Introduction

California Senate Bill 655 (SB-655), authored by Senator Henry Stern, is a crucial response to one of the most urgent climate-related health risks: extreme heat.  Signed into Law on 10 October 2025, SB-655 establishes a state policy requiring all residential dwelling units to maintain a safe maximum indoor temperature.  This legislation marks a significant shift in housing standards, prioritizing heat safety alongside existing cold-weather protections.  

Why SB-655 Matters

Extreme heat is now the leading weather-related cause of death in the U.S., surpassing floods and hurricanes.  California’s vulnerability is amplified by:

• Frequent heat waves: A 10-day heat wave in September 2022 caused 395 excess deaths statewide.
• Climate projections indicate that urban heat-related deaths could double or triple by 2050.
• Equity concerns: Lower-income communities often experience higher indoor temperatures due to inadequate insulation and a lack of access to cooling systems.

Key Provisions of SB-655

·         State Policy Declaration

o   All dwelling units must be able to attain and maintain a safe maximum indoor temperature.

·         Agency Responsibilities

o   Starting 1 January 2027, agencies such as the Department of Housing and Community Development (HCD), Energy Commission, and Public Utilities Commission must integrate this policy into:

§  Regulations

§  Grant criteria

§  Housing programs

·         Building Standards

o   The California Building Standards Commission must adopt strategies—both passive and active—such as:

§  Mechanical ventilation

§  Natural ventilation

§  Shading and cooling techniques

o   Target: Maximum indoor temperature of 82°F for newly constructed residential units by the next triennial code update after 1 January 2026.

·         Limitations

o   The bill does not mandate the state to fund cooling infrastructure or create new obligations beyond existing programs.

Legislative Journey

• Introduced: 20 February 2025
• Passed Senate: 4 June 2025 (39–0)
• Passed Assembly: 9 September 2025 (66–5)
• Signed into Law: 10 October 2025 (Chapter 522, Statutes of 2025)

Implications

For Homebuilders

• New construction must incorporate heat mitigation strategies.
• Compliance will influence design, materials, and HVAC systems.

Compliance Checklist for Developers

✅ Passive Cooling First

• High-performance insulation
• Reflective roofing
• Low-emissivity windows
• Cross-ventilation design

✅ Active Cooling

• Energy-efficient HVAC sized for heat extremes
• Smart thermostats and zoned cooling

✅ Shading Strategies

• Overhangs, awnings, exterior shading
• Landscaping for natural cooling

✅ Future-Proof Your Design

• Meet or exceed the 82°F standard now
• Document compliance for inspections

✅ Tap Incentives

• Monitor grants for heat-resilient construction
• Align with energy efficiency programs

For State Agencies

• Must align housing and climate programs with the new policy.
• Potential adjustments in grant funding priorities.

For Residents

• Long-term goal: safer homes during heat waves.
• Particularly critical for mobile homes and older housing stock, which often lack adequate cooling.

Challenges and Criticism

• Cost Concerns: Builders Warn of Increased Construction Costs.
• Implementation Timeline: Agencies have until 2027 to integrate standards, raising questions about interim protections.
• Equity Issues: While the bill sets policy, it does not guarantee financial assistance for retrofitting older homes.

Conclusion

SB-655 is a landmark step toward enhancing climate resilience and protecting public health in California.  By codifying a safe indoor temperature standard, the state acknowledges the deadly Impact of extreme heat and begins laying the groundwork for safer housing.  This legislation not only addresses a pressing issue but also paves the way for a more resilient and healthier future for all Californians.  However, its success will depend on effective implementation, funding strategies, and support for vulnerable communities.