Lighting Controls Association (LCA) Education Director and LightNOW Founder, Craig DiLouie recently published an article, Deep Dive Into the Lighting Control Requirements of the 2024 IECC. The article provides a comprehensive overview of the lighting control requirements introduced in the 2024 International Energy Conservation Code (IECC), focusing on commercial buildings. The IECC, updated every three years, is widely adopted across the United States as a model energy code for both commercial and residential construction, though states and jurisdictions may adopt different versions or alternative standards such as ANSI/ASHRAE/IES 90.1.
The U.S. lacks a single national energy code, resulting in a patchwork of state and local requirements. The Department of Energy (DOE) recognizes ANSI/ASHRAE/IES 90.1 as the national reference standard, and states must adopt the 2022 revision or an equivalent by 2026 to receive enforcement funding. The IECC is commonly adopted, and its 2024 revision is generally considered equivalent to 90.1-2022. Designers must confirm the applicable code and version for each project due to this variability.
The 2024 IECC offers two compliance paths: prescriptive (specific requirements and limitations) and performance-based (building energy modeling). The prescriptive path includes mandatory lighting control provisions for nearly all new construction and many alterations, covering both interior and exterior lighting. The code’s central aim is to minimize unnecessary energy consumption by ensuring lighting is reduced or turned off when not needed, using occupancy, scheduling, or ambient light as triggers. Manual controls for occupant convenience and zoning for independent lighting control are also mandated, with detailed exemptions specified in the code.
Key changes in the 2024 IECC include:
- Lower allowable lighting power for both interior and exterior applications.
- Revised thresholds for when alterations must comply.
- Removal of the luminaire-level lighting controls (LLLC) as a formal compliance path.
- New requirement for continuous dimming for light reduction controls.
- Changes to enhanced energy efficiency options, including the elimination of digital controls and the addition of demand-responsive controls.
- Requirement for functional testing of certain automatic controls.
Manual controls must be accessible and allow occupants to control general lighting. Occupant sensors are required in many spaces, often set to partial-on (up to 50% power) or manual-on modes, with manual overrides for full-on or off. In spaces not requiring sensors, time-switch controls can be used, with override capabilities and limitations on the area and duration of lighting that can be manually activated.
The 2024 code now mandates continuous dimming (rather than bilevel switching) for general lighting in many spaces, allowing dimming from full output down to 10% or less, plus off. Automatic shutoff controls—either occupant sensors or time-switches—are required to turn off or reduce lighting when areas are unoccupied. Specific requirements apply to spaces like warehouses, open-plan offices, corridors, and parking garages, with detailed rules for sensor placement, control zones, and response times.
Daylight-responsive controls are required in primary and secondary sidelit and toplit daylight zones, with reduced wattage thresholds in the 2024 revision. These controls must provide continuous dimming from 100% down to 15% or less and be independently calibrated by authorized personnel. Exemptions exist for smaller enclosed offices and certain other spaces.
Special requirements apply to display lighting, supplemental task lighting, and nonvisual applications like plant growth, often requiring independent time-switch or occupant sensor controls. Interior parking garages must reduce lighting power in response to vacancy and daylight. Sleeping and dwelling units in hotels and similar facilities must have automatic shutoff for lighting and switched receptacles, with specific rules for override and manual control.
At least half of all permanently installed receptacles in specific areas must be automatically controlled, with clear labeling and uniform distribution. Control methods include time-switches, occupant sensors, or signals from other systems. Exterior lighting controls are also addressed.
Overall, the 2024 IECC introduces more stringent lighting control requirements, emphasizing automation, occupant convenience, and energy efficiency across a wide range of commercial building applications.
DiLouie’s complete LCA article can be found here.
Image: IECC
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