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Spring 2001

The Rate Debate


Ratings, Ratings Everywhere

by susan douglas


Certification organizations such as the National Fenestration Rating Council (NFRC) are bringing new performance ratings for windows, doors and skylights to market at a dizzying pace.

For example, last year NFRC added an on-site rating procedure for products in commercial applications and approved technical procedures for rating fading transmittance and condensation resistance. Other organizations have new, non-thermal ratings as well, and they are working on more as this is written.

These new ratings are being driven by a number of factors: efforts by individual states to adopt new building codes and tighten existing ones; manufacturers’ desire to imprint their products with the credibility that comes with third-party certification; and ever-increasing demands from window consumers for more and better information concerning product performance.

NFRC’s Growing Stable of Ratings
Since it can be difficult at times to keep up with the rapid pace of new ratings, I offer as a public service this summary of NFRC’s currently available ratings and those on the way.

NFRC’s procedure for products in commercial applications is now nearly one-year old, and an increasing number of glazing contractors and other responsible parties are taking advantage of this system. The rating addresses products that are field-glazed or field-assembled, including curtainwall and windowwall applications, and sunrooms and solarium systems. Prior to the approval of this rating procedure, these products could not—in the vast majority of cases—be certified through the NFRC system. In response, the states of Washington, California and Massachusetts have adopted new NFRC rating requirements for commercial buildings. Several other states also are considering doing so.

NFRC now offers manufacturers the option of rating and certifying their products for air leakage. We’ve had a technical procedure in place for a long time, and now we have our certification system implemented and accredited testing and simulation laboratories ready to accept product. Unlike our other ratings (U-factor, solar heat gain, and visible transmittance), air leakage is strictly voluntary and manufacturers can choose not to include it on their NFRC temporary labels.

With the technical procedures for fading transmittance and condensation resistance complete, we’re working on certification procedures for both, and hope to have them in place within the next year so manufacturers can begin labeling their products with these more consumer-friendly ratings.
In the future we’re looking at ratings for annual energy performance, long-term energy performance, daylighting and comfort, although some of these require additional research and are way down the road.

New Mandatory Ratings
One important new policy went into effect on January 1, 2001. NFRC now requires all products to be rated and labeled for U-Factor, solar heat gain coefficient (SHGC) and visible transmittance (VT). We took this step for a number of reasons:

• SHGC and VT ratings are necessary to understand the energy performance of fenestration products adequately. In cooling climates, for example, SHGC may be more important than U-Factor in terms of overall product performance;

• A growing number of states are adopting energy codes that include NFRC ratings with SHGC requirements in their building codes;

• Several utility and other voluntary programs, such as the federal ENERGY STAR® Windows Program, require NFRC-certified SHGC ratings.

• As fenestration industry professionals, we should all welcome the trend toward an increasing number of independent, certified fenestration performance ratings. These benefit the manufacturers, regulators and buyers of windows, doors, and skylights equally. The trick is to keep up with all the new products. 

If you would like more information on the ratings offered by NFRC, please visit our website at www.nfrc.org, or call us at 301/589-6372.

Susan Douglas serves as administrator of the National Fenestration Rating Council, based in Silver Spring, Md.


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