IECC 2015: What does it mean?
The latest iteration of the International Energy Conservation Code (IECC), IECC 2015, contains dramatic changes to the prescriptive and performance-based criteria that previously defined IECC-compliant lighting and lighting control systems.
The five biggest changes to the lighting control requirements center around further reducing lighting energy used when daylight is available and after business hours, specifying digital lighting controls systems designed to maximize efficiency and minimize waste, and providing documentation that proves the lighting control system performs as intended.
1. Daylighting controls revamped and redefined
Previous versions of IECC allowed daylighting controls to be manual, defined the daylight zone as 15 feet deep, and did not expressly require that daylighting controls be able to turn lights off. That has all changed. IECC 2015 has redefined daylighting controls as daylight-responsive controls, a devices or systems that provide automatic control of electric light levels based on the amount of daylight in a space, and requires these automatic daylight-responsive controls in sidelighted and toplighted areas that contain at least 150W of connected lighting. The daylight zone has also been redefined to more directly correspond to the specific height and width of the fenestration on the project. In addition, the new code redirects the way in which sidelighted daylight zones should be controlled; with some exceptions, zones facing different cardinal directions (N, E, S, W) should now be controlled independently.
2. Continuous dimming now required in certain daylight spaces
IECC 2015 identifies specific spaces where automatic daylight-responsive controls must be paired with continuous dimming instead of allowing step dimming or other ways to achieve light level reduction in a space. In offices, classrooms, laboratories and library reading rooms, daylight-responsive controls shall dim continuously from full light output to less than 15 percent. This design requirement is intended to allow lighting systems in these areas to maximize energy savings, while daylight is present, without causing noticeable and distracting changes in the lighting environment throughout the day.
3. Reduce exterior lights at night
For some time, energy standards have required automatic controls to ensure that interior lights are off at night when the business is closed and the building is empty. Now, IECC 2015 is including exterior lighting in those after-hours and unoccupied energy-saving efforts. Exterior lighting that is not façade or landscape lighting must automatically reduce its peak power by at least 30 percent one hour after business closing to one hour before business opening, or when no activity has been detected in the area for longer than 15 minutes.
4. Use a digital lighting control system to satisfy additional energy efficiency options
IECC 2015 modified and expanded the compliance options available to meet mandatory Section C406 Additional Energy Package Options. The expanded list now includes two choices focused on lighting efficiency: designing a system with lower lighting power allowances, or specifying a digital lighting control system that will provide continuous dimming and individual addressability of the lamps and fixtures. The digital lighting control system offers designers a viable compliance alternative to meeting increasingly strict lighting power allowances.
5. New commissioning documents deadline
IECC 2015 requires that construction documents certifying that the installed lighting controls meet documented performance criteria are to be provided to the building owner within 90 days from the date of receipt of the certificate of occupancy.
Note: for project-specific requirements and interpretation of the changes to lighting and lighting controls requirements within the code, please consult IECC 2015 and the building authority with jurisdiction.
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