During the last several months, Glass Magazine’s readers have heard a lot about the National Fenestration Rating Council’s site-built procedure, some of it right and some of it wrong. In this article, I will try to bust some of the myths about the program.
1. No workable procedure exists for rating commercial glazing, particularly for products glazed or assembled in the field.
The NFRC 100 standard has been used for commercial fenestration products since 1992; in fact, the city of Seattle has required its use since 1993. The NFRC site-built procedure was developed and approved in 1999 to address curtain wall, storefront and other site-glazed and or field-assembled fenestration systems. It has been referenced in Title 24 of California’s Energy Code since 2001. Since then, literally thousands of fenestration products and systems have been authorized for certification or certified with label certificates in the Golden State.
2. Although NFRC has added a procedure for site-built fenestration, the lack of NFRC labels on curtain wall and storefront fenestration in the field is evidence that the existing procedures are not working for commercial buildings. Most commercial inspectors have never seen a single rating label on curtain wall or storefront windows.
Site-built fenestration systems such as curtain walls and storefronts do not receive labels; rather, they utilize label certificates posted at the building site. Since 1999, NFRC has issued label certificates for thousands of fenestration products. In addition, NFRC has issued certification authorization reports for hundreds of thousands of fenestration products installed in low-rise office buildings and townhouses and high-rise condominiums.
3. When a product is not labeled, the International Energy Conservation Code assigns a default value to that product for U-factors and solar heat-gain coefficients from default tables. U-factor default values for curtain wall and storefront fenestration never meet the code requirements in heating dominated climate zones, and never meet the SHGC requirements in cooling dominated climate zones.
Default values in the codes are meant to be punitive to assure that manufacturers do not get credit for poor performing and inefficient framing and glazing systems. Neither high-performance glazing systems nor thermally broken or thermally improved framing systems can be qualified by a visual inspection, meaning that code inspectors cannot evaluate whether the product is energy efficient. Building code officials need—and desire—labels and label certificates to drive punitive default values. Further, default values can indeed meet energy code when utilizing performance-based approaches for code compliance rather than relying on prescriptive-based methods.
4. Curtain-wall and storefront fenestration systems incorporate many combinations of spacers, glass and framing systems. This leads to a huge number of possible configurations in the final product assembled in the field by the glazing contractor. The NFRC rating system cannot deal with this complexity.
The NFRC rating and certification program easily handles complex fenestration systems. For example, one manufacturer has authorized for NFRC certification more than 30,000 individual product variations within one product line, a vinyl-frame, double-hung window.
5. A new standard is needed to more easily rate commercial products in a realistic, cost-effective and simple manner.
The current NFRC program is already a proven, realistic and cost-effective system. The simplicity of any program or system depends on the understanding of the program participant. New participants find that they are able to negotiate the site-built system with relative ease once they begin to go through it, and NFRC leaders are committed to providing education and assistance to participants. NFRC standards provide a single yardstick for comparing product performance, and NFRC labels and label certificates provide a common language for expressing performance.
6. Providing a new, alternative standard, such as the American Architectural Manufacturers Association’s AAMA 507, for rating fenestration products, will increase enforcement of energy codes.
Having two sets of standards for determining energy performance will actually increase complexity and decrease the ability of code inspectors to determine compliance. Two standards will create confusion because code inspectors will have to determine what label to look for and what standard is being referenced. Just like insulation, with ratings based on R values; air conditioners, whose ratings are based on seasonal energy efficiency ratio, or SEER performance; and lighting efficiency; one standard will be the best way to help code inspectors determine fenestration energy performance and code compliance.
7. Having a new rating procedure, such as that of the American Architectural Manufacturers Association, AAMA 507, will be more cost-effective for the industry and have no cost implications.
The NFRC was actually formed so that the industry would have one fair, accurate and credible way to determine energy ratings for fenestration systems. The industry itself was tired of manufacturers playing games with alternative, competing ratings that gave different results, and federal officials were looking closely at the industry to make sure that the interests of consumers were protected. The term “fair, level playing field” was the battle cry in 1989. In addition, the industry was tired of having to obtain different product ratings for different jurisdictions. By thrusting two alternative rating methods onto the industry, manufacturers will now be forced to obtain both ratings, since they will not know what rating may be required by different jurisdictions.
I hope this exercise will help separate rumor and speculation from truth and fact. Look for additional information about the site-built procedure at www.nfrc.org.