2026 Pennsylvania Energy Code Update: 2021 IECC Effective July 1
March 12, 2026In October of 2025, the Pennsylvania Independent Regulatory Review Commission (IRRC) updated Pennsylvania’s Uniform Construction Code (UCC) adopting the 2021 International Energy Conservation Code (IECC). The state adopted the model code with several amendments, retaining some prior modifications and declining to adopt certain new national provisions.
The update was officially approved on October 16, 2025, and became effective January 1, 2026. Any design or construction contract executed on or after January 1, 2026, or any permit application submitted on or after July 1, 2026, must comply with the updated UCC.
The adoption of the 2021 IECC series introduces significant updates across multiple areas of construction. For both residential and commercial projects, the changes impact structural design, mechanical systems, electrical work, and energy efficiency requirements.
The 2021 IECC brings a range of changes for both commercial and residential projects. Here are some of the most important to be aware of for energy code compliance.
PA 2021 Residential Energy Code Key Updates
- 2018 Insulation Table Retained – Pennsylvania did not adopt the updated 2021 IECC insulation table. As a result, projects will continue to use the 2018 insulation requirements for code compliance.
- No Additional Efficiency Package Requirement – The state did not adopt the 2021 IECC’s “additional efficiency” package options, preserving greater flexibility for builders.
- Alternative Pathways Offer More Flexible Envelope Leakage Targets – Under certain alternative compliance pathways, the allowable building envelope leakage is less stringent than under the standard prescriptive pathway, providing additional design flexibility.
PA 2021 Commercial Energy Code Key Updates
Pennsylvania adopted the 2021 IECC commercial provisions with targeted modifications, including:
- ERVs are Required – Under the prescriptive path (i.e. COMcheck) energy recovery ventilators are required for all dwelling units. Energy modeling offers more flexibility and enables avoiding ERV (Energy Recovery Ventilator) installation.
- Commissioning Requirements are Expanded – Commissioning requirements are more defined and stringent, making it more enforceable.
- All Code Pathways Have Increased Energy Efficiency– Under the prescriptive path, specifically building envelope and lighting components have become more efficient.
What the PA Energy Code Update Means for the Industry
Pennsylvania’s version of the 2021 IECC:
- Strengthens core efficiency standards
- Maintains strong inspection and documentation requirements
- Preserves flexibility in certain design areas
- Avoids some of the more aggressive national add-ons
For builders, developers, and design professionals, energy modeling, duct performance, and documentation remain central to compliance under the updated code.
If you have questions about how these updates impact your upcoming projects, our team is here to help. Contact us for guidance on navigating the new requirements in Pennsylvania and ensuring your projects remain fully compliant.