I-2066 and Washington’s Energy Code Status

What the court decided

In a 6-3 decision in Climate Solutions v. State of Washington (No. 104240-0), the court found that I-2066 combined four constitutionally distinct subjects — natural gas access, local air-quality authority, statewide building and energy codes, and an amendment to the Decarbonization Act — contrary to the single-subject rule in article II, section 19 of the state constitution. Because those subjects could not be severed, the initiative fell in its entirety. The decision affirms a 2025 King County Superior Court ruling. Three justices dissented and would have upheld most of the measure.

The Washington Supreme Court is the final authority on a question of state constitutional law, so this case is over. Changes to how the energy code treats fuel type would now have to come from the Legislature or from State Building Code Council rulemaking, not from this lawsuit.

What this changes for your project: nothing

The 2021 WSEC-R stayed enforceable throughout the litigation, and the State Building Code Council said so directly: the current 2021 codes remain in place until the Council adopts changes. Nothing in the ruling amends WAC 51-11R. As of the date below, the code text reads exactly as it did the day before the ruling:

• Credit totals are unchanged. Small 5.0, Medium 8.0, Large 9.0, Group R-2 6.5, and 2.0 for additions of 150 to 500 square feet (R406.3, WAC 51-11R-40620).
• Fuel normalization credits are unchanged. Combustion heating 0, heat pump with combustion or electric-resistance backup 1.5, electric resistance 0.5, heat pump 3.0, electric resistance with an inverter-driven ductless mini-split 2.0 (Table R406.2, WAC 51-11R-40610).
• Compliance paths, envelope requirements, and fenestration values are unchanged.

Permits in review, plans already submitted, and credit selections you have made all stand. No jurisdiction has been directed to stop enforcing the current code.

What is actually coming next

The change that will affect your projects is the 2024 edition of the energy code, which has been moving through rulemaking on its own track the whole time. The Council filed its proposed rule (CR-102) for the residential provisions on July 1, 2026 and set September 25, 2026 as the date of intended adoption. The effective date stated in that proposal and on the Council’s site is May 3, 2027. Until then, projects permit under the 2021 WSEC-R.

What to do now

• Proceed with the current code. The 2021 WSEC-R is the law today and will be the code your permit is reviewed against.
• Verify with your local AHJ. Your Authority Having Jurisdiction is the final word on what it requires. Some jurisdictions posted their own I-2066 guidance during the litigation and may refresh it now.
• Heat pumps still carry the most credit. System Type 4 earns 3.0 credits, unchanged by the ruling. A gas furnace is still permittable; it simply earns 0 from Table R406.2, so the credits have to come from R406.3.

Frequently Asked Questions

I designed around a gas furnace. Am I affected?

No. Gas heating was not prohibited by the 2021 WSEC-R before the ruling and is not prohibited now. Combustion heating earns 0 fuel normalization credits under Table R406.2, exactly as it did before, and the rest of your credits come from R406.3. Adding a heat pump alongside the furnace earns 1.5 under System Type 2.

Should I wait to pull my permit?

No. The pending-ruling reason to wait is gone, and the next code edition is not effective until May 2027. Waiting adds cost with nothing to gain.

Do the credit values in wsec.ai change?

No. This tool calculates against the enforceable 2021 WSEC-R text, which the ruling did not touch. wsec.ai will be updated when the Council adopts the 2024 edition, ahead of its effective date.