Unlike typical, mass-produced residential window products, commercial (non-residential) fenestration systems use a variety of components (glass, spacer and frame) to meet different energy-performance characteristics demanded from project to project. To make it easier to rate and certify the energy performance of non-residential fenestration products, the Greenbelt, Md.-based National Fenestration Rating Council (NFRC) operates a commercial rating and labeling program called the Component Modeling Approach (CMA) Product Certification Program. In addition to meeting the needs of the commercial fenestration industry, the CMA provides many benefits to the design and construction sector.
The CMA program generates U-factor, solar heat gain coefficient (SHGC) and visible transmittance (VT) values according to NFRC 100/200 procedures. NFRC 100/200 is required by the International Energy Conservation Code (IECC), ASHRAE 90.1, California’s Title 24 energy code and U.S. ENERGY STAR residential window program. No other window energy rating and labeling program is referenced in any U.S. energy-code document. In addition, Canada’s Ontario and British Columbia provincial energy codes make reference to the NFRC energy rating method. The U.S. Green Building Council’s LEED requires ASHRAE 90.1-2010 as a mandatory minimum, making NFRC ratings a requirement for any LEED project.
How NFRC Commercial Energy Ratings Work
NFRC’s 800-plus members and participants from all over the world, including manufacturers, suppliers, laboratories, representatives from consumer groups, and the building and code industries, spent years carefully developing the CMA program to ensure it is fair and credible. Since the 2009 CMA inception, NFRC has provided label certificates for more than 300 commercial projects and uploaded more than 4,000 frame components, 200 spacer components and 3,000 glazing components, enabling ratings for a wide variety of commercial projects.
The NFRC commercial rating program uses a new approach to produce reliable, third-party energy-performance data for the bidding process, energy-code compliance and building energy analysis. The new approach centers on assembling products using pre-defined and -approved fenestration components to generate final, whole-product energy ratings. The approved fenestration components’ (glazing, frame and spacers’) energy-performance data are found in online libraries within the program’s energy simulation tool, known as CMAST, or component modeling approach software tool. Together, these data are used to generate certified whole-product performance ratings for U-factor, SHGC and VT according to NFRC 100/200.
Anyone can use the Commercial Product Certified Products Directory of approved fenestration ratings by visiting the NFRC website and selecting “Verify Ratings” in the top navigation and then “Commercial” from the dropdown menu. Anyone can also access the component libraries containing NFRC-approved thermal-performance data for glazing, frame and spacer components.
CMAST is web-based and client-based. Architects, designers, engineers and other users can create virtual fenestration products for non-residential buildings using this program and the online component libraries. The libraries are shared with all users, but users can restrict access to components and projects under development.
Users can quickly see how changing one component affects the energy performance of the entire product. CMAST allows users to compare not only performance of different fenestration systems before making a choice, but it also can show how design changes affect the whole building’s energy performance. In fact, CMAST has an option to export data for use in the building-energy analysis program from the Washington-based U.S. Department of Energy, EnergyPlus. Providing more information about fenestration energy performance can help architects make informed choices when designing sustainable commercial projects.