NFRC in the News - Site-Built Fenestration

Architectural West

January/February 2006

Certifying Site-Built Fenestration

Energy Performance Rating & Labeling System

By Jim Benney

When the National Fenestration Rating Council (NFRC) came into being in 1989, we focused first on developing a new rating and labeling system for the energy performance of windows, doors, and skylights used in residential applications. We based that decision largely on the fact that our many stakeholders – those who make, regulate, and buy fenestration products – saw a more immediate need for ratings on products destined for installation in homes. The first certified residential products rolled off manufacturer assembly lines in 1993.

Soon after, our stakeholders turned their attention to fenestration products used in non-residential applications (curtain wall, store front, and the like). A number of factors drove NFRC is this direction:

•  Federal officials recognized the role that fenestration plays in the energy efficiency of commercial buildings. According to one U.S. Department of Energy estimate, for example, roughly 25% of the cost associated with heating and cooling commercial buildings goes right out the window.

•  A number of studies showed conclusively that the use of higher-efficiency products can produce dramatic energy savings. One study by the National Academy of Sciences showed that low-emittance (Low-E) coatings on fenestration products have saved approximately $8 billion in energy costs through the year 2000.

•  Code bodies in numerous states, especially along the West Coast, began to institute codes that called for minimum energy performance requirements for commercial fenestration and that identify NFRC ratings as the principal method to determine U-Factor, solar heat-gain coefficient, and other performance values for the purposes of determining code compliance.

Clearly, the country needed an independent system for rating and labeling the energy performance of fenestration products in non-residential applications. This is the story of how NFRC first approached this challenge, and how we're working to improve on that system today.

Architects Can Serve as the Site-Built “Responsible Party”

NFRC launched its Site-Built Certification Program in 2000. The program adopted many key elements from the residential program, including whole-product performance, simulated ratings validated by physical testing, and independent verification and authorization by a third-party certification entity. Yet the site-built program faced unique issues stemming from the fact that commercial systems are almost always assembled on site.

Most important, NFRC had to determine who would be held responsible for the energy-compliance rating of a finished product. For residential products assembled in a fixed site, the responsible party is clear. Non-residential products involve many different people at many different points along the way, from the curtain-wall supplier; to the glazing contractor; to the general contractor, architect or building developer/owner.

NFRC solved the problem by creating an entity known as the “responsible party” and allowing those involved in the construction process – architects, specifiers, building owners, glazing contractors, installers, and lineal suppliers – to decide who that would be. The responsible party differs from job site to job site, although in practice we have found that the glazing contractor typically plays the role.

Another issue stemmed from the use of NFRC labels. These labels are relatively easy to apply in residential applications, because they can be printed and affixed at the end of the assembly line just before the window is packaged for shipment. Doing the same for site-built products would be impractical. Commercial buildings often feature many different products, some of which may be installed in dozens or hundreds of places. Imagine a code inspector having to check labels on every product installed in a 40-story high-rise.

To get around this problem, the NFRC site-built program allows the responsible party to use a Label Certificate. The Label Certificate is standardized and features the U-factor, SHGC, visible transmittance, and air leakage of the certified site-built fenestration products. One Label Certificate can be used to cover all site-built products of identical construction, so perusing numerous labels isn't necessary. The Label Certificate must be posted on the construction site to serve as code compliance documentation.

Site-Built Process Seeks Simplicity

We designed the site-built process to be as simple as possible, to save both time and money. On average, it takes roughly three to four months to obtain a Label Certificate, depending on the complexity of the project. Manufacturers that serve as the responsible party should have Label Certificates for specific products prior to site assembly. For architects and others who serve as the responsible party, the certificates can be obtained by either:

•  Providing test and simulation reporters to an independent certification agency (the IA) for specific products on the project.

•  Requesting a specific NFRC-certified product from the supplier or contractor and then contacting an IA

•  Asking the supplier to provide a test and simulation report for a product to be accredited by a laboratory in accordance with NFRC 100.

NFRC maintains curtain wall (glazed wall) systems in its online Certified Products Directory at www.nfrc.org/directory in real time. NFRC continually strives to improve its programs. We are now working on an enhanced non-residential rating system that's intended to make compliance for site-built fenestration even simpler and to provide additional value for the user, especially architects.

At the heart of the new system is what NFRC calls the “component modeling procedure.” The procedure breaks down a fenestration system into its component parts (e.g., glazing, spacer, frame cross-sections) and rates each separately. In the end, the final integrator (the glazing installer, architect, or specifier) can obtain whole-product ratings by using component information and an NFRC-approved integration tool.

The component modeling approach is very much a work in progress. NFRC must make a number of important decisions before it can be used, and we encourage architects to get involved. We want to hear from those who will actually use the new site-built procedure so we can be sure that we're designing it to be as simple and effective as possible.