New Building Energy Codes 2026: What Homeowners Need to Know
How Building Energy Codes Work
The International Energy Conservation Code (IECC) is a model code published every three years. States choose whether and when to adopt each edition, sometimes with modifications. Once adopted by a state, local jurisdictions may further amend or apply stricter local codes. When you pull a permit for new construction, an addition, or sometimes a major renovation, you must comply with the code in effect in your jurisdiction at permit issuance.
This matters for energy efficiency in specific ways: it determines minimum insulation requirements, window performance specs, HVAC efficiency ratings, and in some jurisdictions, fuel source restrictions. Understanding what code applies in your area before starting a project can prevent expensive mid-construction changes.
2021 IECC: What Changed from Previous Editions
The 2021 IECC introduced several significant changes over the 2018 edition that are now taking effect as states complete adoption:
- Air sealing requirement: Maximum 3 ACH50 for new construction (versus 5 ACH50 in the 2018 IECC), requiring more rigorous air sealing measures and mandatory blower door testing
- Fenestration requirements: More stringent U-factor and SHGC requirements for windows, especially in northern climate zones
- Duct sealing: Mandatory duct leakage testing (previously just recommended in some zones)
- Efficient HVAC minimums: Higher minimum SEER2 ratings for central air conditioners
- EV-ready infrastructure: New residential buildings must include conduit for EV charging in most climate zones
- Solar-ready construction: Conduit from roof to electrical panel for future solar installation
For homeowners building additions or doing major renovations, these requirements apply to the permitted work. A new master bedroom addition must meet 2021 IECC standards even if the existing house was built to 2006 IECC standards.
State Code Adoption Status (2026)
| State | Current Code | Notable Local Amendments |
|---|---|---|
| California | Title 24 (2022 edition) | Solar required on new homes; solar-ready on additions |
| New York | 2020 ECCC (based on 2018 IECC + stretch) | Municipal stretch code allows fuel restrictions |
| Massachusetts | 9th Edition (based on 2021 IECC) | Stretch code allows all-electric requirements |
| Colorado | 2021 IECC | Some jurisdictions require electric-ready construction |
| Washington | 2021 WSEC (based on 2021 IECC) | All-electric required in some counties |
| Oregon | 2021 ORSC | Enhanced EV charging requirements |
| Texas | 2009 IECC | Limited statewide code; varies by municipality |
| Florida | 7th Edition (based on 2018 IECC) | Hurricane resistance requirements overlay energy code |
Texas and Florida lag significantly in code adoption, meaning construction in those states still meets minimum requirements that are 10+ years old by national standards. This has real consequences: new homes in Texas built to 2009 IECC often qualify as energy efficiency "improvements" under HOMES programs because they're so far below current best practice.
All-Electric Requirements in Local Jurisdictions
Several California cities enacted building ordinances requiring all-electric new construction starting in 2020–2023: San Jose, San Francisco, Menlo Park, Berkeley, and over 70 other California municipalities. New York City passed Local Law 154 requiring all-electric construction in buildings under 7 stories from 2024 onward, and larger buildings from 2027. Seattle's building code effectively requires heat pumps for most new construction.
These local fuel restriction ordinances have faced legal challenges, and a federal appeals court initially ruled against Berkeley's ordinance before a subsequent ruling. The legal landscape is still evolving. Before designing a new home with gas appliances in a major metro area, verify your specific municipality's current requirements.
For state-by-state rebate programs that complement these code requirements, see California energy rebates, Washington state programs, and Oregon rebate programs.
What Code Changes Mean for Renovation Projects
Major renovations trigger code compliance for the permitted work. The practical implications:
HVAC Replacement
Replacing an HVAC system typically requires a permit in most jurisdictions. The new system must meet current minimum efficiency standards — SEER2 14.3 minimum for central AC in most of the US (SEER2 15.2 in the Southeast and Southwest). This requirement applies even if you're replacing like-for-like equipment.
If you're already replacing HVAC for code compliance, installing a heat pump instead of a gas furnace replacement may cost a similar amount after rebates — and you avoid replacing the same system again in 5–10 years as gas appliance policies tighten further. Use the heat pump comparison calculator to evaluate the cost difference in your situation.
Window Replacement
Replacing windows with a permit requires meeting current ENERGY STAR requirements for your climate zone. Non-ENERGY STAR windows typically don't qualify for state rebate programs either, making compliance economically rational as well as legally required. The window rebate guide covers current ENERGY STAR requirements by climate zone.
Additions
A room addition must meet 2021 IECC (or current local code) requirements for insulation, air sealing, and fenestration. The existing house is typically exempt — you're not required to bring the existing structure up to code, only the permitted addition. However, if you extend your HVAC system to serve the addition, the HVAC work triggers minimum equipment efficiency requirements.
Code Compliance vs. Rebate Eligibility
An important distinction: meeting code minimum doesn't make you eligible for HOMES or HEAR rebates. Rebate programs require achieving 20–35% better performance than code minimum for HOMES, and specific equipment efficiency tiers for HEAR. Building to code is the floor; rebate eligibility is a higher bar.
In states with older codes (Texas, Florida, South Carolina), it's possible to build to local code and still qualify for HOMES rebates because the code baseline is so low. In California, building to Title 24 is already relatively demanding — exceeding the rebate threshold requires additional investment beyond code requirements.
The Energy Code and Insurance
An emerging issue: insurance companies are increasingly reviewing building codes in underwriting decisions for wildfire-prone, flood-prone, and hurricane-prone areas. Homes in high-risk areas built to outdated codes are increasingly difficult to insure. While energy codes and insurance are separate regulatory domains, the trend toward code adoption and enforcement is partly driven by insurance market pressure — particularly in California and Florida.
Finding Your Jurisdiction's Current Code
The Department of Energy's Building Energy Codes Program website (energycodes.gov) maintains a state-by-state code adoption database, though it sometimes lags actual adoptions by several months. Contact your local building department directly to confirm which code edition applies to your permit application. Ask specifically: "Which edition of the International Energy Conservation Code is currently in effect for new residential construction?" and "Are there any local amendments?" Getting this wrong can mean failing inspections or expensive mid-project changes.
Permit Implications for DIY Energy Work
Homeowners sometimes skip permits to avoid code compliance requirements. This is a significant mistake for energy improvements. Unpermitted HVAC work can void manufacturer warranties. Unpermitted electrical work creates liability and insurance problems. Most critically for rebate purposes: work done without permits may be ineligible for HOMES and HEAR rebates because program administrators often require permit documentation as proof that installation met code standards.
The benefit of pulling permits — beyond legal compliance — is that the inspection process provides an independent check on installation quality. An HVAC inspector who finds a heat pump installed with inadequate refrigerant charge, incorrect electrical service, or a failed condensate drain catches problems you'd otherwise discover only when the system fails prematurely. For major investments in heat pumps and insulation, the permit cost ($100–$400 typically) is worthwhile protection. Check your state's current code requirements at Oregon, Washington, or your specific state's rebate program page for current compliance information.