Top 4 2021 IECC-R Proposals to Track

Of the hundreds of proposed changes to the 2021 building codes, these four IECC proposals are the ones to watch.

The Group B code hearings were held in Albuquerque, N.M., between April 28 and May 8. While there were a number of codes considered during this 11-day stretch, the IECC-R is arguably the “star” of this set of codes. There were hundreds of code change proposals filed; some familiar, some new. Rather than recite all that transpired over the six days that the IECC-R was heard, we’re going to highlight the outcomes* of a few
significant proposals.


Proposal: This would create a new compliance alternative in Section R407. Compliance would be determined using heating and cooling load analysis. (See table below.) Energy code compliance through this path would still need to meet the provisions identified in Sections R102.3, R403.5, R403.8, R403.9, R403.10, R403.11, and R404.1.

Equivalent HVAC building load. The ratio of the space cooling load and space heating load to conditioned floor area shall be less than or equal to the values in Table R407.3.

Air leakage and duct leakage testing would be retained in this proposed compliance path.

Committee Action: Approved as Modified – “This is a clean simple compliance path, it increases flexibility by adding another option, focuses not on materials but efficiency. The modifications clarified that the language applies to envelope load and it does not impact equipment efficiencies or lighting, corrected the citation, and added as mandatory the certificate (Vote: 6-5).”

Commentary: Interestingly, there was an assembly motion to disapprove this proposal. However, the online vote after the hearing did not sustain that motion by a 61%-39% margin, so it remains approved as modified. This will be a proposal that will certainly garner a number of comments this summer, and will generate quite a bit of testimony in October.


Proposal: This proposal would create a new compliance option for wood frame wall insulation requirements. (Underlined content = proposed new language)

h. The first value is cavity insulation, the second value is continuous insulation. Therefore, as an example, “13+5” means R-13 cavity insulation plus R-5 continuous insulation.

This proposal looks to accomplish a few things:

  • Include an additional equivalent insulation option for cavity insulation, because in the 2018 IECC, an equivalent cavity insulation-only option is missing in Climate Zones 6-8;
  • Provide for equivalent continuous insulation-only options which are also are missing;
  • Provide the table with a simple yet complete set of insulation options for location of insulation on wood frame wall assemblies for each climate zone, which would improve the usefulness of prescriptive options and show the full range of equivalent insulation options (e.g., cavity only, hybrid cavity + continuous, and continuous only);
  • Address concerns that the prescriptive table favors certain options over others by excluding viable options in some climate zones;
  • Provide more flexibility to coordinate insulation options with vapor retarder provisions in the building code, which vary by climate as well as insulation strategy. The proposed flexibility gives users more choice between insulation options that provide equivalent assembly U-factor (as a minimum requirement of the energy code), yet have different capabilities and functions with respect to comfort, air-tightness, moisture control, thermal bridging mitigation, and other factors that are important to an overall code-compliant wall assembly.

The reason statement for this proposal also contains a number of calculation spreadsheets for the different insulation levels/respective climate zones.

Committee Action: Approved as Submitted – “This provides additional options for compliance. It simplifies code language and encourages users to look at all the associated issues (Vote: 8-3).”

Commentary: If for no other reason than the 8-3 committee vote, this will probably have comments filed. However, it seems to have positive momentum heading into October’s hearing.

RE223-19 (Appendix RB)

Proposal: This proposal would create a new appendix for zero energy residential buildings. This section, if adopted, would require the rated design to have a score less than or equal to the values in Table RB103.2 when compared to the ERI reference design determined in accordance with RESNET/ICC301 for ERI values that both include and do not include onsite power production.

a. The building shall meet the mandatory requirements of Section R406.2, and the building thermal envelope shall be greater than or equal to the levels of efficiency and SHGC in Table R402.1.2 or Table R402.1.4 of the 2015 International Energy Conservation Code.

The footnote in this table creates a prescriptive backstop of the 2015 IECC, which already exists in section R406 of the 2018 IECC. While the ERI numbers are notably lower than those in the body of the code, this is a zero-energy appendix.

(Quick note on appendices: They are sections of building code language typically confined to a specific topic. Since these sections are not in the body of the model code, they are considered optional content that jurisdictions can choose to adopt if it is applicable. An example would be the appendix on tiny homes. Some jurisdictions have seen a rise in tiny home construction, so they have adopted that appendix to provide the local building community with code guidance. Other jurisdictions have not felt the need to adopt the tiny home appendix yet.)

Committee Action: Disapproved – “It needs additional compliance language for buildings without solar. Does not offer guidance or flexibility, it needs the term “net” included in title, and the ERI numbers are too low (Vote: 6-5).”

Commentary: Because of the near-split decision, as well as the guidance provided by the committee, this will likely have a handful of comments filed against it. It wouldn’t be surprising to see this proposal, or something like it, being added to either the 2021 or the 2024 IECC. With so many cities and states committing to 100% renewable energy goals by 2030, 2040 or 2050, the ICC will need to provide a tool for their members (code officials) in those respective jurisdictions, preferably sooner rather than later.

In the reason statement, it is stated that this appendix’s guidance would result in a residential building that has zero energy consumption over the course of a year. That’s a little deceptive, because while that would most likely be true in years 1 and 2, as the onsite power production system (probably PV) degrades over time (approximately 1% loss in productivity per year), the building will no longer be zero energy. It will still have a very small utility bill, but after 10 years, it will go from a zero-energy building to a ~10% energy building.

RE224-19 (Parts I & II; Appendix RB and U)

Proposal (Part I): This proposal is attempting to add stretch code provisions to the appendix of the IECC. To accomplish this, residential buildings or portions of residential buildings would need to look to the requirements of ASHRAE/IES Standard 90.2.

Committee Action (Part 1): Disapproved – “If it is in an appendix, it takes a specific action by a jurisdiction. If it is an alternative path, it belongs there. Unclear if mandatory requirements are included. There is an unconfirmed potential conflict with the 2018 IECC and the potential unconfirmed comments on the 90.2. (Vote: 7-4).”

Proposal (Part II): This proposal is attempting to add stretch code provisions to the appendix of the IRC. Since many of the provisions within the IECC-R and IRC Chapter 11 are consistent/overlapping, it is usually prudent for a code change proposal of this magnitude to cover both documents.

It was also noted in the reason statement that a stretch code that references ANSI/ASHRAE/IES Standard 90.2-2018 allows for a stretch code that is based on an ERI methodology compatible with the ERI pathway within the base IECC.

Committee Action (Part II): Disapproved – “Keeping in alignment with the decision for Part 1. If it is in an appendix, it takes a specific action by a jurisdiction. If it’s an alternative path, it belongs there. Unclear if mandatory requirements included. There is an unconfirmed potential conflict with the 2018 IECC and the potential unconfirmed comments on the 90.2. (Vote: 7-4).”

Commentary: There are many ways to structure a stretch code. This was merely one approach. While rejected by the committee, the talented and intelligent people who work on codes will probably come up with a suitable alternative either this summer or during the next code development cycle.

The committee action on Part II is simply staying consistent with their action on Part I.


*In the context of this article, outcome means the decision of the code committee. This is the first stage in a 3-stage process. After the code committee makes their recommendation, the code change proposals and their respective recommendations are put out for public comment. Those comments will then be considered at a public comment hearing (PCH) in Clark County (Las Vegas), NV on October 23-30, 2019. Per the ICC: “Following the PCH, the Online Governmental Consensus Voting (OGCV) period will start approximately 2 weeks after the conclusion of the PCH. The results of the PCH will be combined with the OGCV to determine the final disposition of the code change proposals that were considered at the PCH.”