In California, building efficiency standards are updated on a three-year cycle. The most recent update is set to take effect in January 2014. In an editorial last summer, The Sacramento Bee called the changes implemented in this revision “historic,” because they will vastly improve the efficiency of California’s buildings.
Among the revisions is one that will affect commercial fenestration. The new standard will update the allowable methods for demonstrating energy code compliance for site-built fenestration on nonresidential projects.
Under the new standard, the National Fenestration Rating Council’s (NFRC) Component Modeling Approach (CMA) will be one of two compliance options for U-factor and solar heat gain requirements for nonresidential buildings with more than 1,000 sq. ft. of site-built windows and other fenestration. The other option will remain the default values from the California Energy Commission (CEC). This is a significant expansion of the CMA option from the compliance approaches currently in effect, which require NFRC’s CMA or the CEC’s default values for nonresidential buildings with more than 10,000 square feet of site-built fenestration. Next year, CMA will become the preferred option for many more nonresidential projects.
Benefits of CMA
NFRC, a non-profit organization that rates the energy performance of windows and other fenestration products, created CMA with the goal of simplifying code compliance for site-built or -assembled fenestration. CMA uses a software program that calculates energy performance ratings for nonresidential fenestration. The program allows users to create a product on their computers using performance data from pre-approved glazing, frame, and spacer components to generate whole-product ratings. Once the preliminary ratings have been certified, NFRC issues a single CMA Label Certificate that lists the energy performance ratings for all NFRC-rated products on a given project. This document can be used to demonstrate that the ratings meet energy code requirements.
It has been proven that using CMA instead of CEC’s default values can provide an increase in energy compliance margins. A study in California in 2010 compared CMA values to the CEC’s default and equation-based values, running simulations on eight building models under conditions similar to each of California’s 16 climate zones. The study’s results demonstrated that fenestration modeled with the CMA program could provide an increase in compliance margins by 11.7 percent over the default calculation methods.
With the changes to Title 24’s compliance approaches for site-built nonresidential fenestration, more architects and builders will turn to CMA to demonstrate compliance with energy requirements for windows and other fenestration. To learn more about NFRC’s CMA program, please visit www.nfrc.org/CMA/Default.aspx.