2012 IECC with Montana amendments

Source: International Energy Agency
Last updated: 14 February 2019
Due to state amendments, the residential code is not quite equivalent to the 2012. Still, major improvement to the new energy code include:

More efficient windows (U-0.32);
More efficient crawlspace walls;

Mandatory whole-house blower-door test requirement, beginning 2016;
More stringent heating duct leakage testing;
Whole-house mechanical ventilation;
More efficient lighting (75 percent high efficiency fixtures and lights)

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