Complying With Lighting Standards: Major changes in new 90.1 and IECC regulations

By Craig DiLouie | Aug 14, 2023
On July 28, 2023, the 2019 version of the ANSI/ASHRAE/IES 90.1 energy standard took effect as the new national energy reference standard.




On July 28, 2023, the 2019 version of the ANSI/ASHRAE/IES 90.1 energy standard took effect as the new national energy reference standard. By that date, all states were required to have an energy code at least as stringent as the standard, enabling them to qualify for code implementation funding.

Commercial building energy codes regulate the design energy efficiency of new buildings and renovations. States may write their own code or, more commonly, adopt a model such as 90.1 or the International Energy Conservation Code (IECC). Some states do not have a statewide code, though adoption may occur in various jurisdictions.

Based on previous adoptions, about half the states are expected to eventually gain compliance over time. A majority of those that comply will likely adopt the 2021 IECC, which recognizes 90.1 as an alternative compliance standard.

In terms of lighting, there are many similarities between 90.1-2019 and the 2021 IECC, which constantly seek alignment. At the core, these lighting sections prescribe maximum lighting power allowances and mandate various measures, predominantly lighting controls. Regarding controls, generally, all lighting must be automatically turned off or reduced when it’s not needed, with supplementary manual control.

As the Department of Energy ruling means more stringent energy codes may be coming, let’s take a look at major lighting changes in the 2019 version of 90.1 versus the 2016 version, and the 2021 IECC versus 2018. This information is provided for general educational purposes; for more information, consult the code or the authority having jurisdiction.


The 2019 version reduces many interior lighting power allowances, sharpens some mandatory control requirements and offers a new simplified compliance method for office, school and retail buildings.

Lighting power: The standard prescribes maximum interior lighting power allowances for buildings and spaces, depending on the chosen compliance path. While some building types saw an increase in power allowance, the rest saw reductions, including roughly 10% for schools/universities, hospitals and manufacturing, and roughly 20% for office and retail.

The 2019 version also created a new compliance path for common building types—office, retail and schools—under certain conditions. A table identifies lighting applications with power allowances and related lighting control requirements. This is an effort to simplify compliance.

Lighting controls: The 2019 version revised requirements for parking garages and daylight-responsive control. For parking garages, lighting power must be reduced by at least 50% when no occupancy activity is detected for 10 minutes. For daylight-responsive control, when responding to daylight, the photocontrol must reduce lighting power by at least 80% using continuous dimming. If lighting power is already being reduced by a partial-off control, the daylight-responsive control can adjust but may not increase power above the set partial-off level.

2021 IECC

The 2021 version generally reduces lighting power allowances and adds daylight-­responsive control to secondary daylight zones in addition to new requirements for parking garage controls. What’s more, automatic power receptacle control is now required in various spaces.

Lighting power: Like 90.1-2019, the 2021 IECC reduced interior lighting power allowances in many building types.

Lighting controls: The 2021 IECC added corridors to the space types requiring occupancy sensors, which must reduce lighting power by at least 50% within 20 minutes of detecting vacancy. General lighting in secondary daylight zones (areas adjacent to primary daylight zones) now requires daylight-responsive control in addition to primary daylight zones (areas adjacent to sidelighting or under toplighting fenestrations). Occupancy sensing or time-switch control is required in parking garages. Certain outdoor dusk-to-dawn parking lot luminaires must be controlled by an occupancy sensor that reduces power.

Power receptacle control: A significant change is that automatic plug load control is required in certain applications such as enclosed offices, workstations and classrooms. A minimum of 50% of all permanently installed 125V, 15A and 20A receptacles must be controlled, along with other requirements.

A higher standard

In terms of lighting, the two big trends in commercial building energy codes over the past 20-plus years have been shrinking lighting power allowances and increasing lighting control requirements. This recognizes the viability and maturity of LED lighting and the utility of detailed lighting control strategies. As this also leads to increasing complexity, codes and standards writers update them with important clarifications and attempt to simplify compliance.

As for the future, we are likely to see codes continue to evolve even as they finally close in on their full potential for generating energy efficiency, at least in lighting. For example, some jurisdictions are experimenting with codes that regulate energy consumption in existing buildings or seek to limit carbon emissions.

shutterstock / l i g h t p o e t

About The Author

DiLouie, L.C. is a journalist and educator specializing in the lighting industry. Learn more at and





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