Material innovation is essential to creating beautiful, campus-friendly energy facilities while satisfying the demanding performance requirements of industrial enclosures.
Leers Weinzapfel’s competition-winning design for the University of Pennsylvania Chiller Plant called for an elliptical screen wall that possessed a curvy elegance of form, shimmered and disappeared by day, and by night transformed into a translucent glowing object, partially exposing the equipment within. The screen material also needed to permit free air circulation, be resistant to steam-induced corrosion, resistant to vandalism, resistant to high-impact abuse, safe to touch, maintenance-free and economical.
That strong, beautiful, breathable, cost-effective material did not yet exist.
To develop a new screen material for the UPenn chiller façade, the LWA design team leveraged years of experience testing and implementing windscreens for transit projects, including railroad platforms on the MBTA commuter rail lines. The first perforated sheet stainless steel was developed for commuter railroad platforms on the Old Colony (now known as Kingston/Plymouth) line, and then used subsequently on Newbury line stations. Windscreens allowed visibility for safety but provided sufficient density for wind protection and to withstand potential passenger abuse. Prototype structures with different size openings were tested by MIT’s Wright Brothers Wind Tunnel project. This perforated sheet stainless steel served as the precedent for the competition-winning design.
During design development, the LWA team worked closely with the fabricator – Centria – to find the most effective material for the most affordable cost. Aluminum offered a compelling alternative to stainless steel from a price perspective. However, the thriving scrap metal market for aluminum created a new challenge – designing a vandal-resistant attachment system.
Mock-ups for both stainless steel and aluminum panels were tested. The team developed a unique shoe to secure the aluminum panels against both movement and vandalism. Although both materials were well-secured, ultimately the aluminum panel did not pass the test for high-impact abuse. The chiller plant is nestled within a broader landscape of recreational facilities, immediately adjacent to softball fields. The aluminum panels were easily damaged by errant balls – refocusing the design effort once again on stiffer stainless steel.
Perforation and Corrugation
Several variations of panels were developed with various perforation sizes to balance open area with material presence. For safety, the hole size needed to be small enough that a small child’s finger couldn’t fit in it. Although perforating the panel was effective in reducing material weight, it also impacted stiffness. Ultimately, the perforated panel was corrugated to increase structural effectiveness.
LWA and Centria developed perforated and corrugated panels utilizing 20 gauge stainless steel and 0.040″ painted aluminum. The result was a panel with a 40% open area that provided an airy aesthetic that controls light and air movement. The corrugated panels were installed vertically to form a sixty-foot high screen-wall, attached to a steel framework laterally braced to the equipment building.
The result is known today as Centria Eco Screen Eco Lap ¾”.
The screen wall around the chiller plant celebrates the industrial nature of the structure and veils the building, making it a shimmering, silvery object by day crowned by rooftop cooling towers. By night, the building becomes a translucent glowing object, revealing the colorful equipment within.