“This code shall regulate the design and construction of buildings for the use and conservation of energy over the life of each building.”
The IECC is not a code in itself but instead a template that states and other jurisdictions may use this model in whole or in part for their own energy codes. First published in 1998, the IECC was updated in 2000, 2003, 2006, 2009, 2012 and 2015.
The ASHRAE/IES 90.1 energy standard is the national energy reference standard recognized by the Department of Energy. However, IECC is broadly adopted by the states. IECC recognizes 90.1 as an alternative compliance option, though the 2009 and later versions of IECC require compliance with either IECC or 90.1 in its entirety, not by section.
As of December 2014, 15 states had in place a commercial building energy code at least as stringent as ASHRAE/IES 90.1-2010 and IECC 2012, and 27 had in place a code at least as stringent as ASHRAE/IES 90.1-2007 and IECC 2009. None had yet adopted IECC 2015; adoption takes time. A rough analysis of current adoption showed 26 states that have adopted some version of IECC, nine 90.1, nine a state-specific code, and six no statewide code.
IECC applies to new construction and renovations in existing buildings. If 50% or more of the luminaires are replaced, the new lighting must comply with all applicable lighting and control requirements in the current code. Lighting maintenance activities, including replacement of lamps and ballasts in existing luminaires, are considered repairs and must maintain the design completed under the current edition of the code under which it was installed.
The 2015 IECC features more restrictive lighting power allowances. A comparative review of the Building Area Method lighting power allowances show them to be roughly in alignment with the ASHRAE/IES 90.1-2013 energy standard. For example, the power allowance was adjusted down from 0.9W/sq.ft. to 0.82 for office, 1.4 to 1.26 for retail, 1.2 to 0.87 for school/university, and 1.0 to 0.9 for healthcare clinic. Warehouse saw an increase from 0.6 to 0.66W/sq.ft.
Beyond adjustments to the lighting power allowances using both the Building Area and Space by Space compliance methods, the most notable changes in the 2015 version are in its mandatory controls requirements and a new control-related advanced energy efficiency option. In fact, the entire lighting control section of the code has been revised.
This special report by the Lighting Controls Association describes the commercial building lighting control requirements of IECC 2015, detailed primarily in Section C405.2.
Note that for each feature described, exceptions may apply. Consult IECC 2015 and the authority having jurisdiction for specific requirements and interpretation relevant to your project.
Interior lighting: automatic shutoff
With few exceptions, interior lighting must be automatically turned OFF when it is not in use. The designer is required to either use occupancy or time-switch control.
Occupancy sensors: Occupancy sensors are required in classrooms, private offices, restrooms, janitorial closets, warehouses and other spaces listed in the code. While required in these spaces, they may be used in other spaces not listed.
If the space is any type of space other than a warehouse, the occupancy sensor must be manual-ON or auto-ON-to-maximum-50% of lighting power, with notable exceptions allowing full auto-ON operation. The sensor must turn the lights OFF automatically within 30 minutes of the space being vacated, with occupants provided manual-OFF capability.
In warehouses, the occupancy sensor must reduce lighting power by at least 50% after the aisle is vacated. Each aisle must be controlled independently. Occupancy sensors controlling aisle lighting must not control lighting outside the space within the aisle.
Time-switch controls: Where occupancy sensors are not installed, a time-switch control must be installed. These controls automatically turn the lights OFF based on a schedule.
The time-switch control must feature 1) a minimum seven-day clock, 2) backup capability preventing loss of programming and settings for at least 10 hours if power is interrupted, and 3) ability to automatically turn the lighting OFF for 24+ hours (“holiday” shutoff) before resuming normal operation.
Further, the time-switch control must feature a switch that allows users to override the automatic shutoff function, described below.
Interior lighting: manual controls
Manual control functionality must be provided everywhere automatic controls are installed and in some spaces where automatic control does not apply.
In occupancy sensor installations, the sensor must be manual-ON or auto-ON-to-maximum-50% of lighting power, with occupants being given the capability of achieving full output with a switch. Occupants must also be able to turn the controlled lighting OFF manually.
