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Michigan Moves Forward With Updated Statewide Residential Energy Code

The Michigan Residential Code Review Committee has voted to approve a new statewide building energy code for residential buildings, with an expected effective date of January 2016.  The new code is based on the 2012 International Energy Conservation Code (IECC), with some modifications listed below.

MEEA has analyzed the economic potential of adopting the 2012 IECC, with the Michigan-specific modifications.  We have found that a newly constructed 2,400 square foot home in Detroit will use an average of 725 fewer kWh and 358 fewer therms per year if built to the 2012 IECC, as modified in Michigan, compared to the current energy code.  This would result in the average homeowner saving around $320 annually in utility bills.  It is important to note that these energy and cost savings will continue for the life of a building, which can be 50 – 100 years or more.

In addition to yielding economic benefits to homeowners, the proposed energy code will result in higher quality, healthier, and more comfortable buildings.  In particular, the requirement for buildings to have air tight enclosures and well-sealed duct systems, verified with diagnostic tests, will help realize these benefits to air quality.  A building enclosure that is tightly sealed, combined with a proper ventilation system, will prevent unwanted movement of air into and out of the building.  This reduces the load on space heating and cooling equipment and increases the indoor air quality of buildings.

The efficiency improvements in the new code include: a requirement for tight building enclosures, tighter duct systems, diagnostic testing to verify the air infiltration and duct leakage rates, higher efficiency windows and added crawl space insulation.  Importantly, all of these measures and their energy efficiency improvements are most easily incorporated during the design and initial construction phase.  It can be cost prohibitive to improve these measures in existing buildings, which is why it is crucial for these measures to be addressed in the building codes that regulate new construction.

Using the median number of one and two family residences built annually over the previous ten years in Michigan (12,915 homes[1]), multiplied by the potential annual energy savings per home in Detroit (37.1 MMBTU), there would be an annual statewide energy savings of around 480,000 MMBTU from building to the new 2012 energy code for residential buildings.  That is equivalent to the amount of energy used by almost 2,500 homes, and utility bill savings would be over $4 Million annually for homeowners.

In 2013, the Department of Licensing and Regulatory Affairs convened the Residential Code Review Committee to address the issue of updating the statewide energy code.  The committee was comprised of code officials and others in the state’s building industry to consider the entire International Residential Code, including Chapter 11 on Energy Efficiency.  MEEA supported this process by providing educational materials to the committee and attending several of the meetings when energy efficiency was on the agenda.  MEEA provided comparisons that showed differences between the current and proposed codes, energy savings analysis, and third party reports from Department of Energy.

Below are the amendments Michigan is planning to incorporate into the residential 2012 IECC:

  1. 1.      Wall Insulation (prescriptive table only):
  • Climate zones 6 and 7: R-20 or R-13 + 5


  1. 2.      Basement Insulation:
  • Climate zone 5: R – 10 / 13


  1. 3.      Ceiling Insulation:
  • Climate zone 5: R – 38


  1. 4.      U-factor Table (R402.1.3):
  • Modified to reflect changes to prescriptive table


  1. 5.       Air Leakage:
  • Requires blower door test to confirm air leakage of less than 4 ACH50 (prescriptive)


  1. 6.      Duct Leakage:
  • Requires duct leakage test when portion of duct system located outside conditioned space. Must meet one of the following leakage requirements:
    • o Postconstruction Test:

Total Leakage: 4 CFM25 / 100 sq ft.

Leakage to Outside: 4 CFM25 / 100 sq ft.

  • o Rough-in test:

Total Leakage: 4 CFM25 / 100 sq ft.