2021 International Energy Conservation Code Published After Multiple Appeals

Following a three-year development process, the 2021 ICC family of model building codes has been published. Numerous changes to the International Energy Conservation Code (IECC) are of particular interest to home builders this year.

The development of the 2021 IECC was marked by controversy, culminating in multiple appeals by NAHB and others. Two of NAHB’s appeals were upheld by the ICC Board.

In the end, several problematic code changes that had been twice disapproved (first by the code development committee and then at public comment hearings) got into the 2021 IECC as a result of a controversial online ballot heavily influenced by block voting from non-code enforcement government officials that was linked to a single voting guide. Many of these proposals are not cost effective for home owners and will negatively impact housing affordability with little energy savings benefit. It will take several decades to achieve a simple payback on the initial investment under some of the new measures. NAHB is developing a Code Adoption Kit for the 2021 IECC residential requirements and other 2021 I-Codes that will be available in the Spring of 2021. The purpose of the toolkit is to help jurisdictions make informed decisions on adoption of the new model codes based on the substance of the changes.

Significant changes to the 2021 IECC residential requirements include:

• Increased prescriptive attic insulation: R49 in Climate Zones 2-3 and R60 in Climate Zones 4-8.
• Increased prescriptive above-grade wall insulation: R20+5 or R13+10 in Climate Zones 4 and 5.
• Increased prescriptive slab insulation: 2 feet at R10 in Climate Zone 3, and 4 feet at R10 in Climate Zones 4 and 5.
• Ducts in conditioned space will have to be tested for tightness in all new dwellings.
• Dimmers, occupant sensor controls, or other controls will be required for most lighting fixtures.
• On top of compliance with the base energy code, the new provisions will require that an additional packaged solution be superimposed from a pre-defined list of measures: (1) insulation and glazing, (2) heating and cooling, (3) water heating, (4) ducts entirely within conditioned space, or (5) air sealing and ventilation. Alternatively, an additional 5% improvement must be shown via a performance compliance path or the Energy Rating Index (ERI).
• For the ERI compliance path, the maximum ERI thresholds are lowered by 5-8 points (9-13% increase in stringency) depending on the climate zone and the amount of credits available for onsite renewable energy has been limited to 5% or less of energy use.
• An adoptable Residential Zero Energy Appendix would require even further increases to energy efficiency requirements coupled with significant amount of onsite generation, if adopted as minimum code. These types of provisions must remain in the above-code, voluntary market and be incentivized.

Like other ICC “model” codes, the IECC is designed to be amended by state or local jurisdictions to account for local considerations, such as geography, climate and local practices. The process for adoption of new building codes varies between jurisdictions based on schedule, governing bodies involved, and the degree to which the provisions are amended. The NAHB Code Adoption Toolkit will serve as a resource for HBAs during evaluation of the 2021 model codes. The toolkit will include lists of significant changes, estimated cost impacts of those changes (where available), and suggested amendments. Please contact Vladimir Kochkin with any questions regarding the 2021 IECC and the Residential Energy Code Adoption Kit. For questions about other ICC codes, please contact NAHB Codes and Standards staff.