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New Training Introduces LEAFF Methodology

Posted By Adriana Vargas, National Fenestration Rating Council, Tuesday, March 31, 2020
Updated: Tuesday, March 31, 2020

By Scott Hanlon 

 

The new term LEAFF, which stands for Linear Energy Analysis For Fenestration, is NFRC’s branding of the trendline methodology work of the Residential Component Based Calculation (RCBC) Task Group over the last 10 years. Online LEAFF training is currently underway and we are close to concluding the first phase. There are two more phases left to attend where you will learn how to determine the formulas for the trendlines and calculate the whole product performance for U-factor and the new Condensation Index rating. The last phase, ending in late May, will provide an update on the changes to the program documents and the requirements for the labs and IAs when providing data, reports, and review for product certification. NFRC also is investigating using the LEAFF methodology for commercial products 

 

Thanks to NFRC staff and task group members, LEAFF is poised to greatly reduce the simulation and testing process time. Of course, our primary goal is to deliver to you, our NFRC members, a beneficial, user-friendly new methodology that maintains our reputation for fair, accurate and credible ratings of fenestration products. 

 

So how does LEAFF work? The Linear Energy Analysis for Fenestration (LEAFF) methodology uses product line characteristics and glazing options to determine multiple trendlines that replace the need to run numerous simulations separately that generates the product’s performance with different options (such as glazing and frame types). 

 

With a new methodology there is always a need for new tools and software updates. NFRC provided LEAFF training attendees with informational files for the first phase of training and more will be coming during the second phase. Staff is also working on an interim process to collect and determine the coldest temperature points in THERM for the Condensation Index rating. The long-term solution is to integrate the collection of the temperatures in THERM and we will be working with Lawrence Berkley National Labs starting in 2021 to begin this process. 

 

NFRC’s Certified Products Directory (CPD) will need to be updated to include the new Condensation Index (CI) rating while we sunset the Condensation Resistance rating. We are working with our IT partners now and will have more to update later this summer. 

 

We do have an implementation plan drafted that requires more attention once we get through the training and the software changes. To review the draft plan, go to the RCBC TG's document webpage. NFRC welcomes your input. 

 

And finally, there will be some updates to the NFRC 700 document that the RCBC TG will need address in conjunction with the NFRC 700 task group. These pertain to the information on the label for the CI rating and the products that are included using the LEAFF methodology. 

Tags:  energy performance  fenestration  methodology 

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