Title 24 vs CALGreen: What Is the Difference?
They are not alternatives — CALGreen is part of Title 24. Part 6 is the Energy Code and Part 11 is CALGreen. Different subject matter, separate documentation, and a project can easily need both.
The confusion comes from the naming
Title 24 is the California Building Standards Code as a whole, divided into numbered parts. Part 6 is the California Energy Code. Part 11 is the California Green Building Standards Code, universally called CALGreen.
So "Title 24 versus CALGreen" compares a whole code with one of its own parts. When a building department asks for "your Title 24" it means Part 6 energy documentation — that shorthand is where the muddle starts, and it is worth being precise about because the two parts ask for genuinely different things.
What each one is about
Part 6 is energy: the envelope, lighting, mechanical systems, water heating, and increasingly solar and storage. Its question is how much energy the building will use.
Part 11 is broader environmental performance: water efficiency and conservation, construction waste diversion, material selection and pollutant control, and indoor environmental quality. Its question is the building's wider footprint — including things Part 6 has no view on at all, like how much construction waste leaves the site.
They overlap least where people assume they overlap most. A building can be highly efficient under Part 6 and still have nothing to say about waste diversion or water fixtures.
CALGreen has mandatory measures and voluntary tiers
This is the structural difference that catches projects out. CALGreen contains mandatory measures that apply statewide, and above those it defines voluntary tiers of higher performance.
The tiers matter because a local jurisdiction can adopt one, turning what is voluntary statewide into a requirement locally. So the CALGreen scope for a given project depends on where it is in a way the Part 6 scope generally does not.
Separate documentation
Part 6 compliance produces the certificate families — CF1R and its relatives on residential work, the NRCC series on nonresidential. CALGreen compliance is documented separately, often on a jurisdiction's own checklist, and it is verified differently.
A complete energy submittal therefore does nothing to satisfy CALGreen, and a completed CALGreen checklist does nothing to satisfy Part 6. Projects that assume one covers the other are the ones held at plan check.
What this means practically
Ask the building department which parts apply to your scope, and treat them as two separate deliverables with two separate owners. Energy compliance is a modelling and documentation exercise; CALGreen is substantially a construction-practice and procurement exercise, and the people who can answer for it are often not the same people.