 5. Check the rating against your city’s energy code and any ENERGY STAR target your builder uses. 6. Keep the label or rating sheet in your project file. ![A farmhouse with a pool at dusk](https://honeyrock.multisites.ai/_astro/dusk-farmhouse-aerial-pool-01.BDzXIkRa_1d5AK0.avif) ## How do I compare two labels side by side? Compare the same rating on both labels, then check the other three. Put the two U-factors next to each other, then the two SHGC numbers, then visible transmittance. Make sure both labels describe the same size, glass and grid. Otherwise you compare unlike products. Jada’s sample table shows why this matters. Its outswing window in the first glass column rates a U-factor of 0.37 and an SHGC of 0.28. Its sliding door in the same column rates 0.37 and 0.32. The U-factors match, but the sliding door lets in more sun heat. Only the SHGC row shows the gap. A simple method works well: 1. Write each rating in a small grid, one product per row. 2. Mark the lowest U-factor and the lowest SHGC in the grid. 3. Check visible transmittance so the lowest SHGC does not leave the room dim. 4. Note any difference in glass, spacer or grid between the rows. 5. Ask the maker to re-rate the product you prefer with the glass you want. If one product has no whole-window rating, treat that as a question, not a pass. Ask why. A rating that covers only the center of the glass leaves out the frame, which in a steel or aluminum window can change the result. ## What does the label not tell me? It does not tell you how a product handles hail, wind-driven rain or a break-in. It does not tell you how a steel frame is finished or how a door sounds when it closes. Those need their own tests and conversations. Air leakage also has a limit. The label shows the product’s own leakage. It does not show how well the window is sealed into the wall. The Department of Energy notes that “good installation practices will minimize air infiltration around fenestration products.” The rating gets you a good product. The install decides how it performs in your wall. Hail is a real issue in North Texas. See the [glass options guide](https://honeyrock.multisites.ai/guides/glass-options-for-windows-and-doors) for what glass type does and does not do in a storm. ## Next step Bring the NFRC ratings for your openings to a conversation with Honey Rock Window and Door. Start with the [energy-efficient windows page](https://honeyrock.multisites.ai/energy-efficient-windows-texas), then use [Start your project](https://honeyrock.multisites.ai/contact-us) or call (214) 484-9982. ## Questions people ask ### What does an NFRC label tell me? It tells you how one window, door or skylight performs for energy. The label can show U-factor, solar heat gain coefficient, visible transmittance and air leakage. NFRC is the independent body that certifies the ratings, so you can compare products from different makers on the same scale. ### Is a lower U-factor always better? For keeping heat in or out, yes. A lower U-factor means less heat flows through the product. But U-factor is only one number. In Texas, SHGC often matters as much, because sun heat is the bigger load in summer. Read both, and check visible transmittance so the room does not get too dark. ### What is a good SHGC for a Texas home? The U.S. Department of Energy says low gain products, with an SHGC under 0.4, are designed for hot climate zones. For a specific target, check the ENERGY STAR climate zone for your address and your city's energy code. Your builder or code official can confirm which one applies. ### Do all windows have an NFRC label? No. NFRC certification is voluntary for makers, and it applies to listed product lines. Always ask for the NFRC rating of the exact product, size and glass you are buying. If a supplier only quotes a center-of-glass number, ask for the whole-window rating. ### Is the NFRC label the same as ENERGY STAR? No, but they are linked. NFRC is the certification body for ENERGY STAR windows, doors and skylights. A product earns ENERGY STAR status when its NFRC ratings meet the limits for your climate zone. A product can have an NFRC label and still not be ENERGY STAR for your zone. ### Where do I find a product's full NFRC ratings? Ask the maker for the NFRC rating for your product type, grid style and glass. Jada points readers to NFRC.org and tells them to look up "Jada, Inc." Your supplier should also give you the rating for each opening on your window schedule. ## Terms on this page - [SHGC (Solar Heat Gain Coefficient)](https://honeyrock.multisites.ai/glossary/shgc) - [Visible transmittance (VT)](https://honeyrock.multisites.ai/glossary/visible-transmittance) - [ENERGY STAR climate