Illinois Energy Conservation Code Training and Support Program
2012 IECC - Frequently Asked Questions - 2012 IECC

V. BUILDING LIGHTING SYSTEMS

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Q: With respect to Lighting Alterations, Section C101.4.3, Exception 7 allows alterations that replace less than 50 percent of the luminaires in a space, provided that such alterations do not increase the installed interior lighting power. There are a variety of ways that this exception can be interpreted, please explain?

A: If the scope of the work includes lighting and other IECC regulated systems, and less than 50% of the luminaires are replaced, the lighting alterations (alone) are exempt, provided that the lighting alterations (alone) do not increase interior connected lighting power beyond the former level of connected lighting power for the altered/affected spaces.

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Q:  Is daylight harvesting and thereby, daylight zone control required by the 2012 IECC?

A: Yes, but recall, that users of the IECC may choose their own path to compliance based on the circumstances and the owner’s project requirements: either Compliance with IECC Chapter C4 (in its entirety), or Compliance with ASHRAE Standard 90.1-2010 (in its entirety).

The 2012 IECC now requires daylight harvesting requirements where the design professional seeks window-to-wall ratios greater than 30 percent (up to and including 40 percent) and/or skylight areas greater than 3 percent (up to and including 5 percent). Accordingly, the lamps for general lighting in the daylight zone areas shall be manually controlled by at least one multilevel photo-control (including continuous dimming devices).

Daylight harvesting is also required for certain spaces >10,000 ft2 (929 m2), with ceiling heights >15 feet (4.57 m), and located directly under a roof. No less than half of the floor area shall be located in a daylight zone for spaces meeting the aforementioned criteria and used as an office, lobby, atrium, concourse, corridor, storage, gymnasium/exercise center, convention center, automotive service, manufacturing, non-refrigerated warehouse, retail store, distribution/sorting area, transportation or workshop. Specific exceptions apply. (2012 IECC C402.3.2)

The ASHRAE 90.1 Standard, 2010 Edition, also requires daylight harvesting where the combined primary side-lighted area in any enclosed space equals or exceeds 250 ft2.  Accordingly, the lamps for general lighting in the primary side-lighted area shall be separately, but automatically, controlled by at least one multilevel photo-control or continuous dimming device.

Automatic daylighting controls for top-lighting are required by ASHRAE 90.1 where the total daylight area under skylights plus the total daylight area under rooftop monitors in an enclosed space exceeds 900 ft2.  Accordingly, the lamps for general lighting in the daylight area shall be separately, but automatically, controlled by at least one multilevel photo-control or continuous dimming device.

Daylight harvesting is also required by ASHRAE 90.1 for certain spaces >5,000 ft2 (465 m2), with ceiling heights >15 feet (4.57 m), and located directly under a roof.  No less than half of the floor area shall be located in a daylight zone for spaces meeting the aforementioned criteria and used as an office, lobby, atrium, concourse, corridor, storage, gymnasium/exercise center, convention center, automotive service, manufacturing, non-refrigerated warehouse, retail store, distribution/sorting area, transportation or workshop. Specific exceptions apply. (2012 IECC C402.3.2)

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Q: Does the code require at least one manual lighting control (e.g., a switch or pull-chain) for each area enclosed by floor-to-ceiling height partitions?

A: No, Users of the IECC may choose their own path to compliance based on the circumstances and the owner’s project requirements: either Compliance with IECC Chapter C4 (in its entirety), or Compliance with ASHRAE Standard 90.1-2010 (in its entirety).

Specific to lighting controls, the IECC requires each space to have at least one manual control and a control to reduce connected lighting power by 50 percent in a “reasonably uniform pattern.” The 90.1-2010 Standard requires each space to have at least one automatic control which shall be either manual on or automatic on with the first step at 50 percent power. In addition to all off and full on, Standard 90.1 buildings shall afford a control step between 30-70 percent power in all spaces, with limited exception.

Note additionally, that the IECC Section C405.2.2.2 and Standard 90.1 Section 9.4.1.2(a) go on to list specific locations where automatic lighting controls are required (in lieu of manual switching) that turn off the lighting within 30 minutes of all occupants leaving the space (i.e., vacancy control):

Occupancy sensors are now required in:

• Both IECC and 90.1: Classrooms/lecture halls, conference/meeting rooms, employee lunch and break rooms, restrooms, storage rooms, janitorial closets;
• 2012 IECC Only: in private offices and other spaces < 300 ft2
• Standard 90.1 Only: in private offices < 250 ft2, copy/print rooms, storage/supply rooms 50 ft2 > x < 1,000 ft2, and dressing/locker/fitting rooms

(2009 IECC 505.2.1, 90.1-2007 9.4.1.2)