Last year, the International Code Council published the 2015 International Energy Conservation Code (IECC), a model energy code that states and other jurisdictions can use in whole or part as their energy code. Today, many states base their commercial building energy code on the IECC.


The Department of Energy requires states to adopt a code at least as stringent as ASHRAE/IES 90.1 2013 by September 2016. Since the 2015 IECC would be equivalent, it will likely see significant adoption.


The 2015 IECC follows the 2012 version with more restrictive lighting-power allowances. The Building Area Method lighting-power allowances are roughly in alignment with the ASHRAE/IES 90.1 2013 energy standard. Power allowances were adjusted down from 0.9 watts per square foot (W/sq.ft.) to 0.82W/sq.ft. for offices, 1.4–1.26 for retail, 1.2–0.87 for schools/universities, and 1.0–0.9 for healthcare clinics. Warehouses saw an increase from 0.6–0.66W/sq.ft.


The most extensive changes in the IECC 2015 are in lighting controls. Consult the code and the authority having jurisdiction for specific requirements and interpretation related to your project.


Interior automatic lighting shutoff


With few exceptions, interior lighting must be turned off when not in use. Occupancy or time-switch control can be used.


Occupancy sensors are required in a list of specific applications, including classrooms, private offices and warehouses. The sensor must be ­manual-on or auto-on to maximum 50 percent of lighting power (except in warehouses), must turn lights off within 30 minutes of vacancy, and give occupants manual-off capability. In warehouses, the sensor must reduce lighting power by at least 50 percent after the aisle is vacated, be zoned to a single aisle, and must not control lighting outside the aisle.


Time-switch controls must be installed where occupancy sensors are not. The control must feature a minimum seven-day clock, backup capability in case of a power interruption, and holiday programming. A manual override switch must be provided.


Manual override


The manual override switch allows occupants to use their local lighting, with the override area limited to 5,000 sq.ft. and time limited to two hours (which may be renewed by resetting the switch). It also provides basic manual control.


Some malls and industrial buildings allow up to 20,000 sq.ft. as the override control zone, and the time limit is extendable as long as the override switch is a captive key device.


The switch must be readily accessible with the controlled lighting in view. The switch may be installed remotely if it identifies the location and status of the controlled lighting. It must be capable of light-reduction control, providing the ability to reduce lighting power by at least 50 percent in a reasonably uniform illumination pattern, using multilevel switching or continuous or step-dimming.


Daylight-responsive controls


Automatic daylight-responsive lighting controls are required in applicable sidelighted (e.g., windowed) and toplighted (e.g., skylighted) daylight zones. The automatic controls must be capable of turning the lights off. In offices, classrooms, laboratories and library reading rooms, they must be capable of continuous dimming to 15 percent or less of full light output. The controls must be capable of being calibrated, with ready access, where installed.


Special applications


IECC 2015 identifies special applications and presents requirements for lighting controls. For example, display and accent lighting must be controlled independently, and supplemental task lighting must be controlled by an integral control device or accessible wall-mounted control.


Exterior lighting control


All lighting must be capable of being turned off automatically in response to daylight (photosensor). Building facade and landscape lighting must also be capable of turning off at a set time after hours (astronomical time switch). Other lighting must be reduced by at least 30 percent after hours in response to a time event or occupancy (occupancy sensor).


More energy-efficiency options


IECC 2015 requires the designer to optimize energy efficiency. One option is to comply with lighting-power allowances adjusted by a factor of 0.90. The second is to install a digital lighting control system capable of continuous dimming, individual luminaire addressability, load shedding, reconfiguration, and occupant control of overhead lighting in open offices.


Commissioning


IECC 2015 requires commissioning of the building’s power and lighting systems. Documentation requirements include a lighting and control narrative, operating and maintenance manuals, submittal data indicating all selected options for lighting and controls, and an inspection and recalibration schedule for lighting controls. The IECC also requires functional testing for automatic lighting control, and it has specific requirements for each control type.


The IECC has evolved in three major directions—greater alignment with 90.1, lower lighting-power allowances and broader control requirements, all of which increased the complexity of lighting. For more information, consult the IECC 2015.