In Minnesota, the Department of Labor and Industry (DLI) administers the state’s building code, which describes minimum requirements that must be followed for new construction and building renovations. For the residential energy code, DLI has proposed adopting a slightly amended version of the International Energy Conservation Code’s (IECC) most recent version—the IECC 2012.
While not quite as efficient as the full, unamended IECC 2012, the DLI’s proposed code is less cost prohibitive, and is at least 20 percent more efficient than Minnesota’s current code (roughly equivalent to the IECC 2006). The draft code will likely be released for public comment in August or September.
In the meantime, the U.S. Department of Energy has released a report that outlines the construction costs and energy savings for Minnesota residential builders to move to the IECC 2012.
One notable change is that the IECC 2012 requires a maximum air infiltration rate of 3ACH(50) for new homes. This means that in order to meet code, a house pressurized to 50 pascals (approximately the pressure of a 20 mile-per-hour wind) should exchange a houseful of new air no more than three times in one hour. A lower air exchange rate means the house has is less leaky and more energy efficient. The IECC 2006 averages an air exchange rate of 7ACH(50). The Builders Association of Minnesota has claimed that many builders already construct tighter homes, so an air exchange rate of 1.7ACH(50) was used as a baseline in addition to 7ACH(50).
Below, you’ll see the energy savings and payback periods of the IECC 2012’s 3ACH(50) requirement compared to the air infiltration rates mentioned above.
The Minnesota Building Performance Association researched its own payback numbers using the proposed draft code. It concluded that even without considering air infiltration at all, the average payback statewide will be eight to nine years.
Regardless of the baseline used, the report shows that it won’t take long for homeowners to pay off the improvements. Even the slightly amended version of the IECC 2012 proposed by Minnesota’s DLI shows cost-effectiveness and great energy savings.