Smarter Buildings Ahead: Key Updates to ASHRAE 90.1-2025 and 2024 IECC

Energy codes are tightening across the U.S. as part of aggressive decarbonization goals. The latest updates to ASHRAE 90.1-2025 and 2024 International Energy Conservation Code (IECC) highlight advanced lighting controls and submetering as essential strategies for reducing energy consumption and improving accountability. For designers, contractors, and facility managers, these changes represent both compliance challenges and sustainability opportunities.

Lighting Control Updates

ASHRAE 90.1-2025 introduces expanded lighting control requirements aimed at deeper energy savings across building types.

  • More granular zoning is emphasized, grouping luminaires more effectively with occupancy and daylight sensors
  • Advanced daylighting integration expands daylight-responsive controls, requiring dimming or shutoff near windows and skylights
  • Stricter automatic shutoff provisions are included, with clearer guidance on sensor placement and overrides

The standard also encourages lighting systems to integrate more efficiently with HVAC and building controls, improving overall energy efficiency while maintaining occupant comfort.

2024 IECC introduces stricter requirements for lighting systems, focusing on efficiency, control, and demand response.

  •  Automatic shutoff: Now applies to nearly all luminaires and switched receptacles
  • Dimming standards: Spaces requiring dimming must allow continuous adjustment down to 10% of full power, with full shutoff capability
  • Demand response: Lighting systems must be able to dim automatically when signals are received from utilities

Occupancy sensors are also expanded to cover more spaces:

  • Data centers
  • Telemedicine rooms
  • Warehouses

In hotels and multifamily units, lights and receptacles must shut off automatically within 20 minutes of vacancy.

Finally, stricter lighting power allowances reduce watts per square foot across building types, driving efficiency even further.

Submetering Requirements

The upcoming ASHRAE 90.1-2025 and 2024 IECC both introduce strengthened submetering requirements, mandating that building owners track energy use by end-use categories such as HVAC, lighting, plug loads, and service water heating to improve accountability and efficiency.

ASHRAE 90.1-2025

Section 8.4.3 mandates end-use metering for new construction and major renovations. Submeters must provide hourly data, store at least 36 months of history, and integrate with building management systems. Electricity, gas, thermal energy, and water must be separately metered where applicable.

2024 IECC

Submeters are now required for HVAC, lighting, plug loads, and other major systems, with no more than 5% of design load excluded. Systems must capture total energy across categories for accurate reporting.

Conclusion – Implications for Industry 

The alignment of ASHRAE 90.1 and IECC makes one thing clear: smarter lighting controls and comprehensive submetering requirements are now essential for future-proof buildings. These updates not only cut energy use but also improve transparency and accountability. By adopting these requirements, stakeholders can stay compliant while gaining long-term efficiency benefits and positioning themselves as leaders in sustainability. To learn more, visit Leviton.com/energycodes.