Time-switch controls must be installed with manual override switches that also provide light reduction control capability.
Override switches: The override switch allows occupants to continue to use the space after scheduled ON hours. The override is limited to two hours. If the occupant continues to require the lighting after that, he or she would have to reactivate the override at the switch. To minimize energy waste, the control zone area for each override is limited to 5,000 sq.ft.
Malls, arcades, auditoriums, single-tenant retail spaces, arenas and industrial buildings are treated differently. The override can be longer than two hours as long as the override switch is a captive key device. Additionally, the override control zone is limited to a larger 20,000 sq.ft.
All override switches must be located so that they are readily accessible to occupants with the controlled lighting being visible. Alternately, the switch may be installed remotely if needed as long as it identifies the lighted area and indicates the controlled lighting’s status.
Light-reduction control: The override switch must be capable of light-reduction control, giving the occupant the ability to reduce lighting power by at least 50% in a reasonably uniform illumination pattern.
Lighting reduction may be implemented by multilevel switching (alternate lamps, luminaires or luminaire rows), continuous dimming or step dimming each lamp, or some method approved by the AHJ.
As with many code provisions, some exceptions apply, though a notable exception is spaces in daylight zones featuring daylight-responsive controls.
Interior lighting: daylight-responsive controls
Automatic daylight-responsive (daylight harvesting) lighting controls are required in the building’s applicable sidelighted (e.g., windowed) and toplighted (e.g., skylighted) daylight zones if the general lighting load in the zone is >150W.
Exceptions apply, with a notable exception for sidelighted daylight zones being general lighting used for a recognized special application, as described in the next section.
General control function: Where automatic daylight-responsive controls are required, the general lighting in toplighted daylight zones must be controlled separately from general lighting in sidelighted daylight zones. Up to 150W of lighting in contiguous daylight zones (adjoining daylight zones facing different cardinal directions—i.e., within 45 degrees of due N, S, E, W) may be controlled by the same daylight-responsive control. All other lighting in daylight zones facing different cardinal directions must be controlled independently.
The automatic controls must be capable of being calibrated where installed, with the means of calibration readily accessible to authorized personnel.
Otherwise, the designer has broad latitude in deciding how the lighting should be controlled in response to daylight availability. At a minimum, the controls must feature automatic response to daylight. They must be capable of turning the lights completely OFF. In offices, classrooms, laboratories and library reading rooms, the controls must also be capable of continuous dimming to 15% or less of full light output.
Daylight zones: The IECC defines the daylight zone adjacent to vertical fenestration and under toplighting using text and graphics. Consult the IECC for more information.
Interior lighting: controls for specific applications
IECC 2015 identifies special applications for lighting controls and presents requirements.
Display and accent, display case, non-visual (e.g., food warming) and lighting for sale or for demonstration must be controlled by a dedicated control that operates independently of other lighting within the room/space.
Supplemental task lighting, both portable and permanently installed, must be controlled by an integral control device or a readily accessible wall-mounted control device.
In hotel and motel sleeping rooms and guest suites, a master control device must be provided that automatically turns OFF all installed lighting and switched receptacles (unless controlled by a captive key system) within 20 minutes of all occupants leaving the room.
Walk-in coolers and freezers must feature lamping operating at an efficacy of at least 40 lumens/W, including ballast losses, or an occupancy sensor that turns the lights OFF automatically within 15 minutes of the cooler or freezer being unoccupied (C403.2.16).
Refrigerated display cases built or assembled on site must feature lighting that is automatically controlled by one of two options (C403.2.17). The first is a time switch that turns the lights OFF during non-business hours, with a time override of up to one hour being permitted. The second is an occupancy sensor that reduces lighting power by at least 50% within three minutes of the space being vacated.
Exterior lighting control
With notable exceptions, all exterior lighting must be turned OFF automatically in response to daylight. This would entail the use of a photosensor.
Building facade and landscape lighting must automatically turn OFF both in response to daylight and at a set time during the evening after normal business hours. This would entail the use of an astronomical time-switch.
