Know-How: Skylights

Many school designers extol the benefits of natural light in learning environments. Studies indicate that many students perform better in classrooms that have greater amounts of natural lighting. Using daylight to illuminate facilities also can reduce energy use.

But before school administrators rush out and install skylights, they should realize that indiscriminately adding skylights to buildings won't give schools the desired benefits.

“The design of a skylight is critical,” says Michael Nicklas, a principal architect at Innovative Design in Raleigh, N.C. “You want to be able to control the light to enhance productivity.”

A study often cited by daylighting proponents is one conducted by Heschong Mahone Group in Fair Oaks, Calif. In the Capistrano school district in Orange County, Calif., researchers found that students in some skylighted classrooms performed 19 and 20 percent better in reading and math than students in rooms without skylights.

But one distinction not always made clear by those citing the Heschong study is that the student-performance boosts occurred in classrooms with well-designed skylights. The study described a well-designed skylight as “one that diffused daylight throughout the room and which allowed teachers to control the amount of daylight entering the room.”

In fact, the study notes that in Capistrano district classrooms with a different type of skylight, student performance in reading was 21 percent lower than students in classrooms without skylights. The types of skylight that produced this negative effect were ones without any controls. They allowed direct sunlight into a room and caused distracting glare.

Schools should avoid horizontal skylights in favor of roof monitors, Nicklas says. A roof monitor is a raised section of roof that includes a vertical glazing. The most effective roof monitors have south-facing glazing, which lets heat and light in during the winter and keeps it out in the summer.

The benefits of roof monitors can be enhanced with baffles, diffusers and louvers to control and distribute the light.

Another effective strategy is to add a light shelf. It is a horizontal surface, installed a few feet below the top of a window, that deflects the direct sunlight toward the ceiling and provides diffused light throughout the room.

NOTABLE

+19 PERCENT

Difference in reading scores for Capistrano School District students in classrooms with well-designed skylights, compared with district average.

+20 PERCENT

Difference in math scores for Capistrano School District students in classrooms with well-designed skylights, compared with district average.

-21 PERCENT

Difference in reading scores for Capistrano School District students in classrooms with poorly designed skylights, compared with district average.

+8 PERCENT

Difference in reading scores for Capistrano School District students in classrooms with windows that could be opened, compared with district average.

+7 PERCENT

Difference in math scores for Capistrano School District students in classrooms with windows that could be opened, compared with district average.

Source: Daylighting in Schools, An Investigation into the Relationship Between Daylighting and Human Performance, Heschong Mahone Group.