In the 21st century, educators and school facility designers have come to embrace daylighting strategies as a way to deliver instructional spaces that not only use energy more efficiently but also help students perform better academically.

So if daylight is good, more daylight is better, right? Well, if an unplanned nap ever turned your short sunbathing session into a lobster-red blisterfest, you know that more sun isn’t necessarily better.

Too much light, especially direct rays that create glare, can be distracting to students and bring unwanted solar heat to a learning space.

“Location of windows in a building must be designed in such a way as to avoid the admittance of direct sun on task surfaces or into occupants’ eyes,” says the National Institute of Building Science’s Whole Building Design Guide.

“The aim of an efficient daylighting design is not only to provide illuminance levels that are sufficient for good performance, but also to maintain a comfortable and pleasing atmosphere,” the guide states. “Glare, or excessive brightness contrast within the field of view, is an aspect of lighting that can cause discomfort to occupants.”

The seminal study that accelerated the impetus for maximizing natural light in schools, a 1999 report from the Heschong Mahone Group, found that students in classrooms with greater amounts of daylight scored better in math and reading tests.

But in that study and a 2003 follow-up, researchers also found that sources of glare in a classroom negatively affected student performance.

“This is especially true for math learning, where instruction is often visually demonstrated on the front teaching wall,” the 2003 study said. “…Direct sun penetration into classrooms, especially through unshaded east- or south-facing windows, is associated with negative student performance, likely causing both glare and thermal discomfort.”