NA6.1      Scope

This procedure provides non-rate site-built fenestration up to 1000 ft2 other than a repair or replacement glass an option to comply with the Energy Standards. The Center of Glass (COG) values are required to be used in Equation NA6-1, NA6-2 and NA6-3 and shall be determined by the manufacturers in accordance with NFRC procedures. A copy of the manufacturers’ cut sheets or data sheet shall be provided identifying the COG values as an attachment with the Fenestration Certificate (FC-1).


For Nonresidential site-built fenestration up to1,000 ft² in area, other than repair or replacement glass, the Alternate Default Fenestration Procedure shall be used when no NFRC Label Certificate is available. The manufacturer cut sheet or data sheet shall be used to identify the COG values for the U-factor, Solar Heat Gain Coefficient (SHGCC) and Visible Transmittance (VTC). If unable to determine center of glass information, the alternative Energy Commissions Default Tables in Section 116 of the Energy Standards must be use to determine the appropriate fenestration default values. The values 'listed in Table 110.6-A for SHGC values are whole fenestration product values. Since there is no default Visible Transmittance values available, the alternative is; VTC =1.0 and will be use to determine the total fenestration product, VTT, which includes the glass and frame of the fenestration.

For Nonresidential the altered fenestration other than a repair shall meet the values 'listed in Table 141.0-A unless the altered glass area meets the Exception to Section 140.1(b)2A in the Energy Standards. If the altered fenestration or glass alone is not rated by NFRC then the Alternate Default Fenestration Procedure can be used similar to Nonresidential up to 1000 ft² as described above.


For Residential special cases, the Alternate Default Fenestration Procedure option is available only when non-rated site-built fenestration is being installed in a residential dwelling. For Residential site-built fenestration up to 250 ft² in area or 5% times the conditioned floor area (CFA) whichever is greater shall meet Sections §110.6(a)2 and §110.6(a)3.

The Alternate Default Fenestration calculated values are typically less efficient than those 'listed in Prescriptive Approach in Table 150.1-A of the Energy Standards and may not comply, alternatively the Performance Approach will have to be used to meet energy compliance. The Visible Transmittance (VT) value is not required to meet residential energy compliance. If unable to determine center of glass (COG) thermal performance values from the manufacturer, then alternatively the Energy Commissions Default Tables shall be used; Table 110.6-A for U-factors and Table 110.6-B for SHGC values and documented on the on a self produced manufactured default label.  The default label should be attached to the unrated fenestration product.  An example of the label can be found in the Residential Compliance Manual.


1.   The Energy Commission's FC-1 Label Certificate Form for nonresidential application shall be use to document the Alternate Default Fenestration calculated values for each non-rated site-built fenestration; or  

2.   For residential, a manufactured Default Label attached to each non-rated site-built fenestration.


The equations 'listed below are to be used for only for unrated site-built fenestration that meets the requirements in either item 1 or 2 above.