Washington's energy code, without the spreadsheet.
A wizard, a C3 alternative, and human plan review for the 2021 WSEC-R — built directly on the Washington Administrative Code.
Or get a human to help →Pricing
Tools you use yourself, or a real human to do it with you.
Tools — Do it yourself
Modern web version of the C3 worksheet. Same credit math, no macros, no Excel. Mac, mobile, or PC.
- Web-based — no install
- Account required to save
- Permit-ready PDF output
The full guided walkthrough plus your permit-ready compliance package.
- Guided wizard with live credit math
- AI chat for code questions
- Final compliance PDF
- Plan-set checklist
- Blower door + insulation + air leakage stickers
- Build Plan with subcontractor homework
One-time · no subscription
Upgrade from the C3 Calculator to the full Wizard + PDF for $80.
See what's included →Help — Get a human in the loop
Stuck on one specific thing — a credit conflict, an AHJ correction, a wall assembly question? Tell us what's going on and we'll match you with the right expert on our team for a 15-minute call.
- Matched to your situation — the right expert for your specific question
- Initial call typically within 1 business day
- Written recap after, so you have it on record
We review your plans, build your credit strategy, and hand back a permit-ready compliance package.
- Credit summary and recommendations
- Subcontractor homework
- Modified credit sheet
- Email follow-up until your submission lands
Built for how Washington actually builds
Mac, mobile, or PC.
Open it anywhere. No macros, no antivirus blocks, no Windows-only install.
Real-time math.
Pick credits, watch your status update. No clicking through tabs to figure out why your sheet won't total.
Plain-English explanations.
Every credit option includes the WAC citation and what it actually means in build terms.
Frequently asked questions
How much does WSEC compliance cost?
The 2021 WSEC-R itself is free to download from the Washington State Building Code Council. The compliance work — running the C3 worksheet, generating certificates, getting a HERS rating if you use the ERI path — is what costs time and money. wsec.ai is being priced to undercut a HERS-only path for builders who can land their credits prescriptively.
Do I need a HERS rater for the prescriptive path?
No. The prescriptive path (R406) and the ENERGY STAR path are documentable without a HERS rater. The ERI path (R408) requires a HERS rater because the score is the compliance metric. wsec.ai will support all three paths; only the ERI path requires outside verification.
What is the WSU C3 calculator and is wsec.ai related to it?
The WSU C3 calculator is a macro-enabled Excel workbook published by the Washington State University Energy Program. wsec.ai is independent of WSU. Our calculator implements credit logic from the Washington Administrative Code directly — we do not reproduce or rely on WSU's C3 spreadsheet. wsec.ai is not endorsed by, affiliated with, or approved by WSU or the Washington State Building Code Council.
What does it mean that the engine is "audited against the WAC"?
Energy code compliance ultimately rests on the Washington Administrative Code (WAC) — the legal source of the 2021 WSEC-R. The published 2021 WSEC-R book and the WSU C3 spreadsheet are widely used reference tools, but both contain known minor deviations from the WAC. wsec.ai's compliance engine reads from the WAC directly. All R406 credit values were certified line-by-line against WAC 51-11R-40610, 40620, and 40621 on May 8, 2026. Re-audit triggers on any WAC amendment.
Is wsec.ai approved by Washington State?
No. The 2021 WSEC-R does not have a state approval process for compliance software. Building officials accept whatever documentation demonstrates compliance — the WSU C3 worksheet, hand calculations, or third-party tools. wsec.ai is designed to produce the same outputs your jurisdiction already accepts, and an independent audit of the engine is in progress. We're not putting this in your hands until we're absolutely sure it's ready.
Does wsec.ai work for the Seattle Energy Code?
Partially. The Seattle Energy Code (SEC) amends the WSEC-R with stricter requirements. wsec.ai's prescriptive path covers WSEC-R baseline; Seattle-specific amendments are covered in our Seattle Energy Code guide.