Green Lights

In April, the U.S. Green Building Council released an environmental rating system for K-12 schools. Called“LEED (Leadership in Energy and Environmental Design) for Schools for New Construction and Major Renovations,” it is one of nearly a dozen programs developed by the USGBC to guide green design and construction on specific types of buildings.

As a rating system, LEED recommends sustainable building systems. Projects that aim for LEED certification must register with USGBC. Design elements that satisfy the LEED recommendations earn points. LEED issues four certifications based on total points. From lowest to highest, they are: certified, silver, gold, and platinum.

As a design tool,“LEED is creating a more holistic (design) process,” says Tim Hill, electrical discipline director in the Indianapolis offices of Fanning Howey Associates, Inc.

In short, green design and construction focuses on how each building system affects other building systems and how the overall building affects the performance of occupants.

That said, LEED for Schools also promotes the use of dramatic natural daylighting in ways that are altering the design of K-12 school classrooms, lobbies, media centers, cafeterias, auditoriums, and gymnasiums. In short, natural light is energizing the look and feel of schools.

Key to LEED’s lighting recommendations is study after study that has proven natural daylight effective in raising student performance, increasing teacher retention, and boosting administrative productivity.

LEED for Schools also recommends designing an artificial lighting system that works with the daylighting system.

But LEED for Schools does not shortchange holistic design. It also recommends ways in which the lighting systems can complement and work with other building systems.

Lighting The Way For Students

According to “Greening America’s Schools: Costs and Benefits,” a 2006 report co-sponsored by the USGBC, 17 studies conducted from the mid-1930s through 1997 found that good lighting in schools “improves test scores, reduces off-task behavior, and plays a significant role in the achievement of students.”

The report also notes that another 53 studies contend that increased “daylighting” fosters higher student achievement.

“Greening America’s Schools” makes the point that natural light does more than improve student performance, it raises the performance of everyone in the school. One study of office worker productivity by a utility company discovered that workers with windows and attractive views performed 10 percent to 25 percent better on tests. In addition, offices designed without glare enabled workers to outshine workers dealing with glare by 15 percent.

LEED for Schools recognizes these findings and recommends that 75 percent to 90 percent of classrooms employ daylighting. The program also recommends that 75 percent of all other spaces in the school make natural light a primary source of light.

Another green or sustainable design key provides building system controls for building occupants whenever possible. In the area of lighting, LEED for Schools recommends individual lighting controls for 90 percent of personnel in administrative offices.

Classrooms, of course, provide teachers but not students with some control over lighting. LEED recommends that classroom lighting switch back and forth between two modes — general illumination and audio/visual.

Fanning Howey’s Tim Hill notes that while individual lighting controls are important, LEED for Schools does not mention the use of daylighting controls. “I think that there should be a credit for daylighting controls,” Hill says. “We’ve talked about this in several of our school designs, and we’ve decided to pursue points for these kinds of controls under LEED’s innovation and design section.”

According to Stephen Beede, market development managers with Lutron Electronics Co. Inc., a lighting controls manufacturer in Coopersburg, PA, devices such as occupancy sensors, daylight sensors, and automatic and manual dimmers adjust artificial lighting to suit available levels of natural light.

“We have taken measurements room by room to study how effective these systems can be,” Beede says. “In one case study, an elementary school in Palm Beach County, FL, reduced its consumption of electricity for lighting by an average of 50 percent. On some days, the savings was 60 percent. Another school in Allentown, PA, averaged a savings of 53 percent.”

Beede also points to the Sidwell Friends School in Washington, D.C., the first school in the world to earn a LEED platinum certification. “Sidwell Friends has incorporated a variety of lighting strategies, including light shelves, clerestory windows, skylights, daylight dimming controls occupancy sensors, and manual controls,” he says. “The facility manager anticipates reducing the School’s overall lighting load by 90 percent.”

Lighting That Works With Other Building Systems

LEED for Schools also encourages designers to consider how one building system affects other building systems.

“In the past, lighting designers might have been shooting for 60 foot-candles, but thought it was even better if they got to 75 foot-candles — there were no consequences,” Hill says. “Today, of course, we’re lighting to the correct level.

“In the past, mechanical engineers matched the HVAC systems to the lighting load to get to a comfort level in the building. Then the engineer may have factored in an extra half watt per square foot just to be safe. That doesn’t happen anymore either.

“LEED is forcing us to think about how our system affects other systems.”

The main holistic angle is that natural light reduces the need for artificial light. Less artificial light not only reduces lighting costs, it also cuts the heat gain inside a building caused by lighting. In turn, the building’s heating, ventilating, and air-conditioning system consumes less power.

But lighting issues also affect other design considerations. For instance, the use of natural light affects the orientation of the entire building on the site. Designers will position classroom windows to take advantage of natural light. They will design landscaping and exterior shading accents to prevent bright sunlight from heating the structure in the summer. They will look at ways to allow sunlight to help warm the building in the winter.

While it would be inaccurate to call the treatment of lighting in LEED for Schools the most important part of the rating system, LEED for Schools most certainly give a green light to designs with a flair for the dramatic look of sweeping glass facades and the management of natural light.