Innovations in Light and Sound

Architects explore the aesthetic side of acrylic building materials

While plastic building products are often cited for their energy efficiency, durability, and cost effectiveness, their ability to produce eye-catching designs is sometimes overlooked. Similarly, some design/construction professionals do not consider the acoustic properties of certain modern materials. But the idea that plastics can provide striking visuals was not lost on the U.S. General Services Administration (GSA), the organization charged with maintenance and operations of the nation’s federally owned buildings. The GSA helps federal agencies better serve the public by providing government employees with effective workspaces. During an asset audit, the organization decided to modernize a portion of a 99,406- m2 (1.07 million-sf) warehouse within the Bannister Federal Complex in Kansas City, Missouri. The GSA requested a redesign strategy as creative as it was cost-effective—and plastics answered the call.

Radiant thinking for the GSA

A fundamental element of the GSA’s plans was to create a naturally lighted public atrium that would brighten and open up any new office facilities adjacent to the renovated area. To diffuse light from the new space as far into the surrounding spaces as possible, BNIM Architects (Kansas City, Missouri) proposed a dynamic lightmediating sculpture that harnessed the color-changing properties of a proprietary acrylic.

When BNIM approached the Bannister project, its goal was to devise a unique, efficient, and environmentally responsible solution to the large building’s low-light problem. The new, angled, sky-lit atrium provided an abundance of natural light while also maintaining the building’s design integrity. The light-mediating sculpture was devised to boost and spread the natural light’s effect, serving to add vibrancy, color, and flare to an otherwise drab, warehouse-like interior. It was a welcome addition, according to GSA deputy regional administrator (Heartland) Jim Ogden.

“Our World-War-II-era facility was in need of some updating,” he explains. “We needed a way to break up the abundance of warehouse space, and the atrium, skylight, and sculpture sounded like the perfect solutions.”

Ingenuity in design

BNIM designed the light-mediating sculpture to be a permanent building fixture. Suspended from concrete beams within the framework of the skylight, it integrates light, color, and form into the motif of the building.

“As a former warehouse, the building was inappropriate for office space,” says Curtis Simmons, a BNIM project designer. “We developed the atrium design with the intention of giving office tenants and visitors a sense that time is changing throughout the day through the direction and intensity of light and shadow.”

The radiant acrylic sheets enhanced how the light sculpture provides this sense of change. The plastic products’ specially treated surfaces allow them to reflect light in a way that produces a visual shift through the color spectrum when viewed from different angles. As the sun alters its position through the day as well as the year, BNIM’s light sculpture produces a myriad of dynamic light effects.

“The transitioning colored light produced by the acrylic sheet lends a sensation of time, rhythm, and movement to the previously listless space,” says Simmons.

The striking yet simple-looking light sculpture applies complex architectural principles. Exhibiting advanced geometries dominated by compound curves, the sculpture presented unique challenges during fabrication. For example, the aluminum tubing constituting the sculpture’s skeleton had to be twisted and bent simultaneously to attain the appropriate curvature of the design. The radiant acrylic sheets were more adaptable than some other semi-transparent materials because they provided a better balance of rigidity and flexibility at the thickness employed.

“The plastic sheet was ideal because, even though it was rigid, it was able to conform to the sculpture’s curvature,” explains Simmons. “As an added bonus, when we pin-connected the acrylic to four corners, it created a kind of unpredictable—yet beautiful— undulation in the sheet. It exuded a more organic feel than what the stiffness of more traditional materials would have achieved.”

The durability of the radiant sheet facilitated and expedited fabrication of the light sculpture. With the possibility for higher levels of impact resistance, the lightweight acrylic sheet withstood drilling and installation without requiring the work of a structural engineer. Acrylic can also be more economical and can adhere better to other materials—two advantages critical during the sculpture’s complex construction.

As construction for the building’s new office space comes to a close, the GSA project managers are pleased with the modernized space. The renovated atrium has also been popular with the Bannister tenants, who have sometimes changed their daily lunch routines to incorporate a visit to the atrium’s colorful serenity.

An earful of benefits

Acrylic plastic products have also achieved success in a very different sort of project—controlling highway noise for residential communities.

Since the first homes in the Aegean Hills residential community were built more than 30 years ago in Mission Viejo, the California Department of Transportation (Caltrans) has implemented numerous road work projects to support the growing population in Orange County.

After one of these recent efforts greatly expanded a section of the I-5 freeway located directly behind Aegean Hills, Caltrans and the Orange County Transportation Authority (OCTA) chose a unique option to shield the neighborhood from increasing traffic noise— building an approximately 488-m (1600-ft) long transparent sound wall along the residents’ backyards. The first of its kind in California, and the first Caltrans noise-reductive barrier constructed on private property, this transparent barrier allowed the 34 Aegean Hills homes to be spared the noise of the freeway and the obstruction of a concrete wall blocking the community’s treetop views.

