After the IECC is published, the Department of Energy (DOE) is required by the Energy Conservation and Production Act (ECPA) to review the newly published edition of the code and to issue a determination as to whether the updated edition improves the energy efficiency of commercial and residential buildings, respectively. The DOE uses Pacific Northwest National Laboratory (PNNL) for this work and is allowed 12 months to conduct its review and publish its determination in the Federal Register. ECPA also requires states to review and/or update their energy codes following the publication of a positive determination. Interestingly, there are seven states that currently do not have a statewide energy code, so they must be simply reviewing the DOE determination and moving on. See the most current energy code adoption status by state.

What is the reality? Speaking only from a residential code perspective, the determination uses a combination of qualitative and quantitative analysis to identify changes that have a direct impact on residential energy efficiency of homes. The qualitative assessment looks at all code changes approved by the ICC for inclusion in the 2024 IECC. Individual changes are characterized to identify those expected to impact energy efficiency in a significant portion of typical residential buildings across the climate zones in the United States. The quantitative analysis uses an energy model and DOE prototype homes that are simplistic in form—basically, a simple rectangle over a slab on grade, crawlspace, basement, and one and two stories. The results of the analyzed estimate combined effects of aggregated and weighted results across the range of climates, building types, and foundation types to quantify the national average savings impacts of the updated code.…