Title 24 Energy Requirements Explained

If you're planning any kind of construction project in California — whether it's a new home, an ADU, a room addition, or even a window replacement — you're going to encounter Title 24. It's one of the most common sources of confusion (and delay) in the California permit process.

This guide breaks down what Title 24 actually requires, which projects trigger compliance, and what the process looks like from start to permit approval. We've written it for homeowners, contractors, and investors who need practical answers rather than regulatory jargon.

What Is Title 24?

Title 24 is the California Building Standards Code. It contains all of the state's building regulations across multiple parts — structural, plumbing, electrical, fire, and more. However, when most people say "Title 24," they're referring specifically to Part 6: the Building Energy Efficiency Standards.

Part 6 sets minimum energy performance requirements for residential and nonresidential buildings. It covers everything from insulation and windows to HVAC systems, water heaters, lighting, and solar panels. The standards are developed and updated by the California Energy Commission (CEC) on a three-year code cycle.

The purpose is straightforward: reduce energy consumption and greenhouse gas emissions from buildings. California buildings account for a significant share of the state's total energy use, and each code update pushes efficiency requirements further.

Which Projects Need Title 24 Compliance?

The general rule: if your project requires a building permit and involves changes to energy-consuming building components, it triggers Title 24 compliance.

Projects That Require Title 24

• New residential construction — custom homes, tract homes, townhomes
• Accessory Dwelling Units (ADUs) — detached, attached, garage conversions, junior ADUs
• Room additions — even adding one square foot of conditioned space triggers compliance
• Kitchen and bathroom remodels — when they involve changes to lighting, HVAC, or insulation
• Window and door replacements — when the frame is replaced (not just reglazing)
• HVAC system replacements — furnace, air conditioner, or heat pump changeouts
• Water heater replacements — especially conversions to heat pump water heaters
• Reroofing — when it triggers cool roof requirements in certain climate zones
• Lighting changes — significant modifications to permanent lighting systems

Projects That Generally Do Not Require Title 24

• Cosmetic work — painting, flooring, cabinetry, countertops
• Repairs using identical replacement components with no performance change
• Window reglazing or sash replacement without changing the frame
• Work that does not require a building permit

What Title 24 Covers

Title 24 energy requirements are organized around five major building systems. Each system has both mandatory measures (requirements that apply to every project regardless of compliance path) and additional requirements that depend on your chosen compliance method.

1. Building Envelope

The "envelope" is everything that separates inside from outside — walls, roof, floor, windows, and doors. Title 24 regulates:

• Insulation R-values — minimum insulation requirements for walls, ceilings, floors, and foundations that vary by climate zone
• Window performance — U-factor (heat transfer rate) and Solar Heat Gain Coefficient (SHGC) requirements
• Air sealing — building envelope tightness and air barrier requirements to prevent unwanted air leakage
• Cool roofs — minimum solar reflectance requirements in certain climate zones to reduce cooling loads

2. HVAC Systems (Heating, Ventilation & Air Conditioning)

HVAC is typically the largest energy consumer in California homes. Title 24 addresses:

• Equipment efficiency — minimum efficiency ratings (SEER, HSPF, AFUE) for heating and cooling equipment
• Duct sealing and insulation — ducts in unconditioned spaces must be insulated to R-6 or R-8 (depending on climate zone) and sealed to prevent leakage
• Ventilation — mechanical ventilation requirements for indoor air quality
• Load calculations — heating and cooling loads must be calculated to ensure proper equipment sizing
• Thermostat requirements — smart thermostats required for heat pump systems to minimize supplemental resistance heating

3. Water Heating

• Heat pump water heaters — now required or strongly incentivized for most new construction projects
• Pipe insulation — hot water distribution efficiency requirements
• Solar-ready plumbing — pre-plumbing for potential solar water heating systems
• Ventilation for heat pump water heaters — adequate air volume or ducting to ensure proper operation

4. Lighting

• High-efficacy lighting — LED or equivalent required throughout the home
• Lighting controls — dimmers, vacancy/occupancy sensors, and daylight-responsive controls in applicable areas
• Outdoor lighting — motion sensor and photocell requirements for exterior fixtures

5. Solar Photovoltaic (PV) & Battery Storage

• Solar PV systems — required on most new low-rise residential buildings (three stories or fewer), with system size based on the home's conditioned floor area and climate zone
• Battery storage readiness — new homes must include dedicated space, conduit routing, and electrical panel capacity for a future battery storage system
• Solar-ready roof area — minimum unshaded roof area reserved for current or future solar panels

California's 16 Climate Zones

California does not apply a one-size-fits-all energy standard. The state is divided into 16 climate zones, each with distinct temperature patterns, humidity levels, and heating/cooling demands. Title 24 requirements — from insulation R-values to window SHGC limits — change based on which climate zone your project is located in.

Your climate zone determines specific prescriptive requirements. For example, windows in Climate Zone 15 (desert) require an SHGC of 0.23 or lower to limit solar heat gain, while Climate Zone 1 (north coast) has no SHGC requirement because cooling demand is minimal.

You can look up your project's climate zone on the California Energy Commission's website, or contact us with your project address and we'll identify it for you.

Prescriptive vs. Performance: Two Paths to Compliance

Title 24 provides two methods to demonstrate that a project meets the energy code. Both are equally valid for permitting purposes.

