How to Read a Window Test Report: NFRC, AAMA, Intertek and CSI
A window quotation usually arrives with a folder of PDFs. They look similar, and they are not interchangeable. This is the short version of what each document tells you — and what it does not.
NFRC: the numbers on the label
NFRC ratings describe thermal and optical performance of a specific assembly: U-factor (how fast heat escapes), SHGC (solar heat gain), visible transmittance (how much daylight comes through) and air leakage. The critical detail is that ratings belong to a whole assembly — frame, glass, spacer and gas fill together. Change the glass and the rating changes.
So when you compare two quotes, compare the ratings for the exact configuration being offered, not the headline number on the brochure.
AAMA: what the window survives
AAMA standards are performance tests rather than ratings: structural load, air infiltration, water penetration and, where applicable, forced-entry resistance. These are the tests that decide whether a system is appropriate for a high-rise or a coastal site, where design pressure is not negotiable.
If your project has an engineer specifying a design pressure, this is the document they will ask for.
Intertek and CSI: who tested it and what class
Intertek is an independent testing laboratory — a report from them means a third party witnessed the test rather than the factory self-declaring it. CSI (Class A) reports relate to the applicable classification for the tested assembly. Neither replaces NFRC ratings or AAMA performance data; they tell you how the result was obtained.
Five questions worth asking
- Which exact system and glazing build-up does this report cover?
- Is this a certificate, or a test report? Who issued it and when?
- Does the tested size match the size I am ordering?
- Was the test witnessed by a third party?
- Does my project's design pressure fall within the tested range?
A supplier who can answer these quickly is usually telling you the truth. If the answers drift, the folder of PDFs is not worth much.
Need this checked against your project?
Send us your drawings or the code requirement — our engineers reply within 12 hours.
