Perforated Panels Renew Library
Double-layered sunscreens create dynamic interior
Patterns can become part of a
building's identity. At Rinconada Library in Palo Alto, Calif.,
circular and T-shaped elements are incorporated throughout. On a
macro level, the building's footprint is T-shaped. Zooming in,
terra cotta sunscreens with a grid of bisected circles enclose
courtyards on three sides. The same circular pattern on the terra
cotta is repeated on light panels in the interior. Additionally,
there are round pedestal gardens and a large, circular planting bed
on the site.
When it came time to renovate and expand the library in 2013,
South San Francisco, Calif.-based Group 4 Architecture, Research
and Planning Inc. picked up on the circular pattern to develop
double-layered, perforated aluminum sunscreens.
The custom sunscreens met several goals. In addition to the
practical need to shield intense sunlight, the project had to be
sensitive to the building's original design. Edward Durell Stone
designed the library, then called Palo Alto Main Library, for
construction in 1958. Group 4 was tasked to develop a plan that
complemented Stone's design and differentiate the new parts.
In plan, the historic wing forms the top of the T, oriented
north-south. The addition extends east, forming the stem of the T.
The project expanded the library approximately 4,000 square feet,
bringing it to 30,000 square feet. When the LEED Silver-certified
project was completed in February 2015, it was renamed Rinconada
Jonathan Hartman, LEED AP BD+C, principal at Group 4, says,
"Reflecting on the role of the patterned terra cotta block
screenwalls around the existing building and their role in light
control, we started thinking about a patterned screen that was
elevated above the ground plane to preserve views into and out of
the building, while helping to control high-angle solar exposure.
Both the historic and new wings of the expanded library feature a
new translation of the circle pattern's geometric language."
Mokena, Ill.-based Architectural
Grilles and Sunshades Inc. (AGS) fabricated, and Hayward,
Calif.-based Capitol Glass Co. installed, Newnan, Ga.-based Bonnell
Aluminum Extrusion Co.'s aluminum into 3/16-inch-thick panels with
water jet-cut perforations for the double-layered sunscreens. The
panels were powder-coated to match the Atlantic Gray of Norcross,
Ga.-based Kawneer Co. Inc.'s storefront windows. Additionally, AGS
fabricated 2-inch by 6-inch rectangular aluminum tube spacers and
1-inch diameter stainless steel stand-offs for the project.
"From the beginning, we felt that the screen wanted to have a
depth to it and we liked the interplay of two layers working
together to create a sum result that was far greater and richer
than what you experienced with each layer independently," Hartman
To come up with the optimal perforations, Group 4 completed
numerous studies including a scaled model of the final option and a
full-scale mockup of a panel face. "We explored a wide variety of
patterns, pattern densities and screen heights before arriving at
the final solution," Hartman says. "The iterative process was
essential in honing in on the right size and scale of the circles
and their relationship to each other between the two faces of the
screen. The circle pattern in each layer is based on a custom
algorithm designed to create dynamic shadows inside the space that
mimic the quarter circles of the historic terra cotta screen."
Special consideration was given to
installation. Capitol Glass bolted the panels to the sloped,
primary steel structure with custom brackets. "In the design of the
mounting brackets, we anticipated the need for field adjustments at
each bracket to address construction tolerances between the primary
structure and the screen, which ended up working very well,"
Hartman says. "In the new wing, the sunscreen runs horizontally
around the eaves, suspended to a level aligned with the top of the
historic terra cotta walls. This creates a floating-roof effect and
a complementary architectural composition with the historic
The aluminum panels required hidden slip joints to accommodate
thermal expansion across the continuous length of the south-facing
span. "In the historic wing, the dual-layer metal sunscreen is
suspended from the eaves in a vertical orientation to screen the
new glass-enclosed group study rooms," Hartman says. "In this
location, the sunscreen comprises de-mountable panels to permit
cleaning of the exterior of the glass. Additional rigidity was
required for the screen in this application, as well as standoff
supports incorporated into the window wall structure."
Rinconada Library, Palo Alto, Calif.
Owner: City of Palo Alto
Architect: Group 4 Architecture, Research and
Planning Inc., South San Francisco, Calif., www.g4arch.com
General contractor: SJ Amoroso Construction Co.
Inc., Redwood City, Calif., www.sjamoroso.com
Glazing/sunscreen installer: Capitol Glass Co.,
Hayward, Calif., www.capitolglassco.com
Fabricator: Architectural Grilles and Sunshades
Inc. (AGS), Mokena, Ill., www.agsshade.com
Aluminum: Bonnell Aluminum Extrusion Co., Newnan,
Storefront: Kawneer Co. Inc., Norcross, Ga., www.kawneer.com
Photos 1, 2: Cesar Rubio,
Photo 3: Courtesy of Group 4