With the help of 21st-century technology, architects are harnessing that oldest of Earth's resources - sunlight - as never before.

Builders have been manipulating it for centuries, says Dr. Wayne Place, architecture professor and head of the daylighting lab at N.C. State's College of Design. Consider the Gothic cathedrals, he says. "Basically, they were all about two things, structure and light."

The difference today is that, with computers and other design tools, architects and daylighting consultants can make maximum use of the sun's benefits while blotting out its heat and glare.

"When the sun gets down low on the horizon, it's like a headlight shining through your window," says architect Steven Sweat of Neighboring Concepts in Charlotte. And that, says Dr. Dale Brentrup, professor and head of the daylighting lab at UNC Charlotte's College of Architecture, can send air conditioning bills through the roof.

During the gas crises of the 1970s, energy bills and uneasiness about dependence on foreign energy sources jump-started the current embrace of the Earth's oldest resource.

Soon, other reasons for including as much daylight as possible in new buildings emerged. It's a nonpolluting energy source, and the U.S. Green Building Council started giving LEED points for it.

Studies in selected elementary schools in Washington State, Colorado and California and in a large retail chain showed that both children's grades and retail sales went up in the presence of ample daylight.

N.C.'s best examples

Showcase buildings in North Carolina have bought into the philosophy, using everything from exterior glass walls individually tailored to the amount of sunlight (University of North Carolina at Charlotte's new $50.4 million Center City building in Charlotte) to 11-foot-2 ceilings with super-tall windows (the Wildlife Resources Commission's 2005 LEED Gold-rated headquarters on Raleigh's Centennial Campus).

Gantt Huberman Architects of Charlotte, partnering with Kieran Timberlake Architects of Philadelphia, divided the 12-story UNCC building into multistory blocks cantilevered above each other. They give both shade and a distinctive appearance that the university likens to "a stack of books."

Daylighting has even enabled Mecklenburg County to squeeze energy savings out of the conversion of the 1960s Freedom Mall on Freedom Drive into the Valerie A. Woodard office building.

With the help of the UNCC lab, architect Little & Associates devised windows shaded by brightly colored plastic fins and horizontal shelves, plus a phalanx of skylights that beam light into the interior of the 400,000-square-foot building.

To tame the sun's glare

Unlike flowers, which turn toward the sun, so-called daylighted buildings turn away from it. That ball circling overhead is most glaring in east- and west-facing windows, somewhat glaring in those facing south, but perfect coming from the north.

To deal with the glare that remains, architects and the daylighting labs employ a variety of measures, from shades - both stationary and hand-manipulated - to tinted glass.

Young children can too easily get tangled in venetian blinds, says Brentrup. When the UNCC lab and Applegate Architects of New Bern designed First Environments Early Learning Center for young children in Research Triangle Park, they placed a trellis outside the windows, so that climbing greenery could serve as both shade and teaching tool.

Concern for Earth's natural resources was also a factor in Raleigh architectural firm Williard Ferm's design for the wildlife commission headquarters, says Mark Williard.

More than half the 2.2-acre site was left natural, and the narrow building's windows have a view of grass, a wetland, rabbits, birds and butterflies.

To reduce glare and beam light into the interior - where it's passed on through glass office partitions - an interior light shelf or horizontal reflective bar bisects the windows, bouncing light up to the ceiling, where it's reflected down again.

Models vs. simulations

The balancing act of light versus heat and glare starts with that old-fashioned tool, the scale model, but moves into the 21st century with dozens of computers that can "batch process" simulated lighting conditions for an entire building.

"Twenty years ago we just had the scale model," says Brentrup. Now, with UNCC's 52 connected computers determining where and with what intensity light hits, "we can get a (computer) model out in an hour," he says.

First, a heliodon - a telescope-shaped instrument that can mimic the sun at any hour in any latitude - is focused on the scale model to see where its rays fall through windows and doors.

NCSU makes its models big enough to stick your head in, says Place. "A computer immersion envelope will never tell you when a surface is so bright you can't look at it."

Architects fashion shades and light shelves from cardboard, then submit the doctored model to a room where the sky is artificially cloudy. They may learn that their fixes are like sunglasses indoors: too much of a good thing.

Steve Sweat of Neighboring Concepts architect says, "There was a lot of going back and forth" to change the angle of light-colored ceiling panels for Revolution Park Sports and Learning Academy in Charlotte. He wanted the maximum amount of northern light coming through a large window and a clerestory - high windows above eye level - to bounce off the panels, then off light-colored floors and walls.

Information gathered through light sensors on the model is then fed into the computers for refining.

Save energy, build morale

The end result is buildings that both save energy and employee morale, daylighting advocates say. The daylighting is often paired with other energy-saving measures, like photometric controls that dim or cut off artificial lights at times of ample sun.

The wildlife commission has carefully monitored energy use the last two fiscal years, and discovered that its building used 19 to 24 percent less than the building-industry minimum standard.

In a building of that size - 75,000 square feet - "it adds up," says Michael Shelton, facilities mechanical engineer. "There is the potential to save quite a bit of money."

And at Gantt-Huberman-designed Charlotte-Mecklenburg Utilities' Environmental Services facility, laboratory analyst Gina Kimbell marvels that "we actually never have to turn the lights on in this office."

At the lab, which analyzes all Charlotte's drinking water, storm water, and wastewater, employees need "to see everything, really well," says Lead Water Quality Technician Chris Sekerak.

The ample daylight, he says, not only makes that possible, "it's easy on the eyes. Keeps you alert and awake."