One Set of More Stringent Energy Requirements

Julie Ruth
January 1, 2011
COLUMN : Code Arena | Codes & Standards

Prior to the International Code Council final action hearings in October 2010, indications were that the energy conservation provisions of the 2012 International Codes might contain more than one set of prescriptive values for fenestration. Specifically, during the initial ICC code development hearings in Baltimore in 2009, one set of energy performance criteria was approved for residential construction under the International Energy Conservation Code, and a very different set was approved for the International Residential Code. The set approved for the IECC consisted of one maximum U-factor for fenestration in each climate zone, while the set approved for the IRC consisted of up to four different paths of compliance for each climate zone, with different maximum U-factors, in combination with different maximum SHGCs, for the various compliance paths.

The potential net effect of these multiple sets of requirements would have been confusion for the builders attempting to build in accordance with the code and for code officials who are charged with enforcing the code, as well as for window and door manufacturers trying to provide code compliant products. The extent of confusion this would have caused was recognized during the ICC Group B- hearings this past October in Charlotte, N.C.

The ICC active members gathered there disapproved the second set of values that had previously been approved for the IRC. They then went on to approve a proposal that completely replaced the energy efficiency requirements of the IRC with the requirements of the IECC for residential construction. This later action will hopefully reduce the possibility of this type of confusion occurring in future International Codes. The net result for vertical fenestration and skylights in residential construction is given in Figs. 1 and 2.







Fig. 1–Maximum U-factor and SHGC for residential vertical fenestration in 2012 IECC/2012 IRC








Fig. 2–Maximum U-factor and SHGC for residential skylights in 2012 IECC/2012 IRC

More Stringent
It should be noted that, for the most part, all of the values approved were more stringent than those contained in the 2009 IECC. It was anticipated that this would need to be so to achieve the U.S. Department of Energy’s goal that homes built under the 2012 IECC would use 30 percent less nonrenewable energy than homes built under the 2006 IECC. Although an official ruling from the DOE has not yet been issued, many of the parties who participated in the ICC hearings expressed confidence that this goal had been met by the action taken there.
In addition to the reduction in maximum U-factor and maximum SHGC for residential fenestration, some of the other changes approved for the 2012 International Codes of significance to our industry were as follows:

  • Previous provisions that permitted impact resistant fenestration to have higher U-factors or higher SHGC in southern climate zones were removed.
  • The maximum U-factor for vertical fenestration in thermally isolated sunrooms in Climate zones 4 to 8 will be 0.45, and for skylights in the same climate zones will be 0.70.
  • The previous reference to “metal framed” and “framing materials other than metal” in the prescriptive provisions of the IECC for fenestration in commercial buildings will be replaced by separate requirements for maximum U-factor of fixed windows and operable windows. A third set of requirements for entrance doors will be maintained. The new set of maximum U-factors for fenestration in commercial buildings is shown in Fig. 3.

Fig. 3–Maximum U-factor for commercial fenestration in 2012 IECC

Other changes coming with the 2012 IECC include a reduction of the maximum air leakage rate for fenestration in commercial buildings to 0.2 cfm/sq. ft. for skylights without condensation weepage openings, as well as windows and doors when tested at 1.57 psf in accordance with AAMA/WDMA/CSA 101/I.S.2/A440 or NFRC 400. The 2009 IECC refers to AAMA/WDMA/CSA 101/I.S.2/A440-08 for the establishment of maximum air leakage rates for fenestration. This standard establishes a maximum air leakage rate of 0.3 cfm/sq. ft. for R, LC, CW and some AW rated operator types, and 0.1 cfm/sq. ft. for other AW operator types. The maximum air leakage rate for skylights with condensation weepage openings in commercial buildings will be 0.3 cfm/sq. ft. in the 2012 IECC.

Updated References
The reference to AAMA/WDMA/CSA 101/I.S.2/A440 North American Fenestration Standard/Specification for Windows, Doors, and Skylights will be updated from the 2008 edition to the 2011 edition, pending the completion of that revision by the three applicable agencies (AAMA, WDMA and CSA). The reference to ASTM F2090 Specification for Window Fall Prevention Devices with Emergency Escape (Egress) Release Mechanisms and ASTM F2006 Standard/Safety Specification for Window Fall Prevention Devices for Non-Emergency Escape (Egress) and Rescue (Ingress) Windows will also be updated from the 2008 edition to the 2012 edition. The 2010 edition of ASTM F2090 contains less vague testing requirements for Window Opening Control Devices than the previous edition. Window Opening Control Devices will be permitted to be used as an alternate to 24 or 36 inch high window sills under the 2012 IRC (24 inches) or IBC (36 inches).

AAMA 450 Voluntary Performance Rating Method for Mulled Fenestration Assemblies will be updated from the 2006 edition to the 2009 edition, and AAMA 506 Voluntary Specifications for Hurricane Impact and Cycle Testing of Fenestration Products will be updated from the 2006 edition to the 2008 edition.

Finally, the 2012 edition of IECC also adds a definition and criteria for the determination of Visible Transmittance. VT is to be determined in accordance with NFRC 200 or by the default table given in Table 1.

 Single-Glazed ClearSingle-Glazed TintedDouble-Glazed ClearDouble-Glazed TintedGlass Block
Default VT0.

Table 1

“Does your product meet energy code?” That could have been a tough question to answer if ICC had continued down the path it started.  Manufacturers would have had to say something like “that depends upon whether you are talking about the IRC or the IECC, and if the IRC, which climate zone and compliance path the home is being built to.” 

Try saying that one three times fast. Don’t even think about how you would have explained it to your customers.  Fortunately, you won't have to.  That was not the final result.  Requirements may be more stringent in the 2012 IECC, but there is only one set.


Code Arena is brought to you by the America Architectural Manufacturers Association. Julie Ruth may be reached through AAMA at 847/303-5664 or via e-mail at