The Michigan Energy Code (MEC) governs energy efficiency for the design and construction of commercial buildings and structures, including residential buildings four stories and taller. The latest version of the MEC, which guides the work the team from Kraemer Design Group is doing, went into effect on September 20, 2017.

Part 10a of the Michigan Act PA 230 of 1972 (officially known as the Stille-Derossett-Hale Single State Construction Code Act) authorizes the Michigan Energy Code. It adopts portions of the 2015 International Energy Conservation Code (IECC) for its administrative aspects, and most of the ASHRAE 90.1 90.1-2013 Standard for technical provisions.

• The total number of pages has increased by 47 percent. The total number of pages in Technical Chapters 5 through 10 has increased by 81 percent. (Only Chapter 5 concerns architectural changes to the building envelope. The other chapters regulate mechanical systems and lighting.)


• One hundred definitions are new or modified from the previous edition.


• Overall, the new ASHRAE 90.1 standard places a greater emphasis on maintenance and operation, and onsite renewable energy generation.


• Air movement through the building envelope is recognized as a significant factor in conserving energy and determining interior air quality, so air barriers must be continuous over all surfaces of the building envelope, including the lowest floor and the roof. Air barriers are to be detailed on the drawings, as are the penetrations of, or the joints between, floors, walls, and roofs. They are to be inspected after installation.


• Air leakage requirements for fenestration have been tightened.


• Prescriptive values for the building envelope, including insulation R-values and fenestration U-values, have been changed to decrease heat loss.


• To prevent heat loss, vapor-retardant swimming pool covers are required unless the heat is recovered or the pool is solar-heated.


• There is a greater emphasis on daylighting. Minimum requirements for skylights have been extended into new areas.

MEC amends or excludes some of the requirements of ASHRAE 90.1 relating to glazing and fenestration replacement, installation of storm windows, insulation, and re-roofing. It also modifies the requirements for vestibules, system commissioning, and lighting alterations.

The MEC addresses existing buildings as follows:

• Additions are to comply with ASHRAE 90.1 Section 4.2.1.2.
• Alterations are to comply with ASHRAE 90.1 Section 4.2.1.3.
• A change in occupancy resulting in increased demand for fossil fuels or electrical energy also must comply with the MEC.
• Repair work in buildings must be done in accordance with IECC C501.3 and Section C504.

Change No. 3
While the MEC includes separate rules for residential and commercial buildings, it considers residential buildings greater than three stories tall to be commercial buildings. Podium buildings, in which 3 to 4 stories of wood residential construction are erected above non-combustible first floor construction, are considered to be commercial buildings by the MEC.