Lighting that is not facade and landscape lighting must be reduced during the evening after normal business hours. Lighting power must be reduced by at least 30% 1) from one hour after business closing to one hour before business opening, but not later than midnight to 6AM (entailing use of an astronomical time switch), or 2) when a lack of activity has been detected in the area for longer than 15 minutes (entailing use of an occupancy sensor).
If a time switch is used, it must be capable of retaining its programming and time setting during a power interruption for at least 10 hours.
Additional energy efficiency options
A major change in the 2012 IECC was Section C406, Additional Efficiency Package Options, which required the building to optimize either HVAC or lighting efficiency or produce renewable energy onsite. The 2015 version expands these options to include a lighting controls option. Therefore, if the designer chooses to optimize lighting efficiency, he or she has two options. He or she can either comply with the lighting power allowances adjusted by a factor of 0.90, or specify installation of a digital lighting control system.
The digital lighting control system must provide all of the functionality required in C405.2.2 (described above) with additional requirements:
Luminaires must be capable of continuous dimming and individual addressability. If individual addressability is not available for the given luminaire type, control zoning is limited to a maximum of four luminaires.
In daylight zones, control zones are limited to a maximum of eight luminaires.
The control system must provide reconfiguration (based on digital addressability, and including occupancy sensors), load shedding and individual user control of overhead general lighting in open office spaces. The construction documents must include a specification outlining each of these functions while also including a sequence of operations.
The lighting controls must be functionally tested in accordance with Section C408.3.
Commissioning, covered in C408, is required for the building’s mechanical and electrical lighting and power systems, with a broad list of requirements covering the commissioning plan and reporting to documentation requirements. The documentation requirements include a lighting and control narrative, operating and maintenance manuals, submittal data indicating all selected options for lighting and controls, and a schedule for inspecting and recalibrating lighting controls.
Along with the luminaire schedule with wattage, a lighting control narrative is also required as part of the construction documents to be submitted with each application for a permit (C103.1).
Functional testing for automatic lighting controls is required and covered specifically in C408.3. The end result is the designer demonstrating that the lighting control systems have been tested to ensure they operate in accordance with construction documents and manufacturer instructions. The construction documents must specify that the building owner will be given, within 90 days from the date of receipt of certificate of occupancy, written certification that the lighting controls meet documented performance criteria.
Occupancy sensors: For projects where fewer than eight occupancy sensors are installed, each must be tested. If more than seven are installed, at least 10% (and at least one) will be tested for each unique combination of sensor type and space geometry. If 30% or more fail the acceptance criteria, all remaining identical combinations must be tested. Verify:
1. Proper location and aiming.
2. Correction operation where the sensors include status indicators.
3. The lights turn ON to the permitted level when the space becomes occupied (if auto-ON).
4. The lights turn ON only when manually activated (if manual-ON).
5. False-ON triggering does not occur by movement in adjacent areas or from HVAC operation.
Time-switch controls: Verify:
1. The time-switch control is programmed with accurate weekday, weekend and holiday schedules.
2. The time switch includes the correct time and date.
3. Any battery backup is installed and energized.
4. The override is set to no longer than two hours.
5. Simulating an occupied condition, that all lights can be turned ON/OFF by their local manual switch, and that the switch only operates the local lighting.
6. Simulating an unoccupied condition, that the controlled lighting turns OFF, and that the manual override allows only local lighting to turn ON and remain ON until the next time sweep occurs within two hours.
Additional testing may be required by the AHJ. The owner must be given documentation indicating the programming (including weekday, weekend and holiday schedules) and all other settings.
Daylight-responsive lighting controls: Verify:
1. Proper location of all control devices.
2. Calibration of devices (with calibration adjustment being readily accessible only to authorized personnel) with accurate set-points and threshold light levels.
3. Lighting adjusts to light level set-points in response to daylight.
Like 90.1, the IECC has come a long way in the past 10 years, evolving from requiring automatic shutoff and bilevel switching to detailed requirements for occupancy sensing, exterior control, daylight harvesting, commissioning and encouraged use of digital addressable lighting control systems. For more information, purchase the IECC 2015 here or from any other convenient seller.