Standard values for outdoor convective surface heat transfer coefficients is listed in Table 4-2; On the indoor side of a fenestration product, detailed radiation model, based on gray body radiation model as described in Section 8.4.2.1 in ISO 15099, shall be used for all products. This model applies to both glass and frame surfaces; The use of detailed radiation model on indoor fenestration surfaces makes the use of “slightly or partially ventilated cavities” on the indoor frame surfaces redundant (see Section 6.7.1 of ISO 15099). The standard frame convective film coefficients (hc) shown in Table 4-2 and detailed radiation model referenced above shall thus be applied to all interior frame surfaces; On the outdoor side of a fenestration product, black body radiation model (as defined in ISO 15099) shall be used. This model applies to both glass and frame surfaces; and All cross-sections shall include 150 mm (6 in) of glazing section from the sightline to the end of the glazing section, while maintaining a 63.5 mm (2.5 in) edge-of-glazing dimension. Table 4-2 – Boundary Conditions Boundary Condition Convective Film Coefficient Boundary Tilt = 90o Tilt = 20o W/m2K (Btu/h·ft2·ºF) W/m2K (Btu/h·ft2·ºF) NFRC 100-2001 Exterior 26.00 (4.578) 26.00 (4.578) Interior Aluminum Frame (convection only) Model 3.29 (0.579) 4.65 (0.819) Interior Thermally Broken (convection only) Model 3.00 (0.528) 4.09 (0.720) Interior Thermally Improved (convection only) Model 3.12 (0.549) 4.32 (0.761) Interior Wood/Vinyl Frame (convection only) Model 2.44 (0.429) 3.09 (0.544) Interior Glazing System boundary condition Model Depends on the WINDOW calculations for the imported glazing system e
Equation 5-3 Where Ut = Total door system U-factor Utr = Top rail U-factor Atr = Top rail area Ubr = Bottom rail U-factor Abr = Bottom rail area Ues = End stile U-factor Aes = End stile area Umr = Meeting rail U-factor Amr = Meeting rail area Udpc = Door panel core U-factor Adpc = Door core area Ueg = Edge-of glazing U-factor Aeg = Edge-of-glazing area Ucg = Center-of-glazing U-factor Acg = Center-of-glazing area Apt = Projected total door system area Figures Figure 5-11 – Garage Door U-factor Area Weighting, Sectional Figure 5-12 – Garage Door U-factor Area Weighting, Elevation View Figure 5-13 – Garage Door Front Elevation View and Perimeter Details
Applied Films [Note: Applied films factory-applied to glazing prior to fenestration product fabrication and installation are already covered as glazing options by ANSI/NFRC 100 and shall not be rated according to the procedure of Section 5.10 below.] Scope This section presents additional details specific to applied films. This section presents and references methods for determining specific applied films U-factor rating. Variations from Standard Product Lines None Variations from Standard Individual Products None Variations from Standard Simulation and Test Conditions Approved Center-of-Glazing Computational Program Approved center-of-glazing software shall be used to determine U-factor. Applied films shall be from the approved NFRC spectral data files with the International Glazing Database (IGDB). Glazing/applied film assembly shall be constructed in accordance with NFRC 304 procedure. The following reference glazing systems shall be simulated with and without the film installed: Single 3 mm (1/8 in) Clear; Single 6 mm (1/4 in) Clear; Single 6 mm (1/4 in) Grey; Double 3 mm (1/8 in) Clear/3 mm (1/8 in) Clear: 7 mm (1/4 in) air gap; Double 6mm (1/4 in) Clear/ 6 mm (1/4 in) Clear: 12.7 mm (1/2 in) air gap; and Double 6 mm (1/4 in) Grey/ 6mm (1/4 in) Clear: 12.7 mm (1/2 in) air gap. The position (surface number) of the film when installed on the glazing system shall be documented (i.e., #1 to #4). This will yield the matrix in Table 5-8 for each applied film and applied film position. Calculation of Total Product Rating The reference fenestration product with applied film U-factor shall be calculated as outlined below.
Table 5-8 – Center-of-Glazing Values Uc Reference Glazing System Without Film With Film Uc Btu/h·ft2·ºF Film Position Uc* Btu/h·ft2·ºF 3 mm (1/8 in) clear 1.04 Interior 6 mm (1/4 in) clear 1.02 Interior 6 mm (1/4 in) grey 1.02 Interior 3 mm (1/8 in) 3 mm (1/8 in) clear 7mm (1/4 in) gap 0.55 Interior 6 mm (1/4 in) clear 6 mm (1/4 in) clear 12.7mm (1/2 in) gap 0.47 Interior 6mm (1/4 in) grey 6 mm (1/4 in) clear 12.7mm (1/2 in) gap 0.47 Interior * Uc ‘with Film’ shall be calculated using reference glazing with film to be rated. Table 5-9 – Values of U-factor for Reference and Applied Films Reference Product U-factor Btu/h·ft2·ºF Operator Type Reference Frame Reference Glazing no film with film* Residential Fixed Aluminum 3mm (1/8 in) clear 1.081 Non-Residential Window-wall Aluminum 6mm (1/4 in) 1.021 6mm (1/4 in) grey 1.021 Residential Fixed Aluminum 3mm (1/8 in) clear 3mm (1/8 in) clear 7mm (9/32 in) gap 0.700 Non-Residential Window-wall Aluminum 6mm (1/4 in) clear 6mm (1/4 in) clear 12.7mm (1/2 in) gap 0.588