California Title 24 sets the energy rules you must meet when remodeling a home. You’ll trigger requirements for windows, insulation, ducts, lighting, HVAC, and electrical systems based on the scope of work, not every repair. The 2025 code tightens standards with more duct sealing, stronger ventilation, and new electrification options, plus solar and battery mandates for many projects. You’ll use HERS testing and California-certified energy models to demonstrate compliance before permits. If you keep reading, more specifics await.

What California Title 24 Covers for Home Remodels

California Title 24 sets the rules for what counts as a remodel from an energy-efficiency standpoint, so you’ll want to know when changes trigger its requirements.

In short, certain renovations activate compliance, while some repairs do not. If you replace or enlarge windows and doors, upgrade HVAC systems, modify ducts, or alter insulation, you’re facing Title 24 compliance.

Lighting changes in kitchens, bathrooms, and garages, plus water heater upgrades, also count toward energy upgrades.

Distinctions matter: alterations, which modify energy usage, require full compliance certification, whereas simple repairs don’t.

Distinctions matter: alterations require full energy-compliance certification, while simple repairs do not.

Building envelope work—roofs, exterior walls, and insulated floors—can trigger standards, especially when you add space or change usage.

Permits and pre-construction documentation often formalize these compliance challenges before any work begins.

Key Changes for 2025 Energy Code Adoption

The 2025 Energy Code adoption brings notable shifts that affect nearly every project, from new builds to alterations.

You’ll face more stringent requirements across buildings, reflecting a roughly 30% increase in stringency versus 2022 standards. The scope now covers new construction, additions, and alterations for residential and nonresidential buildings, with single-zone heat pump baselines expanded.

HVAC and envelope rules tighten, including mandatory duct sealing, an R-22 (or 0.043 U-factor) ceiling/roof insulation, and reduced whole-house fan and attic vent area.

Electrification expands options for space heating, water heating, cooking, and pool heating, accelerating the shift from natural gas.

PV and battery mandates grow, promoting energy resilience. Expect enhanced lighting controls and sensors, all aligning under energy efficiency goals within the building codes framework.

How Ventilation and Heat Pumps Impact Remodels

As the 2025 Energy Code expands, ventilation and heat pump requirements increasingly shape remodel projects.

You’ll see the minimum ventilation volume rise to 1 cfm per 100 sq. ft. plus 7.5 cfm per occupant, with occupants based on bedrooms. A 3-bedroom, 1,800 sq. ft. townhouse needs about 48 cfm continuous ventilation, and the new formula uses the larger of occupant-based or area-based rates.

Whole-house ventilation becomes mandatory, via a continuous bathroom fan or central HVAC supply/return. In multifamily buildings, balanced ventilation is required, and HERV paths may apply to improve cost-effectiveness.

Whole-house ventilation becomes mandatory via continuous bathroom fan or central HVAC supply/return; balanced ventilation required in multifamily buildings.

Heat pump efficiency matters, with updated VRF options and prescriptive verification by HERS raters. Expect stronger duct sealing, testing, and upgraded airflow controls as you remodel.

Ventilation strategies and heat pump efficiency matter.

Solar, Batteries, and Electric-Ready Requirements

Solar, Batteries, and Electric-Ready Requirements are shaping how you plan new residential, commercial, and multifamily projects.

Title 24 mandates solar PV systems for new builds, sized by floor area and occupancy factors, with calculations like kWPVdc = (CFA × A) / 1000.

New 2025 updates raise PV capacity in certain occupancies and apply to nonresidential and high-rise multifamily projects.

Battery storage is now required alongside PV for many commercial properties, sized by Section 140.10 equations, with a 25% PV size reduction when paired with qualifying storage.

You’ll use tools such as the Solar PV Calculator and California Solar Shade Analysis to verify access and sizing.

Compliance may apply from January 1, 2026, for permits issued afterward.

solar panel integration, battery storage requirements.

Compliance Tools and Resources for Remodel Projects

Compliance tools and resources for remodel projects keep you aligned with Title 24 requirements at every stage.

You’ll use HERS verification for mechanical changes, additions, and major remodels to confirm post-installation efficiency, performed by certified HERS raters.

Title 24 calculations happen before permits, with energy models submitted by your energy consultant and generated through California Certified Energy Reading programs.

Title 24 calculations precede permits, using energy models crafted via California Certified Energy Reading programs.

CEC-approved tools, like EnergyPro and CBECC, simulate envelope, lighting, HVAC, and water heating performance, ensuring official permit documents are valid.

Compliance forms help identify the right Part 6 forms, while MAEDbS lists approved luminaires your designer must specify.

Local AHJs verify JA-marked products and forms, guiding your permitting, planning, and post-construction commissioning alongside energy consultants for continued compliance.

Wrapping It Up

You’ll find California Title 24 remodeling rules clearer than you’d expect, with practical steps you can take now. As codes evolve, focus on energy efficiency, ventilation, and the growing role of heat pumps, solar, and storage. Keep plans aligned with 2025 changes, verify requirements for electric-ready spaces, and use available compliance tools to stay on track. By staying proactive and organized, you’ll simplify approvals, save energy, and deliver a safer, more comfortable home renovation.