NAHB Publishes 2021 IECC Residential Code Adoption Kit

NAHB has published a code adoption kit for the 2021 International Energy Conservation Code (IECC). The purpose of the kit is to help jurisdictions make informed decisions on adoption of the new 2021 IECC residential model energy code, which contains many significant and detrimental changes after a fraught development process. The 2021 ICC family of model building codes was released earlier this year and is now available to jurisdictions for review and adoption. The development of the 2021 IECC was marked by controversy as a result of a disputed online ballot heavily influenced by block voting from non-code enforcement government officials that was linked to a single voting guide. In the end, several problematic code changes got into the 2021 IECC. An analysis published by Home Innovation Research Labs clearly establishes that many of these changes are not cost effective for home owners and will negatively impact housing affordability with negligible energy savings benefit. As an example, the new requirement for added attic insulation in climate zone 2 (R49 vs. previous R38) will save the owner of a 2,600 sq. ft. house about 67 cents per month on average (5kWh per month). Yet the cost to the consumer for the added insulation is over $1,000, making the simple payback period for the added insulation over 100 years. Simple paybacks for new insulation requirements are summarized in the table below. Cost-effectiveness metrics for other changes can be found in the Home Innovation report.

	Simple Payback, Years
	CZ 2	CZ 3	CZ 4	CZ 5	CZ 6	CZ 7
	Phoenix	Memphis	Baltimore	Chicago	Helena	Duluth
2021 IECC ceiling insulation	177	122	152	118	105	90
2021 IECC slab insulation		23	28	28
2021 IECC wall continuous insulation			103	78

In addition, many of these changes result in negative monthly cash flow for the home owner (i.e., the combined total for the mortgage and energy bill is higher) and a negative net present value (a metric sometimes used by economists to evaluate a life-cycle benefit of an investment). NAHB's code adoption kit for the 2021 IECC residential requirements covers a wide range of issues in the new code, including:

• List of significant changes to 2021 IECC residential provisions
• Amendments to 2021 IECC supported with substantiating information and cost-effectiveness data where applicable
• Cost-effectiveness evaluation of the 2021 IECC code changes including analysis of energy savings and construction costs conducted by Home Innovation
• A summary table with the status of state adoptions of the IECC around the country

Like other ICC "model" codes, the IECC is designed to be amended by jurisdictions to account for local considerations, such as geography, climate and regional 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 kit will serve as a resource for HBAs and other stakeholders as they evaluate the 2021 model codes. For more information on the 2021 IECC, please contact Vladimir Kochkin.