2024 IECC Code Change Proposal Synopsis
Below you will find summaries of the draft code amendments and links to revision details that were submitted by NBI into the ICC process to advance the 2024 IECC. They are identified as Commercial or Residential and categorized by efficiency, renewable energy, electrification, grid integration, existing buildings, or zero energy home. Each item provides a brief code change title, the section of the code that could be impacted in brackets, a proposal number, summary, and link to more detail.
Commercial Proposals Residential Proposals
Detailed code language and brief reason statements are also available in this printer-friendly document.
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The IECC Committee Action Reports (CAR) have been released, which includes a summary of the actions taken by the respective IECC Consensus Committee for each submitted code proposal. The voting process will begin soon, followed by the release of the full 2024 IECC monograph. Access the Residential document here and access the commercial document here, plus an update on four proposals.
Summaries of the Draft Code Amendments
Commercial
Efficiency
Air Barrier Testing [C402] CEPI-58-21 – APPROVED AS MODIFIED
Increase building size threshold for testing to 250,000 ft2 and reduce allowable air leakage rate to 0.25 cfm/ft2.
Horticultural Dehumidification [C403] CEPI-84-21 – APPROVED AS MODIFIED
Increases the efficiency of dehumidification systems in horticultural applications.
Horticultural Lighting[C405] CEPI-185-21 – APPROVED
Increases stringency for lighting in horticultural applications.
Energy Monitoring [C405] CEPI-138-21 – APPROVED AS MODIFIED
Reduces size threshold for energy monitoring requirement to 10k sqft to align with common benchmarking policies.
Energy Monitoring for EVs[C405] CEPI-140-21 – APPROVED AS MODIFIED
Requires submetering for EVs where installed.
Commissioning [C408] CEPI-215-21 – APPROVED
Reduces thresholds for required commissioning of systems.
Multifamily Alignment Multiple CEPI-53-21 – DISAPPROVED
Aligns requirements for multifamily buildings across commercial and residential provisions.
Cool Roof Expansion [C402] CEPI-50-21 – DISAPPROVED
Increases SRI requirement for Climate Zones 0-3 and establishes requirements for cool roofs in CZs 4 and 5.
Dedicated Outdoor Air Systems (DOAS) [C403] CEPI-98-21 – DISAPPROVED
Requires commercial buildings to install a DOAS system, separating ventilation from space conditioning.
Renewable Energy
Biomass [C202] CEPI-12-21 Part 1 – APPROVED AS MODIFIED
Clarifies the type of biomass that counts as a renewable energy resource.
Onsite Renewable Energy [C405] CECPI-2-21 (Originally CEPI-5-21) – APPROVED AS MODIFIED
Requires on-site renewable energy generation.
Renewables Definition Appendix CC CEPCI-5-21 (Originally CEPI-248-21) – APPROVED AS MODIFIED
Clarifies renewable energy terms in Appendix CC.
Energy Storage Ready CEPI-7-21 – APPROVED AS MODIFIED
Makes energy storage ready requirements mandatory for all buildings.
Electrification
Commercial Decarbonization [C402] CEPI-22-21 – DISAPPROVED
Requires all new construction be all-electric.
Grid Integration
Grid Integrated Thermostats [C403] CEPI-099-21 – APPROVED AS MODIFIED
Requires grid-integrated controls on space heating and cooling systems that adjust temperature within 4-degrees.
Grid Integrated Water Heating [C404] CEPI-125-21 – APPROVED AS MODIFIED
Requires grid-integrated controls on electric storage water heaters (37-120 gallons/ “residential style”).
Electric Vehicles [C405] CECPI-1-21 (Originally CEPI-146-21 Part I) – APPROVED AS MODIFIED
Requires EV charging for all commercial building types. Energy Storage Ready C405 Requires commercial and multifamily energy storage readiness.
Solar and Storage Inverters [C405] CEPI-142-21 – APPROVED AS MODIFIED
Requires solar and energy storage systems be equipped with smart inverters for grid-integrated controls.
Grid Optimal Credits [C406] CEPI-197-21 – WITHDRAWN
Establishes credits for buildings to shed load during peak demand hours.
Existing Buildings
Additional Efficiency Credits for Existing Buildings [C506] CEPI- 217-21 – APPROVED AS MODIFIED
This proposal adds a requirement that additions and large alterations achieve a minimum level of points from C406 through the addition of a new Section C506.
Acceptance Testing for Alterations [C503] CEPI-229-21 – APPROVED AS MODIFIED
Requires acceptance testing of existing HVAC, SHW or lighting systems that serve alterations.
