- Evolution of NFRC’s Component Modeling Approach Programs
June 15, 2017
Evolution of NFRC’s Component Modeling Approach Programs
In an NFRC-related presentation, Joe Hayden (Pella) focused on the Component Modeling Approach (CMA) Program and its methodology for rating the thermal performance of commercial products.
The CMA program has experienced minimal market penetration to date, representing only 0.14 percent of eligible commercial buildings. Reasons for this low performance include the complexity of the commercial market, the lack of code enforcement, confusion over code requirements, preference for low bids, importance of aesthetics and low confidence due to reported inconsistent results among users.
As a result, a collaboration among AAMA, GANA, IGMA and NFRC will be pursuing a consulting group’s recommendation to implement a single program for both residential and non-residential, thus eliminating confusion and streamlining the certification process.
As part of the proposed change, a “Residential Component Based Calculation” (RCBC) methodology based on statistical trend lines is under consideration. The essence of the process would be to exploit the linear relationship between center-of-glass (COG) and whole product values to potentially define a simple calculation that determines whole product values by just entering COG values. Details of the RCBC proposal are set forth in a white paper available here.
Factors that are likely to introduce complications that must be addressed include differences in frame profiles (e.g., reinforced vs. unreinforced), number of glazing layers, differences in spacer systems, room-side Low-E coatings and use of true divided lites (TDL).
Hayden also reported that the NFRC/ENERGYSTAR® Independent Verification Program (IVP), in which products are randomly selected for U-factor evaluation, is auditing (through 2016) at the rate of 10 percent of product lines each year. EPA has reduced this to five percent for 2017, possibly due to the low rate of failures which hovers around 1.3 percent.