Definition
California Title 24 Part 6 is the state Building Energy Efficiency Standard requiring solar PV on most new low-rise residential construction since 2020 and adding battery storage requirements for new non-residential and high-rise residential since 2023.
Quick Facts
| Field | Detail |
|---|---|
| Term | Title 24 — California Building Energy Efficiency Standard |
| Category | US Solar Codes / California |
| Engineering Discipline | Energy Code Compliance, Solar Design |
| Latest Edition | 2022 (effective January 2023) |
| Difficulty Level | Intermediate |
Title 24 Structure
Part 6 — Energy Code
- Building envelope, HVAC, lighting, water heating, plug loads.
- Solar PV mandate (since 2020).
- Battery storage mandate (since 2023 for non-res / high-rise res).
Part 11 — CALGreen
- Sustainable construction (water, materials, indoor air).
- Separate from Part 6 but often referenced together.
Solar PV Mandate Details
Coverage
- Single-family homes (new).
- Multifamily up to 3 stories.
- New ADUs > 700 sf in some jurisdictions.
Exemptions
- Severely shaded sites (TSRF < 70%).
- Roof area insufficient (< 80 sf usable).
- Substantially oriented (N-facing roof only).
- Site solar resource < 70% of climate-zone reference.
Sizing
TDV calculation in CBECC. Typical results: 2–4 kW per dwelling. Larger for high-conditioning climates (Coastal: smaller; Inland Empire / Central Valley: larger).
Battery Storage Mandate (2023)
Coverage
- New non-residential (offices, retail).
- New high-rise residential (>3 stories).
Sizing
Tied to building Tier of demand. Typical: 10–25 kWh per 5,000 sf of building.
Compliance Paths
Prescriptive
Meet specific requirements per climate zone for envelope, HVAC, solar size. Easier for designers, less flexibility.
Performance
Demonstrate building total source energy ≤ a reference building’s source energy. More design flexibility.
Mixed-fuel reference vs. all-electric
2022 code favors all-electric construction; mixed-fuel buildings face stricter performance targets.
Solar-Ready & Battery-Ready
For homes not installing full solar (exempted), Title 24 requires “solar-ready”:
- Reserved roof area ≥ 250 sf with appropriate solar window.
- Conduit pathway from roof to electrical room.
- Service capacity for future expansion.
Battery-ready (2022 code):
- Dedicated 200 A subpanel or service compartment for future battery.
- Pre-wired EVSE outlet in garage.
Permitting Implications
- Title 24 Form CF-1R submitted with permit application.
- Solar system size must match the CF-1R calculation.
- AHJ reviews both CF-1R and the actual SLD for consistency.
- Re-roof of existing homes may require solar evaluation in some jurisdictions.
Common Mistakes
- Designing solar without aligning with Title 24 TDV calculation.
- Skipping solar-ready provisions when claiming exemption.
- Outdated CBECC software version (incompatible with code edition).
- Missing battery-ready provisions in 2023+ non-residential projects.
- Ignoring CALGreen separate requirements.
Best Practices
- Use latest CBECC version matching the AHJ’s adopted code edition.
- Coordinate solar design with the architect’s energy report.
- Document exemptions thoroughly when claiming.
- Pair Title 24 + NEM 3.0 + Federal ITC for max customer value.
Standards & Certifications
- California Code of Regulations, Title 24, Part 6.
- CBECC (California Building Energy Code Compliance) software.
- CALGreen (Title 24, Part 11).
- ASHRAE 90.1 (referenced for some provisions).
Key Takeaways
- California Title 24 Part 6 mandates solar PV on new low-rise residential since 2020 and battery storage on new non-residential / high-rise residential since 2023.
- Solar sizing via TDV (Time-Dependent Valuation) calculation in CBECC.
- Exemptions exist for severely shaded, oriented, or roof-constrained sites.
- “Solar-ready” and “battery-ready” provisions apply to exempted properties.
- Compliance verified via Form CF-1R submitted with the building permit.
Frequently Asked Questions
10 commonly searched questions about Title 24.
What is Title 24?
California Title 24 Part 6 is the state Building Energy Efficiency Standard regulating energy use in new construction. The 2019 update (effective 2020) added a mandatory solar PV requirement for low-rise residential. The 2022 update (effective 2023) added battery storage requirements for non-residential and high-rise residential.
Is solar mandatory for new homes in California?
Yes, since January 1, 2020, most new low-rise residential construction (single-family and multifamily up to 3 stories) requires installed solar PV sized per a TDV formula. Some exceptions for heavily shaded or oriented sites.
How is solar size determined under Title 24?
Based on a Time-Dependent Valuation (TDV) calculation that targets net energy consumption. Typical sizing: 1.0–1.5 W per square foot of conditioned space, but the actual requirement varies by climate zone and building type.
Is battery storage required by Title 24?
Battery storage is required for some non-residential and high-rise residential since 2023. For low-rise residential, battery is not mandatory but is often added to optimize TDV credit and NEM 3.0 economics.
What is solar-ready / battery-ready?
Title 24 also requires new homes that don't get full solar to include solar-ready provisions: reserved roof area, conduit pathway, electrical service capacity. Battery-ready: dedicated electrical service compartment for future storage installation.
Is Title 24 the same as CALGreen?
No, but related. Title 24 Part 6 is the energy code; CALGreen (Title 24 Part 11) is the green building standard. CALGreen includes additional sustainability requirements beyond energy.
How is Title 24 enforced?
Through building permit review by local AHJs. Architects/designers submit a Title 24 energy compliance report (Form CF-1R) prepared in CBECC or other certified software.
When was Title 24 last updated?
California adopts the energy code on a 3-year cycle. Major updates: 2019 (effective 2020 – solar mandate), 2022 (effective 2023 – storage), 2025 (effective 2026 – expected expansion).
Does Title 24 affect existing buildings?
Major renovations triggering electrical or HVAC upgrades may invoke Title 24 provisions. Re-roof projects in some jurisdictions trigger solar evaluation.
What software calculates Title 24 compliance?
CBECC-Res (residential), CBECC-Com (commercial), EnergyPro, EnergyAdept. Plus third-party platforms like Energy Toolbase for performance-path compliance.
Need engineering-backed solar designs?
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