Caltrans, OCTA, and the City of Mission Viejo worked closely with the Aegean Hills Homeowners Association (AHHA) in developing a plan to construct the transparent sound barrier. Tasked with engineering this project, a Southern California civil engineering firm, Willdan, designed a distinctive noise barrier that combined standard concrete masonry unit (CMU) blocks with new soundinsulating acrylic sheets.

Special solutions for special situations

When the El Toro Y expansion project was launched in the early 1990s, a noise abatement policy was included to protect bordering residents from increased highway noise. Since 34 homes within the Aegean Hills community were located on a hill within close proximity to the freeway, the majority of the land between the houses and the freeway was privately owned, rendering the community ineligible for publicly funded sound walls. However, in 1998, Caltrans implemented policy changes that allowed for government funding of freeway noise barriers on private property under special circumstances. Included within these changes was a stipulation—funding could only be granted if 100 percent of involved residents agreed to a construction plan.

To develop a solution acceptable to all involved homeowners, AHHA surveyed residents in other local communities that had installed standard concrete block walls near homes.

“Some people we spoke to were unhappy with their concrete noise walls,” says Karen Caiozzo, an Aegean Hills resident. “The walls successfully decreased the sound coming from the highway, but the residents’ backyards were very dark and depressing. They said that plants wouldn’t grow, and they were spending less time in their backyards. We knew we had to find another solution for our community.”

After Caiozzo researched alternative Caltrans-approved sound wall materials, she found that acrylic panels exhibited many of the qualities her community desired. Providing sound abatement for roads and bridges around the world for the last 30 years, the noise barrier material also offered the opportunity for better than 92 percent light transmission.

The plastic panels are lightweight and weather-resistant, while also offering a degree of ultraviolet (UV) stability to help maintain long-term clarity. Additionally, the material’s availability in various thicknesses allows its noise reduction properties to be tailored to many different types of projects.

Design and implementation

For the Aegean Hills project, Caltrans and OCTA regulations required a structurally sound and cost-effective noise barrier that would reduce the incoming freeway sound by at least 5 dBA. The city of Mission Viejo turned to Willdan to develop and engineer a sound wall from the acrylic panels that met these requirements.

Willdan engineers worked closely with the product’s manufacturer to gather information on the sheets’ noise-reduction abilities. After learning that a 12.3-mm (0.5-in.) thickness of the material would meet the noise abatement requirements, Willdan designed a 4.3-m (14-ft) high sound wall with the appropriate stacked noise barrier panels, situated atop a 1.2-m (4-ft) high CMU wall.

Willdan’s design meets the conservative criteria of the 1997 Uniform Building Code (UBC) and can withstand wind speeds of up to 129 km/h (80 mph) and earthquake vibrations stemming from the nearest faults. This solution quickly attained 100 percent approval from the affected Aegean Hills residents and earned OCTA funding.

RMF Development Co., a San Diego, California-based contracting firm specializing in the installation of transparent sporting spectator shielding, was chosen to install the noise barrier panels. RMF worked with Willdan and the acrylic product manufacturer to devise a framing method that would support the panels while facilitating the installation process.

“Using a system comprising masonry columns, steel angles, and rubber gaskets, we were able to secure the stacked acrylic panels in a steel frame so there was a tight positive connection between the columns and panels,” explains Eric Johnson, a Willdan project manager.

The lightness and durability of the acrylic panels greatly facilitated the installation.

“It was very simple for our contractors to work with the panels,” says Rick Frisby, the owner of RMF. “In addition to providing great clarity and sound protection, they are relatively light to handle. This attribute made the panels much easier to handle, manage, and move during installation.”

Seeing through the results

The transparent sound wall has been a welcome addition to the Aegean Hills community, reducing noise by 8 to 12 dBA—greatly exceeding the 5-dBA requirement. Since sound almost doubles for every 10-dBA increase, the final result effectively cuts the noise in half. The noise reduction has greatly enhanced the residential experience for the 34 affected homeowners, allowing them to enjoy spending time in their backyards for the first time in more than a decade.

“We could tell while we were installing the sound wall many Aegean Hills residents had not been using their backyards prior to this project,” says Frisby. “When the wall was completed, people started mounting small fountains, planting gardens, and even installing hot tubs. A woman who had been living there for more than 20 years thanked us because now she could invite her ladies group to have tea in her backyard and carry on conversations.”

As California’s first successful implementation of a publicly funded noise barrier project on private property, the Aegean Hills sound wall serves as a model for other noise-afflicted neighborhoods and has spurred interest throughout the state. For example, Laguna Hills and several other cities in Orange County and the San Diego area have contacted Willdan and RMF for similar projects.

“The Aegean Hills transparent sound wall was an innovative solution that has allowed public agencies to successfully meet the needs of their community members,” explains Johnson. “Thanks to the strength of the partnership between all involved parties, the project’s success will serve to modernize noise abatement practices in the region and throughout the state of California.”