Lighting the Way

Designers are working to refine daylighting strategies to provide energy-efficient classroom environments conducive to learning.

In recent years, more education administrators and designers have embraced the potential benefits of daylighting. They have been persuaded that using natural light to illuminate facilities enables schools and universities to conserve energy and provide a learning environment in which students perform better.

For daylighting advocates, the challenge of persuading reluctant administrators to incorporate daylighting into their facilities has eased. Now proponents are trying to figure out new techniques and strategies that will tap the full potential of daylight in schools.

Among the daylighting tools available to designers: building orientation, window placement, skylights, roof monitors, clerestory windows, overhangs, light shelves, baffles, shades and reflective surfaces. Proponents of daylight are working continually to find the proper mix of those elements to provide energy-efficient, naturally illuminated learning environments.

“To get half of the energy savings possible from daylighting is one of the easiest things to do,” says Michael Nicklas, president of Innovative Design in Raleigh, N.C. “To get the full energy-savings potential from daylighting is one of the hardest.”

Dark ages

The 1960s began a dark period for school design in a lot of communities. Many school systems decided that the new classrooms they were constructing didn't need as many windows as their older facilities.

The classrooms would get less natural light, but teachers could easily flip on a switch and solve that problem. Planners were more focused on the perceived benefits of fewer windows. Fewer openings in the building envelope meant a facility could be heated or cooled more efficiently, especially as air conditioning became more prevalent. Fewer windows meant less noise would infiltrate a classroom and distract students. Fewer sightlines to the outside meant that students would be less prone to daydream about what was happening beyond the school walls. Fewer windows meant fewer temptations for would-be vandals and intruders, and fewer repair jobs for the maintenance staff.

But as those buildings aged, some flaws began to surface. In some facilities, having fewer windows resulted in poor ventilation and problems with indoor air quality and “sick building syndrome.” The reliance on electric light, usually from fluorescent fixtures, was not as aesthetically pleasing as natural light. Advocates of daylight could argue that these window-deprived classrooms were not ideal learning spaces, but they didn't have data to back up their assertions.

The tipping point that triggered wider embrace of daylighting in schools was a 1999 study by the Heschong Mahone Group in Fair Oaks, Calif. It studied classroom daylighting in three school districts: Seattle Public Schools; the Poudre School District in Fort Collins, Colo.; and the Capistrano School District in Orange County, Calif.

The research concluded that in classrooms with well-designed daylighting strategies, students performed significantly better in math and reading. Instead of relying on instinct or anecdotal evidence that daylighting created a better learning environment, proponents had scientific data to make their arguments for them.

Acceptance of the Heschong study, together with a general trend toward greater environmental responsibility and sustainably designed facilities, has led many architects and administrators to make daylighting an integral component of new school designs.

Throwing a curve

The daylighting strategies in use at Northern Guilford Middle School in Greensboro, N.C., are an example of the efforts to deliver more natural light more efficiently to learning spaces. Nicklas says that Innovative Design's plan for the 140,000-square-foot school, which opened in January, uses a new technique that reduces by 40 percent the glass area that provides natural lighting, compared with other daylighting strategies.

The goal of the design is to have natural light be the primary source of illumination for all educational and administrative spaces during two-thirds of daylight hours.

The classrooms in the middle school have curved, white lightshelves made of translucent acrylic that are situated below south-facing clerestory windows. The translucent panels and the reduced amount of glass reduce the glare in classrooms and enable daylight to be spread more uniformly throughout the space. Daylight enters through the clerestory windows and is bounced off the translucent lightshelves onto highly reflective ceiling tiles. Some light also filters through the acrylic lightshelves.

The classrooms also include a soffit situated to provide shade for the classroom areas that will have projection screen and television monitors. Integrating the shading technique into the design eliminated the need for shading devices, which often are left closed and counteract daylighting strategies.

Other daylighting techniques at Northern Guilford: The facility is oriented on an east-west axis to maximize the southern solar potential for daylighting. East and west glazing is minimized to reduce heat gain. In the gymnasium and dining areas, roof monitors admit daylight into the space, and translucent fabric baffles eliminate glare and diffuse the light throughout the space.

To supplement the daylight, Northern Guilford has an indirect fluorescent lighting system that is controlled by occupancy sensors and photo-cell sensors. The artificial lights can be dimmed and brightened in response to daylight conditions.

Nicklas believes the Northern Guilford design shows progress in daylighting techniques, but concedes, “It's not as good as it could be.” He hopes that as designers learn more about daylighting and which strategies are most effective, they will be able to build facilities that deliver the desired doses of daylight with maximum efficiency.

“We've tried everything out there,” says Nicklas. “It's difficult to project this very precisely. We try to tweak the programs we have. More is technically possible, if the tools we had were more refined.”

Kennedy, staff writer, can be reached at [email protected].

Sidebar: Bright ideas

The Lighting Research Center at the Rensselaer Polytechnic Institute in Troy, N.Y., has established a “Daylighting Dividends” program to promote natural light as a way of improving indoor environmental quality.

Its “Guide for Daylighting Schools,” developed by Innovative Design, gives designers and administrators numerous tips for incorporating the use of natural light into a building's plans.

A successful school daylighting strategy must:

  • Consider human factors

    “The most important aspect of good daylighting design is to understand how it affects human nature,” the guide says. If daylighting efforts do not result in a superior environment, “the habit of walking into a space and turning on the lights will never be broken,” the guide states.

  • Consider energy ramifications

    “From an energy perspective, the worst thing that you can do is to implement a daylighting strategy that is not quite good enough,” the guide says. Insufficient daylight leads to greater reliance on electric lights, which together with the daylight can overheat a space.

  • Account for site constraints and benefits

    “The potential for cost-effective daylighting is greatly enhanced by elongating the school on an east-west axis and locating high-priority spaces on the north and south exposures,” the guide recommends.

  • Select well-integrated daylighting strategies

    Some designers looking at daylighting for the first time may be concerned that the project will exceed its budget and may never truly integrate daylighting components. “To do (daylighting) well, the many different aspects of the school's architecture, landscape and engineering must be considered,” the guide says.

  • Optimize the most appropriate strategies

    Among the strategies: south-facing roof monitors; lightshelves on south walls; high transom glazing on north walls; highly reflective ceiling tile; directional blinds; dimming controls.

  • Accurately simulate daylighting performance

    “The designer should conduct detailed daylighting computer simulations that compare options,” the guide states, including variables such as different locations on a site and different design components.

  • Verify and modify the design process

    “It is essential that you visit the (completed) school and … compare the performance with your computer and physical models,” the guide says. “Part of your post-occupancy analysis should also be an evaluation of how well the human factors were addressed.”

NOTABLE

40

Percentage reduction in glass area at Northern Guilford Middle School compared with typical daylighting strategies.

20

Percentage reduction of the peak cooling load at Northern Guilford Middle School attributable to daylighting strategies.

$160,000

Cost savings in air-conditioning system at Northern Guilford Middle School attributable to daylighting and other sustainable strategies.

Source: Innovative Design

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