U-Factor Subcommittee Closes First Day of NFRC's Virtual Meeting by Tackling Five Ballots

Led by Mike Thoman, the U-factor Subcommittee took action on five ballots late this afternoon.

NFRC 100 Product Grouping Ballot

This ballot is a revision to the NFRC 100, Section 4.2.4 and 4.2.4.1.

Section 4.2.4 identifies the possible product groupings and determination of the Group Leaders via a hierarchy.  Section 4.2.4.1 is currently the grouping determination for Center-of-Glass (COG). This ballot proposes a change to the hierarchy that determines the grouping.

Currently frame groupings are done after all other groupings, which may result in simulating total products for multiple frame options when grouping spacer systems. The results of these different simulations will be different but the relationship between spacer systems will not change.

To simplify this process, the ballot changes the hierarchy so frame grouping takes place before spacer system grouping.

The ballot sets forth language to establish a hierarchy of spacer options to use when conducting the frame grouping process. The intent is to reduce the number of simulations required to establish the relationship of multiple frame options.

A motion to accept the ballot with editorial changes and implement it upon publication was approved, 33-0.

NFRC 100 Sightline Ballot

In this ballot, the Sightline Tolerance TG seeks to simplify a procedure for rating products with multiple sightline dimension options within a product line.

In part, this ballot will add a new section that allows manufacturers to establish sightline U-factor groups for products with sightline differences due to frame/sash base profile variations.The group leader is the individual product in the group with the highest total product U-factor.

Following a motion to implement an editorial change, the motion passed 33-0.

NFRC 100 Dynamic Glazings Ballot

This ballot concerned the definition of the term “Dynamic Glazing Product.”

As it is currently written, term is defined as follows:

“Any fenestration product that has the fully reversible ability to change its performance properties, including U-factor, solar heat gain coefficient (SHGC), or visible transmittance (VT). This includes (but is not limited to) shading systems between the glazing layers and electronic or electrochemical switchable glass coatings or construction.”

One of the group’s concerns is that it is not clear what the result would be if test reports and ratings were submitted for certification for any dynamic glazing product that does not exactly fit the explicitly included types in the definition.

This ballot was developed to clarify what features define certifiable dynamic glazing products, to give guidance to laboratories and IA’s when presented with other types. 

One comment regarding this ballot is that some of the language may need to be revised once Window 6 – Therm 6 is approved. 

A motion to move the ballot forward to Technical to be implemented upon publication was approved, 29-1.

NFRC 100 Entrance Door Ballot

Multiple Technical Interpretation Requests (TIRs) gave rise to this ballot, which concerns the handling of default frames and sills for steel and aluminum doors, typically not installed in residential homes. 

Upon review of the TIRs on TIPC determined that TI Requests 2011-10 "Steel Swinging Door Slab" and 2011-11 "Aluminum Swinging Door Slab" were introducing new language and would need to be incorporated into the NFRC 100 and balloted for membership approval. 

One concern was to remove the steel door maximum skin thickness (< 0.8mm) requirement. The reasoning here is that there are steel doors with skin thickness greater 0.8 mm used in residential applications.

Accordingly, the concern is that NFRC 100 must not prevent steel doors with skin thickness greater than 0.8 mm from being modeled with the default wood frame and wood/aluminum sill.

A motion to return the ballot to task group for further work passed, 32-1.

NFRC 100 Skylight Appendix A.3

The proposed new Appendix A.3 is patterned after the existing Appendix A.2. It addresses an emerging need by specifiers for project-specific skylight U-factor ratings similar to those available for non-standard window sizes, as described in A.2.

As building codes continue to reduce maximum allowed U-factors for all fenestration products, it is important to allow for non-certified ratings to be made available for skylights at actual installed slopes. 

The skylight U-factor at slopes approaching vertical is typically 20 percent to 30 percent less than that yielded at the standard 20-degrees-above-horizontal slope. This can be critical for code compliance on many projects. It also provides HVAC designers with more accurate data for the building envelope heat loss estimates. In turn, this results in better efficiency levels inherent in selecting right-sized mechanical systems.

One concern is that the ballot does not provide the technical methodology for the simulator to perform the simulations at non-standard slopes. Boundary conditions are only present the THERM for 20 degree.

Therefore, a motion to move this ballot back to the task group was approved, 30-1.