If a project isn't in California, the odds are good that ASHRAE 90.1 ("Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings," jointly developed by ASHRAE and the Illuminating Engineering Society) is the standard actually governing it, whether the state's own code names it directly or the IECC references it as a compliance alternative. It's the standard most developers outside California have heard of but never really had explained, mostly because their energy consultant just handles it quietly in the background.
Why it's worth it: fact-checked, not generic
Many states adopt 90.1 directly as their commercial energy code, and the IECC's own commercial chapter allows compliance via reference to 90.1 as an alternative path: it's binding in practice even where the code goes by another name.
C-PACE financing commonly runs on the same kind of above-code energy model your compliance work already produces, often an ASHRAE 90.1 baseline-building comparison, though each program sets its own methodology. For projects that broke ground before July 1, 2026, the 90.1 edition tied to your placed-in-service date still matters for a 179D claim.
Performance-path 179D claims, utility incentive programs, and LEED submittals all run on 90.1's Appendix G baseline-building methodology, not an informal "beat code by X%" shortcut.
90.1-2022 is the edition most current codes and federal programs reference today. 90.1-2025 is published but not yet adopted anywhere: don't assume the newest edition is what your jurisdiction actually enforces.
One standard, five systems
90.1 covers building envelope, HVAC, service water heating, power distribution, and lighting, not just the mechanical systems most cost estimates focus on. A design that passes on HVAC and fails on lighting power density still fails the standard. Buildwiser checks all five system categories together, using whichever edition your specific jurisdiction has actually adopted.
Prescriptive tables, or the full performance model
The prescriptive path is a set of fixed minimum requirements per system: fast, but conservative. Appendix G models the whole building's energy performance against a code-minimum baseline, which often clears code more cheaply but requires the full energy model that a prescriptive checklist skips. Buildwiser runs both and shows which one actually wins for your specific building, rather than defaulting to whichever path is faster to document.
How much will it cost for your project to go ASHRAE 90.1?
Free directional numbers in minutes, run against your actual project.
Get my numbersNot every jurisdiction is on the same edition
ASHRAE publishes a new edition on a multi-year cycle (recent editions include 90.1-2019 and 90.1-2022), but adoption isn't uniform. A state or city can be enforcing an older edition years after a newer one is published, and modeling to the wrong one is exactly the kind of mismatch that surfaces at permit review, not before. Illustrative modeling suggests projects that confirm the right edition early avoid $25K+ in average rework versus catching the gap at submission.
- Edition matched to what your specific jurisdiction actually enforces, not just the newest one published
- Full system scope: envelope, HVAC, lighting, power, service water heating
- Both compliance paths modeled, so you know which one is actually cheaper
- Re-run instantly on any design change
How much will it cost for your project to go ASHRAE 90.1?
Confirm the right edition and compliance path before you submit.
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