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Glazing Information

Information For Glass Manufacturers, Fabricators and Distributors On the NFRC Site-Built Program


In 1999, NFRC approved a new certification and rating program for site-built fenestration systems including curtain wall, storefront and sunroom systems. The program utilizes many of the tools of the certification program for residential windows, doors and skylights, including computer simulations and third party verification of performance. It has new processes, however, to address the special needs of fenestration products in commercial building applications. These new features include a Label Certificate for the building project (rather than a temporary label on each lite of glass) and a "responsible party" who works with NFRC representatives to obtain the fenestration system ratings. Additional information regarding the Site-Built program can be found in the Guidelines for the NFRC Product Certification Program For Site-Built Fenestration Systems and the NFRC PCP-2007.

How is the glazing supplier involved in the Site-Built Program?

An architect or contractor typically specifies the glass or glazing in-fill for commercial buildings. If the building project requires window-cross-sectioncertified ratings for the fenestration system, the optical properties of the glass/glazing material (reflectance, transmittance, emittance) must have been determined in accordance with NFRC 300 and listed in the NFRC spectral data library.

How does the glass or glazing get listed in the NFRC Spectral Data Library?

A verification procedure has been developed by NFRC that describes the steps needed for listing spectral data. In general, these steps include participating in an NFRC Round Robin; determining the representative data for the selected glazing; submitting that data to NFRC for screening and peer review and paying the appropriate fees for NFRC listing. The process takes about three weeks. A complete listing of the NFRC spectral data library is available --> NFRC Spectral Data Library and a copy of the Verification Procedures, NFRC 302. For additional information on the Spectral Data Program, contact the staff at NFRC headquarters.

Do all glazing systems have to be listed in the spectral data library?

No, only the glass, pvb, or other glazing layer used in a glazing system must be listed. The NFRC verified glazing layers are combined in the WINDOW software to calculate the center-of-glass performance values (U-factor, Solar Heat Gain Coefficient, Visible Transmittance, UV Transmittance, etc.) Please note that glazing suppliers can choose to list specific glazing systems, if desired.

Does the glazing supplier need to be certified?

The only party that must provide certified ratings and sign a license agreement with NFRC is the "responsible party." The responsible party must follow the certification program requirements in order to obtain a Label Certificate. A glazing supplier may be the responsible party, but they must know the type of framing system and have access to the thermal performance characteristics of that system, in order for the entire fenestration system to be rated. Typically, the responsible party is the glazing contractor or curtain wall manufacturer.