Advanced Energy Design Guides: Free Download >
Justice in the Balance
At the Durham Consolidated Courthouse, designers took a measured approach to lighting—saving watts in some areas and splurging in others
ustice may be blind, but most people who enter a courtroom can see. In fact, it can be argued that a well-illuminated courtroom is vital for a fair trial. The right lighting scheme tells the courtroom audience where to look, helps jurors to distinguish witnesses’ visual cues, and gives the judge a clear view of the jury box, witness stand and the counsel tables—factors that can potentially affect the outcome of a case.
CONSERVE WATTS OUTSIDE
Watt-reduction techniques were employed throughout the facility, including in the design of the site and façade lighting. Security was a priority for site lighting, so 175-W metal halide pedestrian luminaires were selected for their good color rendering as well as energy efficiency. Compact fluorescent recessed downlights around the entrance canopy provide supplemental plaza lighting.
While the team took great care to contain illumination from pedestrian and area luminaires inside the site’s boundaries, they used light spill to their advantage where it couldn’t be avoided. Outside the site’s boundary, municipal HPS streetlights spill light onto the sidewalk and plaza for extra walkway illumination. Within the site, light from the brightly lighted interior lobby glows through the curtain wall glass exterior for an additional source of plaza illumination. Both sources increase site lighting levels and enhance security without increasing the lighting load.
Another source that serves two functions is the fluorescent lighting in the six-story stairwell tower. Integrated near the curtain wall within the interior of the stairwell, 32-W linear T8 fluorescents in 3,500K provide functional illumination and make the tower appear to glow from within. Inside the tower, the horizontal structural banding helps shield the lamps from view, while outside “there is a differential pattern in light that creates a piano key effect,” says Burt. “It’s a signature feature of the building.”
LOWER LOBBY LOADS
Like the tower, the 2.5-story lobby is a signature feature—one mandated by the government sponsor to give court facilities a sense of formality. WZMH interpreted the requirement as a glass box with connective public arteries that feed into a main atrium. “The architect didn’t want the ceiling to be the focal point in the lobby, but they wanted to create visual interest,” says Burt.
Stantec’s solution was to arrange multiple 4,000K, 93 CRI, PAR38 metal halide luminaires in rows across the 30-ft-tall ceiling. Suspended from ceiling slots that span the horizontal plane, the luminaires create a rhythmical pattern and emphasize the lobby’s linear architectural elements. What’s more, with four individually aimable lamps, the luminaires “gave us the opportunity to direct light onto the information area and the metal detectors below,” says Burt.
The glass curtain wall adds an abundance of natural light to the lobby space and connecting corridors, significantly reducing the amount of electric light needed to illuminate the space during the day. Recessed downlights and wall washers with CFLs were used to supplement the daylight in the public corridors. To minimize light loads even further in these areas, the team reduced general light levels from 19 footcandles to 14 fc and concentrated light over seating areas.
SPEND WATTS WISELY
Anyone who has ever saved for a big purchase knows the thrill of finally being able to cash in on their hard work. But for Stantec, “splurging” was hardly a free-for-all. In fact, even the areas where the team could expend extra watts—the detention facility and the courtrooms—were meticulously designed so that no watt was wasted.
While security needs dictated lots of light, a change in the detention cell design complicated light levels at Durham Courthouse. “As we were designing the project, the government changed the cell design from bars to glass and added cameras that have to shine through the glass. We had the challenge of working to elevate light levels within cells and lower them outside the cells so that the cameras would work properly,” explains Burt. Recesssed, maximum security luminaires with T8 lamping provide illumination of 50 fc in cells and 25 fc outside. Cameras were positioned to view perpendicular to glazing to reduce glare in combination with the light level differential.
Balancing light levels was also key in the courtrooms. “They are rather difficult to light. They should be quiet and dignified,” but they should also have a sense of hierarchy in keeping with the “theater” of the courtroom, says Burt, who compares courtroom lighting to stage lighting. “Your attention should be drawn to the person on stage—in this case, the judge—so the brightest area should be the dais, followed by the well where the clerk and counsel sit, and then light levels can fall off when you get to the audience.”
Target light levels at Durham were initially set at approximately 46 fc, but Burt recommended that they be staggered to accommodate the hierarchical staging: 56 fc at the dias, 46 fc at the well and 33 fc in the audience. To draw attention to the lead actor—the judge—three fluorescent light sources were focused on the dias: white cove lights the top of the wood panel behind the dias, downlights recessed in the drop ceiling above illuminate the remainder of the panel and linear recessed T5HO luminaires that line the center of the room provide ambient light. White cone and lenses were added to the downlights to shield lamps from judges’ views.
For the supporting cast—the clerk, counsel, the jury and the witness—“it was important to illuminate the side walls as evenly as possible,” says Burt. “In other courtrooms, we’ve seen downlights that scallop terribly or coves that don’t distribute down. So, we made sure to use a very high-performing cove on the side and back walls. It distributes light into the middle of the room and gives the jury a clear view of the witness stand.” Lighting controls (Lutron) can dim the lights to accommodate AV equipment that may be used during trials.
As in the detention areas, the lighting had to be tweaked to accommodate unanticipated design changes. “We created full-size mock-ups to accommodate a specific room layout, but in the end there were 20 different dimensions for the 33 total courtrooms,” says Burt. “We spent around 100 hours assisting the contractor in tuning the lights to achieve the right light levels.” Call it their civic duty.
Photos: Shai Gil Photograpghy