ConstructionPro Week, Volume: Construction Advisor Today - Issue: 121 - 08/18/2011

Nearly Half of All States Have Adopted a Residential Energy Code at Least as Stringent as 2009 IECC

Twenty-one states have adopted a residential energy code that is at least as stringent as the 2009 version of the International Energy Conservation Code (IECC), according to Green Building Insider’s analysis of energy-code information that DOE recently released. The status of each state’s energy-code policy for both the residential and commercial sectors can be accessed through the following link:

The IECC applies to new buildings and to remodels, renovations, and additions to buildings. The code requirements are almost completely different for residential and commercial structures. Residential buildings are essentially defined as low-rise buildings (three stories or less above grade) intended for long-term living (hotels/motels are classified as commercial buildings).


Only California and Arizona have adopted a residential energy code that is more stringent than IECC 2009 while 19 other states’ residential codes are as stringent as IECC 2009. The remaining states’ residential energy codes are not as stringent as 2009 IECC, are different from the IECC, or do not exist.


The IECC had substantial revisions from 2006 to 2009, according to the U.S. Department of Energy (DOE). These revisions were not to the code format but were changes to specific requirements to improve energy efficiency and make the code more stringent.


The 2009 edition includes the following additions:


  • The duct system must be tested, and the air leakage out of ducts must be kept to an acceptable maximum level. Testing is not required if all ducts are inside of the building envelope (for example, in heated basements), though the ducts still must be sealed.
  • Fifty percent of the lighting “lamps” (bulbs, tubes, etc.) in a building must be energy efficient. Compact fluorescents qualify; standard incandescent bulbs do not.
  • Trade-off credit no longer can be obtained for high-efficiency HVAC equipment. For example, if a high-efficiency furnace is used, no reduction in wall insulation is allowed. This will have a great impact on reducing the flexibility allowed by the REScheckTM software, DOE stated.
  • Vertical fenestration U-factor requirements are reduced from 0.75 to 0.65 in Climate Zone 2, 0.65 to 0.5 in Climate Zone 3, and 0.4 to 0.35 in Climate Zone 4.
  • The maximum allowable solar heat gain coefficient is reduced from 0.40 to 0.30 in Climate Zones 1, 2, and 3.
  • R-20 walls in climate zones 5 and 6 (increased from R-19).
  • “Modest” basement wall and floor insulation improvements.
  • R-3 pipe insulation on hydronic distribution systems (increased from R-2).
  • Limitation on opaque door exemption, both size and style (side hinged).
  • Improved air-sealing language.
  • Controls for driveway/sidewalk snow-melting systems.
  • Pool covers are required for heated pools.


Three states -- California, Florida, and Oregon -- have adopted a commercial energy code that is at least as stringent as either IECC 2009 or the American Society of Heating, Refrigerating and Air-Conditioning Engineers’ 90.1 2007 standard. Twenty-three other states have adopted a commercial energy code that is at least as stringent as either of these two standards.


DOE did not immediately respond to GBI’s request for an interpretation of the statistics.



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