Comply or Say Why: DOE rules for firm energy reference standard

Shutterstock/ Viblyphoto
Shutterstock/ Viblyphoto
Published On
Feb 14, 2020

Two years ago, the U.S. Department of Energy ruled the 2016 version of ASHRAE/IES 90.1, “Energy Standard for Buildings except Low-Rise Residential Buildings,” as the national reference standard for commercial building energy codes. All states must have adopted a code at least as this stringent by this month or justify why they cannot comply.

Most states have a commercial building energy code that regulates the designed energy efficiency of nonresidential buildings. While some states, such as California, write their own codes, most are based in whole or in part on a model energy code. The two major model codes are ASHRAE/IES 90.1 and the International Energy Conservation Code. Both are updated every three years.

Compliance with these DOE rulings is typically partial and slow, as the United States remains a mishmash of different codes. According to, as of December 2018, only 10 states had complied with the previous DOE ruling, which recognized the 2013 version of 90.1 as the national energy reference standard. California, Florida, Massachusetts, Nevada and Washington have codes considered more stringent than the 2013 version.

Power—For lighting, the general trend has been steadily decreasing power density and increasing mandatory controls. The 2016 version of 90.1 comparatively contains few changes from its predecessor, though these changes are significant. The biggest is in lighting power density (LPD) allowances. The standard reduces LPD in all but four building types—e.g., 16% in retail buildings (1.06 watt/square feet), 23% in manufacturing facilities (0.9W/square feet) and 27% in warehouses (0.48W/square feet). The additional lighting power allowance for merchandise accent lighting is also reduced for all retail building area types.

Similarly, exterior lighting power allowances are reduced as well. The 2016 standard reduces base-site power allowances by 30–33%, depending on the zone type, which in turn is based on population density. The standard also reduces additional LPD allowances applicable to individual space types, such as parking areas and drives.

These are all big reductions in lighting power. The justification is obviously the rapid advances LED technology has made in efficiency and overall viability during the years prior. The 90.1 Lighting Subcommittee relies on modeling to decide whether a given space type can save energy without compromising lighting quality using cost-effective technology.

Controls—With few exceptions, all lighting must feature various mandatory control strategies. The 2016 version of 90.1 requires that each space have at least one general lighting control device, which can be a manual switch, occupancy sensor or
manual-on timer switch. Manual controls must be capable of light reduction for flexibility and energy savings.

All lighting must be automatically turned off when not in use. Compliant options include scheduling, occupancy sensing and signaling from another building system. Occupancy sensors are specifically required in a broad range of spaces; these must feature an integral on/off switch and have a maximum time delay of 20 minutes.

Additionally, general lighting in areas with sufficient daylight availability must be independently controlled from other general lighting in the same enclosed space. Further controls are required for special lighting types that ensure they are independently controlled from other lighting in the space.

As an incentive to go beyond baseline mandatory controls to save more energy, ASHRAE/IES 90.1-2016 offers another power allowance that can be used anywhere in the building design.

Meanwhile, exterior lighting must be turned off when not in use by employing an astronomical time switch, photosensor or combination of the two. Dusk-to-dawn and other lighting must be reduced after-hours.

All installed controls must be functionally tested with appropriate documentation on the lighting and control system turned over to the owner.

The big 2016 version changes include:

  • The threshold for LPD and automatic shutoff requirements applying to lamp-plus-ballast and one-for-one luminaire replacement retrofits is raised from 10% to 20% of connected lighting load.
  • All nonexempted lighting must be turned off when not in use, including “night lighting” on emergency circuits not required by life/safety statute.
  • Using scheduling or occupancy sensors, dusk-to-dawn exterior lighting must be capable of reducing lighting power by at least 50% (up from 30%) when not being used. Certain parking area luminaires must use an occupancy sensor.
  • Light sensors part of daylight-responsive control systems can be calibrated without a person being present, which recognizes automatically and remotely commissioned sensors.
  • To promote use of luminaire-integrated occupancy sensors, lighting in open-plan offices can automatically turn on to more than 50% of connected power, as long as the control zone is no larger than 600 square feet.

Overall, ASHRAE/IES 90.1-2016 is likely to see greater adoption due to the DOE ruling taking effect this month and further advancing energy efficiency in the design of new commercial buildings and some retrofits. For more information, consult the authority having jurisdiction and the energy code applicable to your area.

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