If you’re in the market for new windows for your home and business in the US, you’ve likely come across the NFRC, a council that provides energy ratings for windows, doors, and skylights. In this quick article, we’re going to explain everything you need to know about NFRC and NFRC ratings, and how they’re important for your shopping experience.
NFRC Explained
What is the NFRC?
NFRC stands for National Fenestration Rating Council. If you’ve never heard of fenestration, don’t worry — for our purposes it means windows, doors, and skylights.
What does the NFRC do?
The NFRC provides energy ratings for windows, doors, and skylights with regard to their energy efficiency, or energy performance. In other words, they provide a standardized measure for how good your doors and windows are at preventing heat transfer from the interior to exterior of your home or business and vice versa.
This way, builders, homeowners, and state and local regulators have a quick and easy way to understand how installation of a particular door or window will impact a building’s overall energy efficiency, which is important when setting and abiding by standards to reduce energy costs while creating comfortable places to live and work.
What is an NFRC Rating?
An NFRC rating scores a window or door's energy performance across five metrics:
- U-factor — how well the whole assembly resists heat transfer. Lower is more insulating.
- Solar Heat Gain Coefficient (SHGC) — the fraction of solar heat that passes through. The ideal value depends on your climate: lower in hot regions, higher can help in cold ones.
- Visible Transmittance (VT) — how much daylight passes through. Higher means more natural light.
- Air Leakage — how much air passes through the assembly. Lower is better; 0.3 cfm/ft² or below is considered energy efficient.
- Condensation Resistance (CR) — a 1–100 score for how well interior surfaces resist moisture buildup. Higher is better.
These values appear on the NFRC label that ships with a certified product. For the certified U-factor, SHGC, VT, air-leakage, and condensation-resistance figures on PINKYS steel assemblies — and what each one means specifically for steel, which conducts heat differently than wood or vinyl — see our NFRC ratings page.
Are all windows NFRC Rated?
No, not all windows receive NFRC ratings. NFRC Ratings are only given after a manufacturer submits their window designs to a certified testing laboratory for review. The windows then undergo both computer-simulated and real-world evaluation in order to determine what their ratings will be.
NFRC ratings are a prerequisite of ENERGY STAR certifications, so all ENERGY STAR windows will also have an NFRC rating.
Why are NFRC Ratings Important?
NFRC ratings are important for two main reasons.
First, they enable consumers to shop informed and with confidence. By understanding NFRC ratings and the factors that affect them, you can rest easy knowing you’re buying a product that has been third-party certified to meet high energy efficiency standards.
Doors and windows are a costly, long-term investment, and not easily or conveniently replaced. Being able to understand a product at a glance, as well as compare it to others in the same category makes the shopping experience much smoother.
Second, having a standardized measure for energy efficiency across the US allows state and local agencies to set minimum requirements that protect consumers, reduce energy costs both at home and on the grid, and help to reduce the impacts of cooling and heating on the environment.
NFRC Requirements and Title 24
In California, NFRC-certified values are what document a window or door's energy performance for Title 24 (Part 6, the California Energy Code) compliance. The specific U-factor and SHGC limits vary by climate zone — California has 16 — and are updated each code cycle, so rather than list figures that go out of date, we keep the current requirements broken out by zone on our Title 24 compliance page. The key point for shoppers: NFRC certification is what makes a product's ratings usable for that compliance in the first place.
FAQs
What is a good NFRC Rating?
It depends on the metric and your climate. For U-factor, lower is always better — more insulating. For SHGC, the ideal depends on region: lower in hot, cooling-dominated climates; higher can be beneficial in cold, heating-dominated ones. Higher VT means more daylight, lower air leakage means fewer drafts, and higher condensation resistance means less interior moisture. Because "good" is ultimately defined by your local energy code and climate zone, see our NFRC ratings page for certified values and the code thresholds by zone.
What does NFRC certified mean?
An NFRC-certified window or door is one that has been voluntarily submitted by its manufacturer for testing by an accredited third-party laboratory for energy efficiency. It receives ratings for solar and non-solar heat transmission, transmission of visible light, air leakage, and resistance to condensation.
What is the difference between NFRC and ENERGY STAR?
NFRC is the organization that independently tests and certifies the energy performance of windows, doors, and skylights — it produces the ratings. ENERGY STAR is a label from the US EPA and Department of Energy identifying products that meet energy-efficiency thresholds, and for fenestration those thresholds are met through NFRC certification. So NFRC provides the certified numbers; ENERGY STAR sets the performance cutoffs — which vary by US climate zone — that a product must hit to earn the label. For the current ENERGY STAR thresholds by climate zone alongside PINKYS' certified values, see our NFRC ratings page.
Bottom Line
The National Fenestration Rating Council (NFRC) and the ratings they provide are a crucial tool helping consumers make informed decision about the energy efficiency of their doors and windows. Understanding NFRC ratings can make the door and window buying process smoother and lead to fewer regrets when buying these long-term investments in your home, especially in states like California where Title 24 sets minimum standards for overall energy efficiency.
