Title 24 (CA Energy Code)

Title 24 refers to the California Code of Regulations' building standards, and in everyday construction usage it most often means the state's Building Energy Efficiency Standards — the energy code that new buildings and many renovations must meet. These standards set requirements for insulation, windows, heating and cooling equipment, water heating, lighting, and, increasingly, solar and electrification measures, with the goal of reducing energy use in California buildings.

Title 24 matters for ADU projects and additions because a new dwelling unit generally has to demonstrate compliance as part of the permit submittal. That usually means including energy calculations or forms with the plans, which a building department checks during plan review. For a conversion or a smaller unit the requirements may be lighter than for ground-up new construction, but energy compliance is still part of the path to approval.

In practice, Title 24 is one of several code layers a project must satisfy alongside the building, electrical, plumbing, and mechanical codes, and it influences design choices and budget — equipment efficiency, window specs, and insulation all flow from it. California also has a green building standards code (often called CALGreen) that addresses broader sustainability measures; it is related to but distinct from the energy standards people usually mean by "Title 24."

The standards are updated on a multi-year cycle, and which edition applies depends on when a permit application is deemed complete, so the specific requirements change over time. Local jurisdictions may also adopt amendments or reach codes that go beyond the state baseline. This is a general overview specific to California and not engineering or code advice — confirm the current Title 24 requirements for your project with your local building department or a qualified energy consultant. For how energy upgrades factor into a budget, see how much an ADU costs.