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Innovative, lens-shaped ceiling highlights landmark new federal courthouse in Phoenix

DuPont ™ SentryGlas ® ionoplast and Butacite ® PVB interlayers have been used to stunning effect in an innovative, lens-shaped ceiling over a special proceedings courtroom that is the showcase of a landmark new federal courthouse in Phoenix, Arizona by architect Richard Meier (completion: September 2000).

The ceiling, designed by Luke Lowings and James Carpenter of James Carpenter Design Associates, won the 1998 General Services Administration (GSA) Design Award (Art and Architecture Program) for its synthesis of architectural and aesthetic goals.

Chief Judge of the Arizona District Court, Robert C. Broomfield, also chaired the committee of judges that wrote the GSA guidelines. He told LGN: "The courtroom, and the entire building which is bathed in glass and light, symbolizes a new millennium courthouse in a new millennium city."

"A GIANT NATURAL LIGHT FIXTURE"

Richard Meier told LGN in a recent interview: "The lens ceiling to the drum adds a really special dimension to the central courtroom. It elegantly meets GSA guidelines regarding ceiling height yet by its very form makes the space feel much more open, and makes the ceiling much higher." Associate partner with Richard Meier and Partners, Don Cox, explained: "The laminated glass ceiling is in effect a giant natural light fixture. It diffuses light coming in from all angles during the day and bathes the courtroom in a soft light while opening it up to the sky. We anticipate that the unique atmosphere given by Carpenter's lens ceiling will make the special proceedings court the showcase space within the whole courthouse."

Another important function of the glass ceiling and walls is to keep noise out of the courtroom. The dish-shaped ceiling is optimal for acoustics and distributes sound excellently within the courtroom whereas traditional dome-shaped atria tend to carry sound away.

JCDA's Jamie Carpenter and Luke Lowings told LGN: "We wanted to create the lightest possible structural solution. Initially, Richard (Meier) wanted no ceiling at all – he wanted the whole drum to be open so that people felt connected to the Arizona sky. The lowest layer of the lens is hanging purely by its adhesion to SentryGlas® whereas we used Butacite ® for the rest of the ceiling. Both interlayers fulfill safety requirements for overhead glazing."

"SENTRYGLAS® ESSENTIAL"

David Passarelli of laminator Dlubak Corporation explained: "The properties of SentryGlas® were essential for the fabrication of the lens roof. The interlayer continues out beyond the trapezoidal glass panes and sticks out at each end to form a tab. We drilled through those tabs and used them as structural members to help support the roof and act as buffers in the case of seismic loading. DuPont's ionoplast is the only interlayer I know of which could perform this specific function. Its combination of rigidity and strength meant that we could actually drill holes through it."

Matt King from structural engineering firm Ove Arup commented: "The lens ceiling has to resist seismic loads, which can be problematic in a brittle glass structure. We wanted to introduce some 'softness' into the system and a corner tab fixing detail allowed us to do just that. Instead of rigidly joining the pieces of glass together, the tabs will 'give' in the event of an earthquake – they quite literally act as shock absorbers!"

"A CENTRAL ARTISTIC SYMBOL FOR THE CITY OF PHOENIX"

The court takes a drum-shaped form within the main atrium space of the Phoenix Courthouse. It has translucent glass walls, sandblasted in such a way that moving shadows can be seen from the outer atrium space, hinting at the activity going on inside. The drum walls, laminated by Glasspro of Los Angeles, also use Butacite ® PVB interlayer for optimal security, safety and acoustics. Interpane of Clinton, North Carolina laminated the overall Courthouse roof, again with Butacite ® . Richard Meier told LGN: "This unique structure of laminated glass will be lit in such a way that it glows at night and can be seen like a beacon from great distances. We hope that it will become a central artistic symbol for the city of Phoenix."

Matt King summed up: "The special proceedings court is a fantastic space. You have the freedom of the open sky above, enclosed with the soft, diffuse glow of the walls and the lens. The traditional, authoritarian atmosphere of the older courthouses has been replaced with a feeling of lightness, accessibility, transparency – and beauty."