Title 24 & CALGreen for New Construction in California

What Title 24 means for new construction

Title 24 is part of the California Code of Regulations covering building standards. Part 6 — the Building Energy Efficiency Standards — governs energy performance: envelope (insulation, glazing, air sealing), HVAC, water heating, ventilation, lighting, and on-site renewables. The California Energy Commission (CEC) updates the standards on a three-year cycle. The 2025 California Energy Code is effective for building permits filed on or after January 1, 2026, and it is the code in force for any ground-up project pulling permits in our active window.

Compliance is demonstrated via either a prescriptive path (meeting fixed component requirements) or a performance path (energy modeling against a budget). Performance modeling is the practical path for nearly every custom home and small multifamily project — it gives the design team flexibility to trade higher performance in one area for relief in another.

What CALGreen means for new construction

CALGreen (Title 24, Part 11) is California's green building code. It establishes mandatory requirements and tiered voluntary measures (Tier 1, Tier 2) covering planning and design, energy efficiency, water efficiency, material conservation and resource efficiency, environmental quality (including indoor air quality), and construction-waste management. Many jurisdictions adopt CALGreen Tier 1 or Tier 2 as mandatory locally — particularly in the Bay Area and on multifamily projects.

2025 California Energy Code — what changes for residential

The 2025 update strengthens heat-pump water heating and heat-pump space heating expectations on new low-rise residential construction, expands electric-readiness requirements (so future appliance swaps from gas to electric are simpler), tightens ventilation and indoor-air-quality requirements, and continues the residential PV and battery-storage framework introduced in earlier code cycles. The CEC is the authoritative source — we design to the code in force at permit filing, not to a generalized assumption.

Energy modeling and envelope

Performance-path compliance starts with an energy model produced by a CEC-approved Title 24 consultant using CBECC-Res or an approved compliance software. The model balances envelope (R-values, U-factors, SHGC), air sealing, HVAC efficiency, water-heating strategy, ventilation, and renewables against the budget. Envelope choices made at schematic — wall assembly, window selection, roof and slab insulation, air-barrier strategy — drive the model more than equipment selection does later.

HVAC, heat pumps, and water heating

The practical path for most new homes under the 2025 code is heat-pump space heating and heat-pump water heating, paired with high-performance envelope and continuous balanced ventilation. Mixed-fuel paths remain possible on the performance path but typically require offsetting envelope or system upgrades. Many Bay Area cities have adopted local reach codes that go further — effectively requiring all-electric on most new residential construction. We design to the local code at permit filing.

Ventilation and indoor air quality

Title 24 and CALGreen both push continuous balanced ventilation, lower-VOC materials, and controlled local exhaust (kitchens, baths, laundry). The practical implication is that ventilation is a designed system — typically an HRV or ERV on tighter envelopes — not an afterthought. Coordination with HVAC, building envelope, and air-sealing strategy is part of the integrated MEP package.

PV, battery storage, and EV readiness

New low-rise residential construction in California has carried a mandatory residential PV requirement since 2020. The 2025 code continues that framework, with sizing tied to the modeled annual electricity use and roof area, and provides battery-storage credit pathways. EV-ready electrical infrastructure (raceway, panel capacity) is required for most new construction; the specific quantity and configuration depend on project type. Future-proofing the panel and the conduit layout at construction is far cheaper than retrofitting later.

HERS verification

HERS (Home Energy Rating System) verification is required on performance-path projects to confirm field installation matches the modeled performance — duct leakage testing, refrigerant charge verification, envelope leakage testing, and quality insulation installation are common HERS measures. The HERS rater is independent of the contractor; we sequence HERS inspections into the construction schedule from the start.

CALGreen water efficiency, materials, and waste

CALGreen mandates low-flow plumbing fixtures, water-budget calculations, separation and recovery of construction and demolition waste (typically 65% diversion at minimum), use of regional and low-emitting materials in some assemblies, and indoor-air-quality measures. Many jurisdictions enforce Tier 1 or Tier 2 measures on top of the statewide baseline — particularly on multifamily.

