Decoding Window Labels: What NFRC, NOA, and Impact Ratings Actually Mean

Walk into any window showroom and you'll encounter a wall of acronyms: NFRC, NOA, PGT, CGI, HVHZ, SHGC, VT, U-Factor. These aren't marketing — they're testing and certification references that describe real, measurable performance characteristics. Here's what each one means and why it matters for a Florida home.

NFRC Label

The National Fenestration Rating Council label appears on every certified window and provides standardized performance data:

• U-Factor — How much heat transfers through the window assembly. Lower is better in all climates. In Florida, look for 0.30 or below; 0.25 qualifies for Energy Star Most Efficient.
• Solar Heat Gain Coefficient (SHGC) — What fraction of solar radiation enters as heat. In Florida, lower is almost always better. Look for 0.25 or below. Energy Star Most Efficient in our climate zone requires 0.22 or below.
• Visible Transmittance (VT) — What percentage of visible light passes through. Higher means more natural light. Good Low-E glass balances low SHGC with reasonably high VT (0.35+).
• Air Leakage — How much air passes through the window assembly. Lower is better. Look for 0.30 or below.

NOA — Notice of Acceptance

The NOA is issued by Miami-Dade County's Building Products Approval Division after a product has passed HVHZ (High Velocity Hurricane Zone) impact and pressure testing. An NOA number on a window or door means it's been tested to the most stringent hurricane standards in the country. Products with a valid NOA are accepted throughout Florida as meeting impact requirements, even outside Miami-Dade.

When we quote a product, we can provide its NOA number so you can verify it independently at the Miami-Dade Product Control website.

Florida Product Approval

Products without an NOA can still be used in Florida if they carry a Florida Product Approval (FL number) issued by the Florida Building Commission. This is a state-level certification that the product has been evaluated and meets Florida Building Code requirements for the specified wind zone.

ASTM Testing Standards

Impact window testing references ASTM E1886 (the test method for impact and cyclic pressure) and ASTM E1996 (the performance standard that specifies required test conditions based on wind zone). "Tested to ASTM E1886/E1996" means the specific tested assembly passed those protocols — not just that the manufacturer claims it would.