By Craig DiLouie
In his new book Learning to See: A Matter of Light, legendary lighting designer Howard Brandston writes about what he calls the Political Energy Law: "Lighting consumes energy; therefore, when energy is abundant, use may increase, and when energy is scarce, it must be rationed." He notes that human visual requirements are not part of this law.
The bottom-line concern is not about making design vanilla but instead crossing a critical threshold and promoting bad lighting in the name of energy economy. States such as California are facing a choice of either significantly increasing supply or reducing demand over the next 10 years.
Efficiency must come from somewhere, either by squeezing more watts out of lighting technology or reducing light levels. At some point, we will squeeze out all of the watts and lumens that are available.
Researchers have begun testing the utility of innovative lighting systems to see how far we can go with efficiency without jeopardizing fundamental lighting quality - by integrating highly efficient design and technology, lighting best practices, and controls. Here are two such systems:
Integrated Office Lighting System (IOLS). This lighting system consists of low-level general lighting for ambient illumination combined with a flexible array of freestanding and undercabinet LED workstation task lighting controlled by an occupancy sensor. The task/ambient design has been demonstrated by the California Lighting Technology Center (CLTC) to achieve a 0.5-0.7 watts/square foot lighting power density, 36 to 55 percent lower than ASHRAE 90.1-2004/2007. The use of the sensor controlling the task lighting was found to reduce energy consumption by another 20 to 30 percent.
Glare and shadows are common complaints among office workers; the direct/indirect fixtures provide soft, uniform light while the LED task lighting (Personal Lighting System, or PLS, developed by manufacturer Finelite and CLTC) eliminates shadows, minimizes glare, and enables users to adjust their task lighting to their individual needs. While the human factors aspect of IOLS should be tested further, researchers reported anecdotally that users expressed higher satisfaction with their lighting.
The catch: Task/ambient lighting systems require a higher level of coordination in an integrated design approach. For more information, visit cltc.ucdavis.edu/content/view/83/85.
Integrated Classroom Lighting System (ICLS). This classroom lighting design template consists of rows of direct/indirect fixtures mounted parallel to the window and spaced 14 to 15 feet apart with another fixture mounted over the teacher's whiteboard at the front of the room. (A third row can be added for a larger classroom.) Each direct/indirect fixture contains three T8 lamps (one inboard, two outboard), providing downlight electrically separated from two outboard lamps that give both uplight and downlight.
Besides using a master switch at the door, the teacher can control the lamps using several switches mounted near the whiteboard, allowing a change of light distribution from General (downlight OFF, uplight/downlight ON) to AV (and reading) mode (downlight ON, uplight/downlight OFF). Dimming is offered as an option.
Because all three lamps can't be operating at the same time, the maximum power density is capped at about 0.8 watts/square foot. An occupancy sensor and optional photosensor maximize energy savings. ICLS, created by Finelite, was tested by the Lighting Research Center (LRC) in 28 classrooms and seven schools and found to produce an average 0.73 watts/square foot—nearly 50 percent lower than ASHRAE 90.1-2004/2007.
What's more, the system provides flexibility to adapt to the use of the AV equipment that is becoming increasingly common in today's high-tech classrooms and realizes best practices. Although again more research may be needed to confirm user satisfaction, the LRC found that the teachers generally preferred ICLS to their previous lighting systems.
For more information, visit Finelite.com/products/icls-overview.html.
Craig DiLouie (firstname.lastname@example.org), a lighting industry journalist, analyst, and marketing consultant, is principal of ZING Communications.