NFRC 200 between glass shading systems ballot

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					                              NFRC 200-between glass shading
                                     systems Ballot –
                                VOTING SUBMITALL FORM

       To:                 NFRC Voting Members
       From:                Jeff Baker-Technical Committee Chair,
                            Jim Larsen-Solar Heat Gain SC Chair
       Date:               June 10, 2006
       Subject:            BALLOT For Your Action: NFRC 200-between glass shading systems- These
                           edits accommodate between glass shading systems in NFRC 200.

       Please fax or mail ballots to Jeff Baker, (c/o NFRC, 8484 Georgia Avenue, Suite 320, Silver Spring, MD 20910.
       FAX: 301-576-5510) on or before July 10, 2006.


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    Please review the balloted items and return the ballot/voting form and any comments on or before the due
                                     date so that a quorum of the ballot can be established
                                      BALLOT CLOSE DATE –         July 10, 2006
This ballot proposes revisions to NFRC 200-2004 that are intended to simplify the rating procedures for
Dynamic Glazing Products with a shading system between glazing layers. It is not believed that this will
in any way change existing rules for other products.

Minor revisions to Sections 4.2.1 and 4.2.2 are proposed to provide a more direct reference to the
corresponding sections in NFRC 100 regarding Product Lines and Individual Products.

The most significant proposal is to add a new Section 4.2.3.C to allow shading systems to be grouped. All
shading systems within a group must be of the same type and design. The only allowable variation within
a group is the color of the shading system. Further, the new Section 4.2.3.C would allow the “darkest”
color shading system within the group to serve as the group leader for purposes of determining SHGC.
The “darkest” color is defined as that color with the lowest L* value per the CIE L*a*b* color scale.

It is important to understand that the L* value is essentially being proposed as a surrogate for
absorptance. I believe it would be desirable to define the shade with the highest absorptance as the group
leader. However in pursuing this, absorptance information does not appear to be readily available from
suppliers of shading systems, whereas L*a*b* values are readily available. Therefore, in the interest of
expediency and simplicity, this proposal is to rely on the L* value to define the group leader.

If you are interested, this URL will take you to an “Applications Note” publication from HunterLab that
provides a nice summary of the L*a*b* color scale: http://www.hunterlab.com/appnotes/an07_96a.pdf

If you have questions on any of these proposed revisions, or would like to discuss them further, please feel
free to contact Joe Hayden at 641-621-6096 (office), 641-780-0591 (cell), or jahayden@pella.com.


Proposed revisions to NFRC 200-2004 ( indicates deletion of existing language, underline indicates new
language added):

        4.2     Product Lines and Individual Products

                4.2.1   Product Lines
                        Refer to Section 4.2.1 of NFRC 100 for the definition of a product line.

                4.2.2   Individual Products
                        Refer to Section 4.2.2 of NFRC 100 for the definition of an individual
                        product. For the purposes of this procedure only, variations in gap width,
                        frame or sash color, and/or gas fill do not constitute different individual
                        products.

                4.2.3   Grouping of Products
                        A.       [unchanged]
                        B.       [unchanged]
                        C.       When rating Dynamic Glazing Products with shading systems
                                 between glazing layers, it shall be permitted to group combinations
                                 of shading systems and glazing layers. For purposes of determining
                         SHGC, the shading system and glazing layers comprising each
                         group leader shall be determined as follows.
                         i.     Shading systems within a group shall vary only by color of
                                the shading systems. The shading system used in the group
                                leader shall be of the darkest color within the group. The
                                darkest color shall be defined as that color with the lowest
                                L* value in the CIE L*a*b* color space, as described in
                                Section 8 of CIE 15.
                                If multiple shading systems within the group have the
                                same, lowest, L* value, then any one of those shading
                                systems shall be permitted to be used in the group leader.
                         ii.    Glazing layers within a group, and the corresponding
                                glazing layers used in the group leader, shall be determined
                                in accordance with the representative glazing pane
                                thicknesses rules of Table 4-1.
                                      Note: It is intended that these same rules shall apply
                                            to determining VT ratings as well, when
                                            procedures for obtaining VT ratings for such
                                            products are approved and implemented.

                   [remainder of Section 4, and all of Section 5, unchanged]



6.   REFERENCES
     [1]   National Fenestration Rating Council. NFRC 100-2004: Procedure for
           Determining Fenestration Product U-Factors, Silver Spring, MD.
     [2]   National Fenestration Rating Council. NFRC 300-2004: Test Method for
           Determining the Solar Optical Properties of Glazing Materials and Systems,
           Silver Spring, MD.
     [3]   National Fenestration Rating Council. Simulation Manual-2004: Silver Spring,
           MD.
     [4]   National Fenestration Rating Council. List of Approved Simulation Programs.
           Silver Spring, MD.
     [5]   ISO 15099 : Thermal Performance of Windows, Doors and Shading Devices —
           Detailed Calculations
     [6]   ASTM C 1172-03: Standard Specification for Laminated Architectural Flat Glass
     [7]   ASTM C 1036-01: Standard Specification for Flat Glass
     [8]   ASTM C 1048-04: Standard Specification for Heat-Treated Flat Glass—Kind HS,
           Kind FT Coated and Uncoated Glass
[9]   CIE 15:2004, 3rd Edition: Technical Report – Colorimetry

				
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