How Title 24 applies differently across ADUs, custom homes, and multifamily

ADUs have their own compliance framework and certain relief pathways under Title 24 (PV is not always required on detached ADUs of certain sizes, for example). Custom homes are full low-rise residential compliance. Small multifamily (1–3 stories, low-rise) uses the residential envelope; mid-rise (4+ stories) uses the nonresidential envelope. Each path has different prescriptive and performance trade-offs. We confirm the applicable framework at feasibility.

Cost and timeline implications

Title 24 compliance — heat pumps, ventilation, PV, battery, EV readiness, and envelope upgrades — adds a measurable but bracketable line item. CALGreen waste management and water-efficiency adds modest cost. The schedule impact is in design: late changes to envelope, HVAC, or PV layout cause expensive re-modeling and plan-check resubmittals. Code strategy decided at schematic costs far less than code strategy decided at plan-check.

Frequently asked questions

Does the 2025 California Energy Code apply to my project?

If your building permit is filed on or after January 1, 2026, yes. The California Energy Commission is the authoritative source for effective dates and code updates.

Do I have to install heat pumps?

Not strictly — but the practical performance-path under the 2025 code, combined with many Bay Area local reach codes, heavily favors heat-pump space heating and heat-pump water heating. Mixed-fuel paths are still possible on the performance path but typically require offsetting envelope or system upgrades.

Is PV mandatory on my new home?

Mandatory residential PV has been part of California's energy code since 2020 for new low-rise residential. Sizing is tied to modeled annual electricity use, roof area, and available battery-storage credits. ADUs and certain project types have specific relief pathways.

Does CALGreen apply to small projects?

CALGreen applies to nearly every new building construction project in California. Many jurisdictions enforce additional Tier 1 or Tier 2 measures locally — especially on multifamily.

What is HERS verification?

Field verification performed by an independent HERS rater to confirm installed performance matches the energy model — duct leakage, envelope leakage, refrigerant charge, and quality insulation installation are common measures. We sequence HERS into the construction schedule.

Can I keep gas appliances?

Sometimes, depending on the local code in force at permit filing. The 2025 statewide code allows mixed-fuel paths via the performance method, but many Bay Area cities have local reach codes that effectively require all-electric. We design to the local code in force at permit filing.

Will I need a battery with my PV?

Not always — battery storage is a credit pathway under the energy code that can reduce PV size or offset other measures. Many projects skip battery; some include it to capture credits or owner-preference resilience. The energy model makes the trade-off explicit.

When should we make code decisions?

At schematic design. Envelope, HVAC, water-heating, and PV strategy decided at schematic costs a fraction of the same decisions made at plan-check or construction. We integrate Title 24 and CALGreen into design-build from day one.

Official sources

• California Energy Commission — 2025 Building Energy Efficiency Standards ↗

  California Energy Commission

  Authoritative source for the 2025 Title 24, Part 6 standards effective January 1, 2026.

• California Energy Commission — Building Energy Efficiency Standards (overview) ↗

  California Energy Commission

  Statewide energy code overview, history, and update cycle.

• California Building Standards Commission — CALGreen ↗

  California Department of General Services

  CALGreen (Title 24, Part 11) mandatory requirements and Tier 1 / Tier 2 voluntary measures.

• CBECC-Res — Title 24 Compliance Software ↗

  California Energy Commission

  CEC-approved residential performance-path compliance software reference.

• California Public Utilities Commission — Building Decarbonization ↗

  CPUC

  Statewide building electrification and decarbonization program context.

Related pages

• New Construction overview →

  Where energy-code and CALGreen decisions live inside the full design-build process.

• Custom Homes →

  Where Title 24 and CALGreen decisions live in the design-build process.

• Small Multifamily (2–6 unit) →

  Residential vs nonresidential Title 24 envelope and CALGreen on multifamily.

• New Construction Cost →

  How heat-pump, PV, battery, and envelope upgrades affect the budget.

• Permit Timeline →

  Where late code changes blow up plan-check schedules.