The ANSI/ASHRAE/IES 90.1 energy standard provides a model energy code to jurisdictions interested in regulating the energy-efficient design of commercial buildings. The International Energy Conservation Code (IECC) recognizes 90.1 as an alternative compliance standard. ASHRAE recently published the 2016 version, which supersedes the 2013 version.
The U.S. Department of Energy (DOE) recognizes the 2013 version as the national energy reference standard. Starting October 2016, all states must have an energy code in place at least as stringent as 90.1-2013 or justify why they cannot comply. A look at EnergyCodes.gov reveals 13 states are currently in compliance.
Section 9 covers interior and exterior lighting systems installed as part of new construction, major renovation and some retrofit projects. We can categorize its provisions as either mandatory or prescriptive. Mandatory provisions primarily cover lighting controls, functional testing and documentation. Prescriptive provisions primarily cover maximum lighting power density (LPD, in W/sq.ft.) allowances by building or space type.
Changes in 2013
Before we look at what’s new in the 2016 version, let’s review what changed in the previous version. ASHRAE/IES 90.1-2013 adjusted LPD allowances, established more stringent control requirements, and created a table-based formula for determining LPD and control requirements in individual spaces. For exterior lighting, lighting power allowances are based on lighting zones in turn based on anticipated nighttime activity level.
Due to concerns about the effect further pressing lighting power allowances could have on lighting quality, the code’s writers focused on energy-saving lighting controls instead of squeezing further reductions out of LPD. The 90.1-2013 standard:
• Shortens occupancy-sensor time delay from 30 to 20 minutes.
• Requires partial-OFF to 50% of design power for spaces where the lights are intermittently used but have to stay ON, such as corridors and stairwells.
• Requires daylight-responsive controls in secondary as well as primary daylight zones, with an additional control reduction point for greater flexibility in reduction.
• Imposes more detailed lighting control functional testing requirements.
Changes in 2016
ASHRAE/IES 90.1-2016 contains few modifications, but they are significant. The biggest change is in interior and exterior LPD allowances as advances in LED technology put significant LPD reductions back on the table. The standard reduces maximum allowable LPD in all but four building types (hospitals, dormitories, motion picture theaters and museums). LPD is reduced in all other building types.
For example, the standard reduces LPD by 23% in manufacturing facilities (0.9W/sq.ft.), 16% in retail buildings (1.06W/sq.ft.) and 27% 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.
The 90.1 Lighting Subcommittee relies on modeling to determine whether a given space type could save energy without compromising lighting quality using cost-effective, commercially available lighting technology. As noted, for the 2016 standard, the Lighting Subcommittee relied heavily on LED technology: all LED in some space models, others a mix of LED and conventional technology, some only conventional technology as LED was not seen as making the grade yet.
The 2016 standard reduces exterior lighting power allowances as well, again based on modeling heavy on use of LED technology. It reduces base-site power allowances by 30% for Zone 1 (developed land within parks, rural areas, etc.), 33% for Zone 2 (residential, light industrial/commercial, etc.), 33% for Zone 3 (all other areas), and 31% for Zone 4 (high-activity commercial districts in major metro areas). In some cases, such as parking areas and drives, the standard further reduces additional LPD allowances applicable to individual space types.
Otherwise, ASHRAE/IES 90.1-2016 contains clarifications but otherwise few major changes. For example, the standard:
• Raises the threshold for LPD and automatic shutoff requirements applying to lamp-plus-ballast and one-for-one luminaire replacement retrofits from 10% to 20% of the connected lighting load.
• Allows lighting in open-plan offices to automatically turn ON to more than 50% of connected power as long as the control zone is no larger than 600 sq.ft. This provision was inserted to remove an impediment to advanced control systems using luminaire-integrated sensors.
• Allows light sensor calibration in daylight-responsive control systems to occur without a person being present. This change recognizes the utility of auto-commissioning sensors.
• Requires all lighting be automatically turned OFF when not in use, including “night lighting” on emergency circuits not required by life/safety statute.
• Requires dusk-to-dawn exterior lighting be capable of reducing lighting power by at least 50% when not being used based either on a schedule or occupancy sensing. This is an increase from 30% in the 2013 version of the standard. Further, certain parking area luminaires must use an occupancy sensor, with control zoning restricted to 1500W per sensor.
• Requires at least 75% of permanently installed luminaires in dwelling units in high-rise multifamily buildings be high efficacy (at least 45 lumens/W) and feature high-efficacy (at least 55 lumens/W) lamps.
Energy codes have made a big impact on energy efficiency in new buildings and product development while having a halo effect on existing construction. DOE continues to update the national energy reference standard to promote maximum energy savings in complying states. As DOE recognizes 90.1 as the national energy reference standard, it is likely that 90.1-2016 will become the new national energy reference standard at some point after 2019.
Overall, the 2016 version of 90.1 significantly reduces lighting power allowances, indicating the energy-saving potential and widespread utility of LED technology. It ensures night lighting not required by statute be turned OFF to eliminate energy waste. It also contains significant clarifications to remove potential roadblocks to adoption of intelligent lighting controls. The 2019 version is expected to show even greater LPD reductions as the technology continues to mature and may contain further provisions encouraging networked controls.
ASHRAE/IES 90.1-2016 is available for purchase at ASHRAE.org. Consult the authority having jurisdiction for interpretations.