zone](https://honeyrock.multisites.ai/glossary/energy-star-climate-zone) - [NFRC label](https://honeyrock.multisites.ai/glossary/nfrc-label) - [U-factor](https://honeyrock.multisites.ai/glossary/u-factor) ## Sources 1. [National Fenestration Rating Council: Home](https://nfrc.org/) 2. [National Fenestration Rating Council: Home (solar heat gain)](https://nfrc.org/) 3. [National Fenestration Rating Council: Home (visible transmittance)](https://nfrc.org/) 4. [National Fenestration Rating Council: Home (air leakage)](https://nfrc.org/) 5. [National Fenestration Rating Council: Home (ENERGY STAR)](https://nfrc.org/) 6. [National Fenestration Rating Council: Residential Product Certification](https://nfrc.org/residential/) 7. [U.S. Department of Energy FEMP: Purchasing Energy-Efficient Residential Windows, Doors, and Skylights](https://www.energy.gov/cmei/femp/purchasing-energy-efficient-residential-windows-doors-and-skylights) 8. [U.S. Department of Energy FEMP: Purchasing Energy-Efficient Residential Windows, Doors, and Skylights (visible transmittance)](https://www.energy.gov/cmei/femp/purchasing-energy-efficient-residential-windows-doors-and-skylights) 9. [U.S. Department of Energy FEMP: Purchasing Energy-Efficient Residential Windows, Doors, and Skylights (air leakage)](https://www.energy.gov/cmei/femp/purchasing-energy-efficient-residential-windows-doors-and-skylights) 10. [Jada Windows: Energy-Values](https://jada.com/features/energy-values) 11. [Jada Windows: Energy-Values (unit values)](https://jada.com/features/energy-values) 12. [Bertrand: About us](https://windowsbertrand.com/bertrand-about-us) Written by Honey Rock Window and Door and checked against the sources above on November 5, 2026. Product specifications and city rules change, so check the linked page before you act. ## Keep reading - [Energy-efficient windows for Texas homesIn Texas, the number that matters most is solar heat gain (SHGC), because summer sun drives cooling costs. Then check U-factor, visible transmittance and the NFRC label. Dallas and Tarrant counties sit in ENERGY STAR's Southern zone. Local energy codes differ by city, so confirm yours.](https://honeyrock.multisites.ai/energy-efficient-windows-texas) - [SHGC and U-factor for Texas: what the numbers should look likeIn Texas, SHGC (how much sun heat gets in) usually matters first, and U-factor (how fast heat leaks through) matters too. The Department of Energy says hot climates need low SHGC. Pick a target from your ENERGY STAR climate zone and your city's energy code, then match it to the rated product.](https://honeyrock.multisites.ai/guides/shgc-and-u-factor-for-texas) - [Glass options for windows and doors: Low-E, argon, triple and laminatedMost exterior glass is an insulated glass unit: two panes with a sealed, gas-filled gap. Low-E coatings cut heat flow, argon slows convection, a warm-edge spacer protects the edge, and laminated or tempered glass adds sound control or safety. Match the package to each wall, then ask for whole-window ratings.](https://honeyrock.multisites.ai/guides/glass-options-for-windows-and-doors) - [Folding and bi-fold doors for Dallas homesA folding door is a row of hinged glass panels that fold flat and stack to one side, opening nearly a whole wall. Jada makes outswing steel folding doors and windows. Bertrand makes aluminum folding systems. Sun makes clad-wood bi-fold doors and windows with Centor hardware. Honey Rock works with all three makers.](https://honeyrock.multisites.ai/folding-doors) - [Steel windows and doors for Dallas homesSteel windows and doors use a thin steel frame to hold large panes of glass. Jada builds them from narrow Secco OS2 thermally broken steel profiles in four families: swing, slide, fold and pivot. A built-in thermal break keeps heat from crossing the frame. Honey Rock Window and Door works with Jada for Dallas projects.](https://honeyrock.multisites.ai/steel-windows-and-doors) - [Thermally broken steel windows: what the break does and what to askA thermally broken steel window has an insulating barrier between its outer and inner steel halves. The barrier slows heat flow through the metal and helps limit condensation. It does not make a window efficient alone. The glass, spacer and installation set the final NFRC numbers, so judge the whole unit.](https://honeyrock.multisites.ai/guides/thermally-broken-steel-windows) ![A modern home with wide glass doors lit warm at dusk beside a pool](https://honeyrock.multisites.ai/_astro/dusk-modern-home-pool-01.CeePxgPr_Z2giQin.webp) ## Let’s frame your view. Send your plans or a few photos of the openings. We will help you choose the system, the brand and the glass. [Start your project](https://honeyrock.multisites.ai/contact-us)[or call (214) 484-9982](tel:+1-214-484-9982)