HVAC Control Upgrade in Alterations [C503] CEPI-227-21 – APPROVED AS MODIFIED
New HVAC equipment in alterations must have controls that comply with current code requirements.
Duct Leakage Testing in Alterations [C502] [C503] CEPI-219-21 – APPROVED AS MODIFIED
Ducts must be tested when equipment is replaced.
System Sizing in Commercial Alterations [C503] CEPI-228-21 – APPROVED AS MODIFIED
New equipment installed in alterations has to be right sized based on the alteration.
Testing of Gas Piping in Alterations [C502] [C503] CEPI-218-21 Part I – DISAPPROVED
When new gas equipment is installed, the gas piping has to be leakage tested.
Lighting Control Upgrades in Alterations [C503] CEPI-231-21 – DISAPPROVED
New luminaires in alterations must have lighting controls that comply with current code requirements.
Residential
Efficiency
Multifamily Alignment [Multiple] – REPI-069-21 – APPROVED
Aligns requirements for multifamily buildings across commercial and residential provisions.
Efficiency Credits [R408] – REPI-018-21 – APPROVED AS MODIFIED
Changes residential option packages to a credit-based structure similar to Commercial C406.
Renewables
Biomass Waste Definition [R202] CEPI-12-21 Part 2 – WITHDRAWN
Adds definition of biomass waste and clarifies definition of renewable energy resources.
Solar Readiness [R404] – REPI-007-21 – APPROVED AS MODIFIED
Requires single- and two-family solar readiness. Requires multifamily to comply with a sister provision under commercial section of energy code.
Renewable Energy Credits [R404] REPI-158-21 – APPROVED AS MODIFIED
Clarifies RECS definition and documentation requirements for RECS. Electrification
Residential Decarbonization [R202] – REPI-017-21 – DISAPPROVED
Requires all new construction be all-electric.
Grid Integration
Grid Integrated Water Heating [R403] REPI-090-21 – APPROVED AS MODIFIED
Requires grid-integrated controls on electric storage water heaters (37-120 gallons/ “residential style”).
Grid Integrated Thermostats [R403] – CEPI-099-21 – APPROVED
Requires grid-integrated controls on space heating and cooling systems that adjust temperature within 4-degrees.
Solar and Storage Invertors [R404] – CEPI-142-21 – APPROVED
Requires solar and energy storage systems be equipped with smart inverters for grid-integrated controls.
Electric Vehicles [R404] CEPI-146-21 Part II – DISAPPROVED
Requires single- and two-family EV charging. Requires multifamily to comply with a sister provision under commercial section of energy code.
Energy Storage Readiness [R404] – CEPI-007-21 – APPROVED AS MODIFIED
Requires single- and two-family energy storage readiness.
Zero Energy Home
Zero Energy Home Appendix Update [Appendix RC] REPI-161-21 – APPROVED
Updates the Zero Energy Home Appendix with ERI targets based on a survey of Passive House scores
Zero Energy Home Appendix Decarbonization [Appendix RC] REPI-155-21 – APPROVED AS MODIFIED
Updates the Zero Energy Home Appendix to require all-electric construction.
Zero Energy Home Appendix Renewable Definitions [Appendix RC] REPI-161-21 – APPROVED
Clarifies renewable energy terminology used in the Zero Energy Home Appendix.
Existing Buildings
Additional Efficiency Packages for Existing Buildings [R506] REPI-144-21 – APPROVED AS MODIFIED
This proposal adds a requirement that large additions and large alterations include a package option from R408.
HVAC Control Upgrade in Alterations [R503] REPI-152-21 – APPROVED AS MODIFIED
New HVAC equipment in alterations must have controls that comply with current code requirements.
Duct Leakage Testing in Alterations [R502] [R503] REPI-145-21 – APPROVED AS MODIFIED
Ducts must be tested when equipment is replaced.
System Sizing in Residential Alterations [R503] REPI-151-21 – APPROVED
New equipment installed in alterations has to be right sized based on the alteration.
Testing of Gas Piping in Alterations [R502] [R503] CEPI-218-21 Part II – DISAPPROVED
When new gas equipment is installed, the gas piping has to be leakage tested.
Copyright © 2021 New Buildings Institute. Use of New Buildings Institute’s (NBI) Draft Amendments for the development of the 2024 IECC (published October 11, 2021) is permitted on a royalty-free basis. NBI claims no rights in and makes no representations as to the contents or use of the International Energy Conservation Code®. NBI makes no representations as to the suitability of this code language for any purpose, and all content is provided as-is. All other rights reserved.
Return to NBI’s web page on the 2024 IECC National Model Energy Code (Base Codes)