IECC: Easier to Use and Enforce

November 01, 2004
November/December 2004
A version of this article appears in the November/December 2004 issue of Home Energy Magazine.
Click here to read more articles about Codes and Standards

        The International Codes Council (ICC) recently approved sweeping changes to the residential chapters of the International Energy Conservation Code (IECC), the national model code that is the basis for many state energy codes.The revised residential energy code replaces chapters 3–6 of the previous code. It shrinks the IECC code book by more than half, resulting in a code that will be easier to read, understand, use, and enforce.
        The changes will become the 2004 Supplement to the 2003 IECC and the corresponding energy chapter of the International Residential Code. Here are some highlights of the revisions:
        • Redefined climate zones (see above). The new code defines climate zones geographically, reducing their number to 8. (The previous code had 19 climate zones, defined by degree-day ranges.) Compliance and enforcement will be simpler because the new climate zones honor political boundaries, such as state and county lines, and attempt to keep metropolitan areas together.The redefined climate zones also do a better job of integrating cooling considerations into the code—a key improvement, given that air conditioning is a rapidly growing residential load.
        • Simpler prescriptive requirements. Glazing requirements are independent of window area percentage, eliminating the vast majority of the calculations needed to show compliance and significantly reducing the time required for plan reviews and inspections. Each climate zone has a single, stricter, U-factor for windows, regardless of glazing percentage.
        Other changes include caps on window U-values when performancebased design is used; requirements for sealed air handlers; vapor barrier changes; and elimination of unused, redundant, or conflicting definitions.
        Because of the extensive changes, the 2004 Supplement will include a printed copy of the entire IECC, rather than just the changes.The 2004 Supplement can be ordered through the ICC Store at

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