Prescriptive Path

The prescriptive path is a checklist approach. Each building component must individually meet a specific efficiency threshold for your climate zone. For example:

• Ceiling insulation: R-38 minimum
• Wall insulation: R-15 or R-21 (varies by climate zone)
• Windows: U-factor of 0.30 or less, SHGC of 0.23 or less (varies by climate zone)
• HVAC: meets minimum efficiency ratings

The advantage is simplicity — if every component checks the box, you're compliant. The disadvantage is no flexibility. If one component falls short, even slightly, you cannot compensate with better performance elsewhere.

Performance Path

The performance path uses energy modeling software (CBECC-Res for residential projects) to evaluate the building as a whole. Instead of checking each component individually, the software compares your proposed design's total energy use against a "standard design" baseline.

This allows trade-offs. For example, if your design has more window area than the prescriptive limit, you might compensate with a higher-efficiency HVAC system or additional insulation. As long as the total modeled energy use does not exceed the baseline budget, the building complies.

The performance path is more common for:

• Custom homes with design features that don't fit prescriptive checkboxes
• Projects with large window-to-wall ratios
• Complex projects like multi-zone HVAC layouts
• Projects seeking to optimize between construction cost and energy performance

CF-1R, CF-2R, CF-3R: The Compliance Forms

Title 24 compliance is documented through a series of standard forms. For residential projects, the three main forms are:

The CF-1R is what you need to submit with your permit application. It must be registered with the California Energy Commission's HERS registry before the building department will accept it. At Andalusia Drafting, we prepare and register CF-1R documents as part of our Title 24 compliance services.

The CF-2R and CF-3R come later in the process. Your contractor is responsible for the CF-2R (confirming proper installation), and a certified HERS rater handles the CF-3R (field verification testing). Both must be completed and registered before the building department will schedule a final inspection.

Common Projects & Their Title 24 Requirements

New Custom Homes

New homes face the most comprehensive requirements. Every system is covered — envelope, HVAC, water heating, lighting, solar PV, and battery storage readiness. The performance path is common for custom homes because it provides design flexibility. A full CF-1R package and HERS testing are required.

Accessory Dwelling Units (ADUs)

ADUs are classified as new construction and must meet the same energy code requirements as a new home. This applies to detached ADUs, attached ADUs, garage conversions, and junior ADUs (JADUs). Solar PV requirements may apply depending on the ADU size and configuration. See our ADU drafting services for complete permit-ready plans with Title 24 included.

Room Additions

Adding conditioned space to an existing home — even one square foot — triggers Title 24 compliance. The good news: for additions, the energy model compares the home's energy use before and after the addition, which is typically less strict than meeting the full new-construction standard. The code offers three modeling options: addition alone, existing + addition + alteration, or modeling everything as new construction. See our remodel and addition services.

Window Replacements

Replacing windows (including the frame) is classified as an alteration under Title 24. Replacement windows must meet U-factor and SHGC requirements for your climate zone. For projects replacing 75 square feet or more of window area, standard prescriptive values apply. For less than 75 square feet, slightly relaxed thresholds are allowed (U-factor of 0.40 or less, SHGC of 0.35 or less). If only the glass or sash is replaced without a new frame, Title 24 generally does not apply.

HVAC Replacements

Replacing a furnace, air conditioner, or heat pump triggers Title 24 and often requires HERS field verification for duct leakage testing and refrigerant charge. Under the 2025 code, some single-family air conditioner replacements may require upgrading to a heat pump system. Load calculations are required for all new heating and cooling equipment to ensure proper sizing.

Kitchen & Bathroom Remodels

Title 24 is triggered when the remodel involves changes to lighting systems, HVAC ductwork, insulation, or windows. A full kitchen remodel that moves walls, adds recessed lighting, and replaces windows will require compliance documentation. A cosmetic update (new cabinets, counters, and paint) typically will not.

The 2025 Energy Code Update (Effective January 1, 2026)

California updates its energy code every three years. The 2025 Building Energy Efficiency Standards were adopted by the California Energy Commission and took effect on January 1, 2026. Any project submitting a building permit application on or after that date must comply with the new code.

Here are the key changes that affect residential projects:

Heat Pump Expansion

The 2025 code significantly expands heat pump requirements. Heat pump space heating is now the baseline expectation for new construction, moving away from gas furnaces. In some cases, homeowners replacing an existing air conditioner in a single-family home may be required to install a heat pump rather than a like-for-like AC replacement. Third-party refrigerant charge verification for heat pumps is now required in all climate zones, not just select ones.

Stricter Building Envelope Standards

The 2025 code introduces lower U-factor requirements for windows and framed walls in single-family homes, reflecting advances in window technology and insulation materials. A new prescriptive pathway for cathedral/vaulted ceilings provides clearer guidance for these complex roof assemblies.

Battery Storage Integration

Buildings with photovoltaic systems now face expanded battery storage requirements. This goes beyond "battery-ready" wiring to encourage or require actual battery installation in conjunction with solar PV, supporting grid resilience and time-of-use energy management.

Electric-Ready Infrastructure

New homes must include electric-ready panels and infrastructure to support future electrification of gas appliances. This includes panel capacity, conduit routing, and outlet provisions for electric cooking, clothes drying, and space/water heating equipment.

What Happens If You Don't Comply

The practical cost of non-compliance is usually measured in project delays rather than fines. A permit application bounced back for missing Title 24 documentation can add weeks or months to your timeline. Getting compliance right upfront is always the more cost-effective approach.

Frequently Asked Questions