The Use of Extruded Concrete in Rainscreen Applications
Conclusion
Extruded concrete is quickly becoming a popular choice in rainscreen assemblies, outperforming the other concrete-based options in several categories. Rainscreen panels made from extruded concrete layered with glass fiber can be rapidly produced, and the finished product combines many of the desired attributes for quality rainscreens. Specifically, the panels are thin, lightweight, and strong but also durable and noncombustible. Available in a range of colors and surfaces, the material gives architects a wide range of design choices—not just for rainscreens but also for creating architecturally dynamic facades.
EXTRUDED CONCRETE PANELS
© Ditz Fejer
Location: Boston
Architect: Payette
Project: Center for Integrated Life Sciences and Engineering at Boston University
The Center for Integrated Life Sciences and Engineering, located on Boston University’s Charles River campus, serves as an interdisciplinary research facility. Designed by Payette, it’s the university’s first research building to face directly onto Commonwealth Avenue; consequently, it presented designers with an opportunity to create a building that is both distinctive and pays homage to the historic structures surrounding nearby Marsh Plaza.
Payette’s designers felt that a purely glass facade for the nine-story building would be too commercial for the urban campus. The addition of glass fiber-reinforced concrete fins introduced an organic facade element that could also be used for shading.
The design team selected a glass fiber-reinforced concrete material for the sandstone-colored facade elements. Just 13 millimeters thick, the material comes in a variety of colors and easily can be formed into panels with complex geometries.
The north and west public sides of the CILSE building are defined by a vertical pattern of projecting concrete fins, which enhance the glass facade. The 1,300 U-shaped elements are supported by an integrated fastening system, which allowed for quick assembly and installation. Because the structural anchors were premounted, the formed parts simply could be hooked to the substructure and fine tuned. The light weight of the concrete elements also reduced the amount of material required for the substructure.
The character of the dynamic facade changes depending on the viewing angle, appearing both opaque and transparent at the same time. From a distance, the glass is “hidden” and the building appears to be made of solid concrete panels; closer in, the concrete fins “disappear” and the reflective glass surfaces emerge. The cantilevered concrete fins also function as sun protection.
On the east and south sides, flat extruded concrete panels alternate with narrow glass windows—an inversion of the pattern on the other facades.
CILSE is designed to be 29 percent more energy efficient than a similar code-built structure. Payette is seeking LEED Gold certification for the project.
EXTRUDED CONCRETE PANELS
© Ditz Fejer
Location: London, Great Britain
Architect: Sheppard Robson Architects
Project: citizenM Tower of London Hotel
The Tower of London Hotel is the newest addition to the citizenM hotel chain. Consisting of 320 hotel rooms arranged around a central courtyard, the new building is located in a complex urban and historically rich setting, close to both the Tower of London and adjacent the remains of the city’s Roman wall.
The architects from Sheppard Robson were tasked with balancing the design so that it reflects the hotel chain’s trademark aesthetic while being sensitive to the historic surroundings. While many citizenM hotels feature muscular dark grids that frame the glazing in regular units, this building incorporates Portland stone, glass, aluminum, and dark gray formparts to create a more open, organic look.
The nine-story building is broken into four horizontal sections that reduce the massing and help the building integrate with its surroundings. The Portland stone framing breaks the facade into five equally sized vertical rectangles, while slender aluminum extrusions divide the facade horizontally at each floor level. The irregular arrangement of the dark fins against the glass combines to create a disciplined yet modern aesthetic.
The formparts are made from fiberglass-reinforced concrete and are finished with a luce coating, which catches the light and subtly sparkles depending on the viewing angle.
The 570 U-shaped formparts were fitted with corresponding stainless steel brackets on the ground before being lifted into place. The team was able to develop a cost-efficient solution for the installation of the formparts that also met the tight schedule.
In addition to contributing to a dynamic facade, the vertical fins also provide shading and helped the building earn a BREEAM Excellent sustainable rating.
Completed in 2016, the 12,822-square-foot building is a welcome addition to its historic setting in the heart of London.
Andrew A. Hunt, is vice president of Confluence Communications and has been a writer and consultant in the green building and building science industry for over a decade. He has authored more than 100 continuing education and technical publications as part of a nationwide practice. www.confluencecommunications.com
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The diversity and high performance of fibreC glassfibre reinforced concrete allows for cost-saving construction of high-quality, cutting-edge facade systems with long-term durability. It is authentic and in line with the current trend toward natural and sustainable materials. www.rieder.cc/us/en/ |
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