Michigan § 125.1513f - Log walls; requirements.

Log walls are permitted in residential buildings if all of the following requirements are met:

(a) The log walls have a minimum average wall thickness of 5 inches or greater.

(b) The log walls comply with the international code council standard on the design and construction of log structures, ICC 400-2007, or other successor standard that the department may specify by rule.

(c) The area weighted average U-factor for fenestration products in the log walls is a maximum of 0.31.

(d) All energy efficiency requirements of this act and rules promulgated under this act applicable to components other than log walls are met.

(e) The building heating equipment is qualified under the energy star program jointly operated by the United States department of energy and the United States environmental protection agency as provided for in 10 CFR part 430 or the building heating equipment meets or exceeds the following United States department of energy ratings:

(i) For a gas furnace, an annual fuel utilization efficiency (AFUE) of 90.

(ii) For an oil furnace, an annual fuel utilization efficiency (AFUE) of 85.

(iii) For a boiler, an annual fuel utilization efficiency (AFUE) of 85.

(iv) For a split system air source heat pump, an 8.2 heating seasonal performance factor (HSPF).

(v) For a closed loop water-to-air geothermal heat pump, an energy efficiency rating of 14.1 and a coefficient of performance of 3.3.

(vi) For an open loop water-to-air geothermal heat pump, an energy efficiency rating of 16.2 and a coefficient of performance of 3.6.

(vii) For a closed loop water-to-water geothermal heat pump, an energy efficiency rating of 15.1 and a coefficient of performance of 3.0.

(viii) For an open loop water-to-water geothermal heat pump, an energy efficiency rating of 19.1 and a coefficient of performance of 3.4.

(ix) For a direct geothermal exchange, an energy efficiency rating of 15.0 and a coefficient of performance of 3.5.