The dates
| Step | Date | Source |
|---|---|---|
| 2021 Washington State Energy Code in force (the code this replaces) | Since 15 March 2024 | SBCC Energy Code |
| Residential energy code proposal (CR-102) filed | 1 July 2026 | SBCC |
| Public hearings | 5 August 2026 (Olympia), 7 August 2026 (Spokane) | CR-102 |
| Written comments closed | 7 August 2026 | CR-102 |
| Final adoption, targeted | 20 November 2026 | SBCC |
| Effective statewide | 3 May 2027 | SBCC, CR-102 |
What the proposal changes for homes
From the CR-102 summary of the 2024 Washington State Energy Code, Residential (SBCC) and the council's June 2026 cost study (pCBA):
| Item | Proposed for 2024 WSEC-R | Who it touches |
|---|---|---|
| Window U-factor | 0.27 (from 0.28 in climate zone 5 and marine 4C, per proposal 24-RE-036) | New homes and additions |
| Air leakage | 3.0 air changes an hour; units under 800 sq ft stay at 4.0 | New homes |
| Ventilation | Heat or energy recovery ventilation required in climate zone 5 | New homes in climate zone 5 |
| Ducts | Generally in conditioned space or deeply buried | New homes and additions |
| Gas equipment | Electric-readiness measures when the home uses fuel gas or liquid fuel equipment | New homes with gas |
| AC replacement | Alterations rule encouraging heat pumps when an air conditioner is replaced (proposal 24-RE-019, section R503.1.2.5): heat pump path or duct/insulation path | Existing homes |
| Compliance | New Energy Rating Index path; energy credit table revised | Builders |
| Low-slope roofs | Cool-roof requirement | New homes with flat roofs |
The council says some sections present alternative options on which it requested testimony, so the adopted text may differ from this table. The cost study found the AC-replacement proposal "cost-effective under current WA utility rates" and called the two-path structure flexible.
What it means for a project in 2027
- AC replacements after 3 May 2027. If the final rule keeps the heat pump path, a straight AC swap may need duct or insulation work instead. Ask the contractor which path the quote follows. Seattle splits its HVAC permits into Heat Pump & AC and Furnace & Heating, so you can see who files which.
- New homes and additions. Plans drawn to the 2021 code before May 2027 should be checked against the date your department will apply the 2024 code.
- Timing. If you are close to the line, ask the building department how it treats an application in review on 3 May 2027. The state rule sets the effective date; it does not answer that question.
Permits in the three Washington cities we cover
| City | Heat pump / HVAC permits | Firms | Usual days to final | New-home permits |
|---|---|---|---|---|
| Seattle (Heat Pump & AC) | 15,441 | 272 | 105 | — |
| Seattle (Furnace & Heating) | 18,668 | 316 | 66 | — |
| Bellevue (HVAC & Mechanical) | 5,650 | 570 | 76 | 194 |
| Bellingham (HVAC & Mechanical) | 2,581 | 68 | 24 | 449 |
Seattle's new homes are not split out as a trade in our data, hence the dashes. Counts cover October 2023 to September 2026. For the permit itself, see the Seattle heat pump permit guide.
Check it yourself in five minutes
Open the council's Energy Code page after 20 November 2026 to see whether the residential code was adopted as proposed. Then, on the compare page for your city, sort heat pump installers by permits reaching final.
What this page does not cover
The table lists proposed changes, not adopted text. Cities can adopt local amendments, and we have not checked any city's. Our permit data does not tell us which code a permit was reviewed under.
How we know this
Dates and proposed changes are quoted from the Washington State Building Code Council's home page, its CR-102 filing for the 2024 residential energy code (1 July 2026) and its June 2026 preliminary cost-benefit analysis, read 26 October 2026. Permit counts are from the City of Seattle, City of Bellevue and City of Bellingham open permit data, October 2023 to September 2026; days run from issue to final.
Numbers come from City of Seattle (SDCI) building, trade and electrical permits on single-family and duplex homes (the city's open-data exports); City of Bellevue permits on single-family homes and condo units; City of Bellingham permits on single-family homes, duplexes and townhomes, data through October 17, 2026. Nobody paid to be on this page and nobody can.
See every Seattle heat pump installer by permit record →
Questions
- When do Washington's 2024 codes take effect?
The State Building Code Council says "The effective date of the 2024 codes will be May 3, 2027." The residential energy code rule filed on 1 July 2026 uses the same date for all counties and cities.
- Is the 2024 Washington residential energy code final?
Not as of 26 October 2026. The council took comments to 7 August 2026, held hearings on 5 and 7 August, and lists final adoption as targeted for 20 November 2026. The changes below are from the proposed rule.
- Will I have to install a heat pump when I replace my AC?
The proposal adds an alterations rule for AC replacement with two paths: a heat pump, or a duct and insulation path. The council's cost study found it cost-effective at current Washington utility rates. The final text is due with adoption.
- How many heat pump and AC permits does Seattle issue?
Seattle issued 15,441 Heat Pump & AC permits from October 2023 to September 2026, to 272 firms. The usual filed job value was $8,000.
- Does a permit filed before 3 May 2027 use the old code?
The rule sets the date the new code becomes effective; how a department treats an application already under review on that date is up to the department. Ask yours when you apply.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
Related guides
- Bellingham building permit search: eTRAKiT, the permit dashboard and public records
- Arlington, VA building permit search: Permit Arlington lookups and FOIA requests
- Arlington, VA contractor license lookup: DPOR class and specialty, the County permit search, and what the permits show
- Austin contractor license lookup: which license, where to search, and what the permits show
- Do I need an HVAC permit in Bellingham? Yes: the mechanical permit, its fees, and the electrical side
- Do I need a permit for a heat pump in Seattle? Yes: a refrigeration permit only a licensed contractor can pull, and a 45 dB noise limit
For one city
- Washington State Building Code Council (home page) (accessed 2026-10-26)
- CR-102 Proposed Rule Making, 2024 Washington State Energy Code, Residential (filed 1 July 2026) — SBCC (accessed 2026-10-26)
- 2024 Washington State Energy Code, Residential Provisions: preliminary cost-benefit analysis (June 2026) — SBCC (accessed 2026-10-26)
- Energy Code — Washington State Building Code Council (accessed 2026-10-26)