Seven years ago, Georgia led the nation. Yep. We were the first state to adopt an energy code that made blower door testing mandatory. All new homes built in the state had to show through performance testing that they had an air leakage rate of less than 7 air changes per hour at 50 Pascals of pressure difference (ach50).
When I wrote about it in 2010, I called our new code “groundbreaking.” Since then, we’ve been passed many times by other states. Now we’re finally updating the energy code here, and it’s been a struggle to move that threshold from 7 ach50 to something lower. And the reason has nothing to do with the difficulty of air sealing.
In 2010, Georgia adopted the 2009 International Energy Conservation Code (IECC) with amendments and supplements. The 2009 IECC didn’t actually have blower door testing as a mandatory requirement. That was a Georgia thing. At that time, the state also started requiring duct leakage testing and R-5 insulation for attic hatches. And we banned powered attic ventilators (except solar) and electric resistance heat used as a primary heat source.
In 2014, Georgia adopted the 2012 International Residential Code (IRC). One requirement in the mechanical section is that mechanical ventilation be installed if a house comes in more airtight than 5 ach50.
Now, in 2017, the Georgia Department of Community Affairs has been holding meetings to update to the 2015 IECC. We usually do every other code cycle, so we skipped over the 2012 version. The air leakage requirements in the 2015 IECC are in section R402.4.1.2 and stated thus:
The building or dwelling unit shall be tested and verified as having an air leakage rate not exceeding five air changes per hour in Climate Zones 1 and 2, and three air changes per hour in Climate Zones 3 through 8.
In the 2015 version, testing is now…