Introduction
The 2025 update to California’s Title 24 Energy Code (effective January 1, 2026) represents a significant shift in how buildings are designed and evaluated. Rather than introducing entirely new rules, the update tightens performance expectations and accelerates the transition toward electrification and low-carbon design.
This insight focuses specifically on the key changes from the 2022 code, and how they impact energy modeling, ADUs, HVAC systems, and compliance workflows.
What Changed from 2022 to 2025 Code?
The transition from 2022 to 2025 is defined by a clear shift in design priorities.
Key Changes
- Stronger push toward electrification (heat pump systems)
- Reduced reliance on natural gas systems
- Stricter energy performance targets
- Increased focus on battery-ready and grid-responsive design
- Enhanced indoor air quality (IAQ) standards
How Do These Changes Affect Residential vs Non-Residential Buildings?
Residential Buildings
- Transition toward all-electric homes
- Heat pumps becoming the default compliance pathway
- Greater integration of solar + battery-ready systems
Non-Residential Buildings
- Higher emphasis on HVAC system efficiency and controls
- Increased requirements for ventilation and IAQ
- More reliance on energy modeling for compliance
Major Code Changes in 2025
- Electrification as a Primary Strategy
- Heat pumps increasingly replace gas heating systems
- Electrification is now the preferred compliance path
- Stricter Energy Performance Targets
- Lower allowable energy budgets compared to 2022
- Harder to comply using prescriptive methods alone
- Increased Role of Energy Modeling
- Greater reliance on performance-based compliance
- Simulation required to meet tighter energy targets
- Battery-Ready & Demand Flexibility Integration
- New emphasis on grid interaction and load shifting
- Buildings designed for future energy storage systems
- Enhanced Indoor Air Quality (IAQ) Requirements
- Improved ventilation standards
- Greater focus on occupant health and comfort
ADU Requirements – What Actually Changed
The 2025 update does not redefine ADU rules but introduces critical performance and system-level changes
- Electrification as a Primary Strategy
- Heat pump HVAC systems strongly favored
- Gas systems becoming less viable for compliance
- Heat Pump Water Heating Emphasis
- Stronger preference for heat pump water heaters
- Higher efficiency expectations
- Battery-Ready & Grid-Responsive Design
- Increased focus on battery integration readiness
- Alignment with grid demand and energy flexibility
- Stricter Performance-Based Compliance
- Lower energy budgets than 2022
- Greater reliance on energy modeling
- Enhanced Indoor Air Quality Standards
- Improved ventilation and airflow requirements
- Higher HVAC Efficiency Expectations
- More stringent system performance requirements
- Better controls and optimized operation required
- Solar Integration Evolving (Not New, but Enhanced)
- Solar PV remains required (from 2022)
- Now aligned with battery-ready and future systems
ADU Key Takeaway
2022 Approach:
- Mixed fuel systems
- Prescriptive compliance possible
- Basic solar integration
2025 Approach:
- Electrification-first design
- Performance modeling required
- Solar + battery-ready systems
- Higher efficiency and IAQ standards
Boiler & Heating System Changes
Key Updates
- Shift away from traditional gas boilers
- Increased preference for heat pump systems
Replacement Impact
- Boiler replacements must meet higher efficiency standards
- Electrification alternatives must be evaluated
Energy Modeling & Compliance Changes
What Changed
- Performance modeling is now more critical than before
- Prescriptive compliance is becoming less sufficient
- Tighter energy budgets require accurate simulation
Updated Workflow Impact
- Earlier integration of energy modeling in design
- Greater coordination between BIM and simulation tools
- Increased importance of compliance documentation accuracy
How AEG Supports Title 24 Compliance & Energy Modeling
At AEG, we support project teams in adapting to these evolving requirements through integrated BIM, energy modeling, and compliance strategies.
Our Approach
- Early-stage energy modeling for optimized design decisions
- BIM-integrated workflows (LOD 100–500)
- Performance-based compliance strategies aligned with 2025 code
What AEG Delivers
- Title 24 compliance documentation
- Energy simulation and modeling
- HVAC optimization aligned with electrification trends
- Support for heat pump and high-efficiency system integration
Value to Clients
- Reduced compliance risk
- Faster approvals
- Optimized building performance
- Future-ready, code-compliant designs
Conclusion
The 2025 Title 24 update represents a clear evolution toward electrification, performance-driven compliance, and high-efficiency building systems. While many base requirements remain unchanged, the level of performance expected has significantly increased, making energy modeling and integrated design essential.
Understanding these changes allows project teams to deliver compliant, efficient, and future-ready buildings.
Reference
https://energycodeace.com/content/2025-title-24-part-6-standards-are-adopted
