general mode, the lighting places 20 to 40 footcandles on desktops. In AV mode, the placement is 5 foot- candles, while limiting vertical light levels to 3 footcandles on the white- board or projection screen and 7 to 15 footcandles on the surrounding teaching wall. CHPS encourages flexible controls by offering up to four points. For two points, the designer must provide indirect/direct lighting for all general- purpose classrooms. Control enables a choice of general or AV ( 10 to 30 footcandles in the student zone; max- imum 7 footcandles on the screen) modes. Separate control must be provided for whiteboard vertical lighting. Where daylight-responsive controls are present, the light sensor takes precedence over manual dim- ming for the upper light-level limit. For two additional CHPS points, the designer can specify enhanced teacher controls, which provide teacher control at the front of the classroom for general/AV mode, whiteboard control, and a manual override of the occupancy sensor time delay during written exams. The occupancy sensor signal in turn must be linked to a school-wide manage- ment system. Tunable-white lighting allows de- ployment of another emerging dimen- sion of control, which is correlated color temperature (CCT) tuning by activity or time of day. CCT tuning may be combined with intensity con- trol to enable additional lighting modes throughout the day, such as “focus” for test taking, and “calm” to help calm an excited class.
Automatic Controls ASHRAE/IES 90.1-2010 and -2013 require manual control, occupancy sensing, and daylight-responsive con- trols. Many commercial building en- ergy codes are based on these stan- dards or the International Energy Conservation Code. At a minimum, the occupancy sen-
sor must automatically turn the lights off within 30 minutes of the space being vacated. If the sensor automati- cally turns the lights on, it must acti- vate the lights to 50% or less of light- ing power (bilevel switching). For manual control, one or more manual switches must be installed at the entrance to control all lighting in the room. Additional manual controls may be installed as needed to support visual needs through flexibility. Daylight-responsive controls must be installed where daylight is present through either sidelighting or top- lighting. The output may be bilevel switching, step dimming, or continu- ous dimming. Lighting practice for educational facilities is changing alongside the teaching environment and its needs. Manufacturers have experience and offerings optimized for this market and are therefore an excel- lent resource. To learn more about recommended practice, consult RP- 3 published by the IES. To learn more about the CHPS, download the applicable CHPS criteria at CHPS.net. To learn more about energy code requirements, con- sult the energy code in effect in the project’s jurisdiction. ; DiLouie, LC, principal of Zing Comm- unications ( zinginc.com), is a journalist, analyst, marketing consultant, and author. Reach him at email@example.com.
www.tEDmag.com May 17 • the ELECTRICAL DIS TRIBUTOR 67
Some lighting control systems offer a choice of CCT. For example, the system pictured offers
four settings: “calm” mode (top), with a standard intensity and warm shade of white light; “fo-
cus” mode (bottom), with the highest intensity and a cool shade; “normal” mode, with standard
intensity and neutral shade; and “energy” mode, with highest intensity and very cool shade.