The Minnesota Department of Labor and Industry (DLI) has completed the process to update the statewide building energy code for residential buildings. The new code is based on the 2012 International Energy Conservation Code (IECC), with some modifications listed below.
MEEA has analyzed the economic potential of adopting the 2012 IECC, with the Minnesota-specific modifications. We have found that a newly constructed 2,400 square foot home in Minneapolis will use an average of 1,300 fewer kWh and 550 fewer therms per year if built to the 2012 IECC, as modified in Minnesota, compared to the current energy code. This would result in the average homeowner saving around $540 annually in utility bills. It is important to note that these energy and cost savings will continue for the life of a building, which can be 50 – 100 years or more. The United States Department of Energy has also done an analysis with similar findings and concluded that a homeowner with a 30 year mortgage will realize a positive cash flow in the first year, after considering initial construction costs and annual utility bill savings.
In addition to yielding economic benefits to homeowners, the proposed energy code will result in higher quality, healthier, and more comfortable buildings. In particular, the requirement for buildings to have air tight enclosures and well-sealed duct systems, verified with diagnostic tests, will help realize these benefits to air quality. A building enclosure that is tightly sealed, combined with a proper ventilation system, will prevent unwanted movement of air into and out of the building. This reduces the load on space heating and cooling equipment and increases the indoor air quality of buildings.
Other efficiency improvements that are included in the proposed energy code are higher efficiency windows and added basement insulation. Importantly, all of these measures and their energy efficiency improvements are most easily incorporated during the design and initial construction phase. It can be cost prohibitive to improve these measures in existing buildings, which is why it is crucial for these measures to be addressed in the building codes that regulate new construction.
Using the average number of one and two family residences built annually over the previous ten years in Minnesota (14,956 homes), multiplied by the potential annual energy savings per home in Minneapolis (59 MMBTU), there would be an annual statewide energy savings of over 880,000 MMBTU from building to the new 2012 energy code for residential buildings. That is equivalent to the amount of energy used by almost 4,000 homes, and utility bill savings would be over $8 Million annually for homeowners.
In 2012, the Department of Labor and Industry convened a stakeholder working group to address the issue of updating the statewide energy code. MEEA participated in this process, along with many organizations in Minnesota’s construction industry. Homebuilders, manufacturers, energy experts, building officials, and utility companies were some of the groups that participated and offered input on how to update Minnesota’s statewide building energy code. The group eventually sent recommendations on what the new code should look like in order to yield the most cost-effective benefits in the form of energy and utility bill savings for Minnesota’s building owners and operators. The code that was adopted by the Department of Labor and Industry in April, 2014 was largely a result of this process.
Below are the modifications Minnesota made to the model version of the residential 2012 IECC:
1. Wall Insulation (prescriptive table only):
- – Climate zone 6: R-20 or R-13 + 5
- – Climate zone 7: R-21
2. Basement Insulation:
- – R-15 continuous, with minimum R-10 exterior
- – Additional requirements for walk-out basements
- – R-10 continuous exterior insulation if tested air leakage rate < 2.6 ACH50
3. Duct Insulation: Vapor retarder required for unconditioned spaces
4. Specific requirements for basement moisture mitigation
5. Specific ventilation requirements (only allows balanced)
While the public comment period is over, there are still several procedural steps that must be completed to finalize the administrative rulemaking process. DLI will be submitting the code to the Office of Administrative Hearings (OAH), where it will be reviewed for a determination of reasonableness. After that, the Governor’s office will be able to review the code, with a chance to veto. Once those steps are completed, the code will be published in the state register and become effective 180 days later.