Enrollment in public elementary and secondary schools rose 24 percent between 1985 and 2006, according to the National Center for Education Statistics. In 2006, nearly 50 million students were using more than 385,000 school buildings.
According to the U.S. Department of Energy, in 2003, 234,000 school buildings—representing nearly 6.3 billion square feet or 63.4 percent of floorspace—were built before 1980. Forty percent of floorspace had never been renovated.
From this, I conclude that the number of students keeps going up while the educational building stock keeps getting older. As a result, we are currently in the midst of a major surge in construction spending—more than $80 billion in 2007, making education the largest nonresidential construction market.
Attending this surge is the high-performance schools movement. High-performance schools are designed to improve the learning environment with good lighting, indoor air quality, temperature, humidity and acoustics while minimizing energy, resources and cost.
Reducing lighting operating costs—typically 30 to 40 percent of school utility expenses—is welcome in most schools. Most states require a minimum level of efficiency for new schools with energy codes at least as stringent as ASHRAE 90.1-1999/2001, which prescribes a maximum lighting power density (LPD) of 1.6W per square foot for classrooms, and ASHRAE 90.1-2004/2007, which prescribes a maximum LPD of 1.4W per square foot. California’s Title 24-2005 targets 1.2W per square foot. The overall LPD trend is downward.
That this is happening without public outcry tells us that either classroom lighting is getting less visually demanding or technology is getting more efficient. In fact, classroom lighting is becoming more demanding. Many new classrooms have whiteboards, computers, Internet connectivity and multimedia equipment, requiring extensive flexibility from the lighting system.
Can lighting design and controls increase energy savings while serving flexible audiovisual classrooms?
To provide one answer, the New York State Energy Research and Development Authority sponsored a demonstration project, featuring a new Integrated Classroom Lighting System (ICLS) created by Finelite Inc. It was installed in 28 existing classrooms at seven schools and universities. The Lighting Research Center (LRC) assessed teacher and student satisfaction as well as installer acceptance.
The result was a flexible design approach that satisfies A/V needs and improved teacher and student satisfaction while reducing LPD to an average 0.73W per square foot, nearly 50 percent less than ASHRAE 90.1-2004.
The ICLS template typically consists of two rows of pendant-mounted direct/indirect fixtures, with a wallwashing whiteboard fixture mounted at the main teaching board. The fixtures are mounted parallel to the window and spaced 14 to 15 feet apart. Each fixture features three 3,100-lumen, high-performance T8 lamps, one inboard lamp providing downlight electrically separated from two outboard lamps providing both uplight and downlight.
Aside from using a master switch at the door, the teacher can control these lamps using a “teacher control center” located within 6 inches of the main teaching board, which allows him or her to change the light distribution from general mode—downlight off, uplight/downlight on—to A/V (and reading) mode—downlight on, uplight/downlight off. Another option, A/V dimming mode, allowed the teacher to activate and then dim the downlight component due to a dimmable ballast. Because all three lamps cannot be on at the same time, the maximum LPD is capped at about 0.8W per square foot. A separate, specially labeled switch activates the whiteboard fixture.
To increase energy savings even further, a dual-technology occupancy sensor is mounted on the ceiling plane between the two rows of pendants, ensuring the lights are automatically shut off if the room is unoccupied. Optionally, a photosensor could be added, adjusting light output based on daylight availability. All controls are connected with a Cat 5 plenum-rated, low-voltage line with plug-and-play connections.
LRC found that teachers generally preferred ICLS to the previous lighting system. Students also rated it favorably.
The ICLS template uses standard pre-engineered lighting technology, which can be customized for different application needs, such as varying ceiling heights, and was installed for $1.83—$2.29 per square foot. (However, options—such as daylight switching and a third fixture row to increase uniformity—add to the cost.) According to LRC, the installers generally characterized the system as “easy to install.”
Direct/indirect lighting and separately controlled fixtures for general and main teaching board lighting are considered best practices by the Collaborative for High Performance Schools (CHPS). Optimizing this approach as a system with integrated controls maximizes its utility for A/V functions while minimizing energy consumption.
Many of the research findings are being incorporated into best practice developed by the CHPS as well as the U.S. Green Building Council’s LEED for Schools rating system, according to LRC.
DILOUIE, a lighting industry journalist, analyst and marketing consultant, is principal of ZING Communications. He can be reached at www.zinginc.com.