The ASHRAE/IES 90.1 energy standard provides legal jurisdictions with a model commercial building energy code. The 2013 version is the national energy reference standard recognized by the U.S. Department of Energy. The International Energy Conservation Code recognizes 90.1 as an alternative compliance standard.


Section 9 of 90.1 regulates the energy-efficient design of lighting systems intended for installations as part of new construction, major renovation and some retrofit projects. This section prescribes maximum lighting power density (LPD) allowances by building or space type and mandates installation of a range of lighting controls. It also requires testing and documentation turnover to ensure the system works as installed and the owner can effectively maintain it.


ASHRAE/IES 90.1 2013 adjusted LPD allowances, imposed stringent control requirements, and established a table-based format for determining LPD and control requirements in individual spaces. For example, maximum LPD was reduced 0.9 watts per square foot (W/sq. ft.) to 0.82W/sq. ft. for office buildings. For exterior lighting, power was limited based on lighting zone, which in turn is based on anticipated level of nighttime activity.


Due to quality concerns, the emphasis for saving energy was on lighting controls. The standard shortened occupancy sensor time delay from 30 to 20 minutes, and it required partial-off to 50 percent of design power for spaces such as corridors or stairwells where the lights are periodically not needed but must remain on. The standard also required daylight-responsive controls in primary and secondary daylight zones, with an additional control reduction point for greater lighting flexibility. Finally, the standard imposed more detailed lighting control functional testing requirements.


The biggest change in ASHRAE/IES 90.1 2016 is reduced maximum LPD allowances based on growing maturity and popularity of LED lamps and luminaires. The standard reduces maximum allowable LPDs in all but four applications. For hospitals, it remains 1.05W/sq. ft. For dormitories, movie theaters and museums, it is marginally increased.


In all other building types, however, the standard reduces LPDs, in some cases significantly. For example, maximum allowable LPD is reduced by 23 percent in manufacturing facilities (0.9W/sq. ft.), 16 percent in retail buildings (1.06W/sq. ft.), 7 percent in schools/universities (0.81W/sq. ft.), and 27 percent in warehouses (0.48W/sq. ft.). The additional lighting power allowance for merchandise accent lighting in retail buildings (applicable to the space-by-space compliance method) is also reduced for all retail area types.


Eric Richman, senior research manager, Pacific Northwest National Laboratory, and chair of the 90.1 Lighting Subcommittee, said the LPD allowance adjustments heavily factored LED into this iteration of the standard.


“For a few space models, the fixtures are all LED,” he said. “For many, they are partially LED and, for some, no LED. It just depends on whether LED technology is considered mature, applicable, effective and reasonably cost-effective for that application. The subcommittee found LED to be applicable for many, if not most, fixture applications. In some cases, the available LED products may not have met the grade, so they were not included in the models, or, for some other reason, the existing technology was found to still be superior.”


The 2016 standard reduces exterior lighting power allowances with LED technology in the mix. It reduces base-site power allowances by 30 percent to 350W for Zone 1 (developed land within parks, rural areas, etc.), 33 percent to 400W for Zone 2 (residential, light industrial/commercial, etc.), 33 percent to 500W for Zone 3 (all other areas), and 31 percent to 900W for Zone 4 (high-activity commercial districts in major metro areas). In cases such as parking areas and driveways, the standard further reduced the additional LPD allowances applicable to individual outdoor space types.


Otherwise, ASHRAE/IES 90.1 2016 features a large number of clarifications but few major changes. The standard raises the threshold for LPD and automatic-shutoff requirements to apply to lamp-plus-ballast and one-for-one luminaire replacement retrofits from 10 to 20 percent replacement of the connected lighting load. Lighting in open-plan offices is allowed to automatically turn on to more than 50 percent of connected power as long as the control zone is no larger than 600 square feet, which removes a roadblock to advanced lighting control systems featuring luminaire-integrated sensors.


Light sensor calibration does not require human presence, recognizing auto-commissioning sensors. All lighting must automatically turn off when not in use, including lighting on emergency circuits (including night lighting not required by life/safety code). Dusk-to-dawn exterior lighting must be capable of reducing lighting power by at least 50 percent when not being used based on a schedule or occupancy sensing. Certain parking-area luminaires must use occupancy sensors, with control zoning limited to 1,500W per sensor. At least 75 percent of permanently installed luminaires in high-rise multifamily buildings must have high-efficacy (minimum 55 LPW) lamps installed and operated at a luminaire efficacy of at least 45 LPW.


ASHRAE/IES 90.1 2016 is available for purchase at www.ASHRAE.org.