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Three More States Tweak Energy Codes

Posted by Mike Collignon

Apr 29, 2014 12:02:19 PM

Energy Code Information: The state’s Construction Code Advisory Council approved a draft energy code based on the 2012 IECC. It then moved to a review by the state’s Department of Labor and Industry. A public comment period was held earlier this year, though the state first has to work through the issue of residential sprinklers. Once they finally get to the energy code discussion, they will review the following amendments proposed to both the commercial and residential codes:

Commercial: The IECC commissioning requirements were incorporated into ASHRAE 90.1-2010, so there is consistency between the code and standard.

Residential: Wall insulation R-value is R-21 for the prescriptive table, while the U-value table remains the same as it was. Ventilation requirements have been increased to balanced ventilation (cannot use exhaust or supply).Two options for basement wall insulation: R-15 continuous or R-10 exterior insulation; however, 2.5 ACH50 must be proven.Elements to ensure basement walls are waterproofed, which helps mitigate moisture damage.

Observation(s): The move to the 2012 IECC by the State of Minnesota represents a notable shift in policy. Historically, they have devised their own energy code, perhaps on the theory that they had colder weather to deal with than most every other state. They have since recognized that the stringency of the most recent energy code will adequately serve their residents.


Energy Code Information:The state has upgraded their energy code from the 2009 IECC to the 2012 IECC. The adoption will become effective in March 2014. Several minor amendments were made. The most disappointing was the retention of the wall R-values from the 2009 IECC.

Observation(s): The “Big Sky” state is joining the growing number of states that have moved closer to the 2012 IECC. While they didn’t implement the full 2012 IECC, at least they didn’t take their wall R-values backwards like…

Energy Code Information: The state’s Department of Public Safety announced they have updated the state’s commercial and residential energy code to the 2012 IECC. It became effective March 12, 2014.

While they did not amend the commercial code, five amendments were made to the residential code. The amendments are as follows:

  • Air Infiltration: Air tightness requirement weakened from 3 ACH50 to 4 ACH50.
    Duct Tightness: Requirements weakened from only total duct leakage of 4 cfm/100 sq. ft. to allowing two options: total leakage of 6 cfm/100 sq. ft. or 4 cfm/100 sq. ft. leakage to outside.
  • Building Cavities: Allows interior building cavities to be used as return ducts; however, if building cavities are used as return ducts, they must be sealed and tested for tightness with the entire duct system (even if all ducts are located within conditioned space).
  • Above-Grade Wall Insulation: Climate Zone 6 prescriptive value lowered from (R-20 + 5 or R-13 + 10) to (R-20 or R-13 + 5); U-factor table remains unchanged.
  • Exempts additions and renovations from the code.

There was no opposition to these amendments.

Observation(s): We expected their residential energy code to fall somewhere between the 2009 and 2012 IECC. It’s just disappointing that in a windy state like Iowa, the DPS decided to reduce the amount of required insulation in the above-grade walls. There was no need for that, and it will only make it more difficult for the state’s builders to adjust when the 2015 IECC arrives.

Building Codes Assistance Project (BCAP)
Midwest Energy Efficiency Alliance
Iowa 2012 IECC Amendments

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