Published March 24, 2017
A golf ball can travel farther because of the dimpled surface that allows it to slice through wind.
Imagine a similar principle applied to the exterior of a high-rise building. Only in this case, the design element of textured skin integrated with the main structure makes the building stiffer and helps the building alleviate wind load. This, in turn, makes the building more environmentally friendly by requiring less energy and cutting back on the amount of steel needed during construction.
That’s the idea a UB architect presented for his design as part of an international competition. The challenge for participants was to develop a tower design that contributes to more environmentally friendly high-rises. It’s an issue architects around the globe have begun paying greater attention to as more people live in landlocked urban areas where the only way to build is up.
Jin Young Song, assistant professor of architecture in the School of Architecture and Planning, teamed up with Donghun Lee, a PhD candidate in the School of Engineering and Applied Sciences, and technical designer and structural engineer at Skidmore, Owings & Merrill, to develop a building skin that can increase the stiffness of the tower and alleviate wind load better than the traditional flat exterior many high-rises have employed since the birth of the Chicago School skyscraper architecture in the late 19th century.
Their project, called Emboss Tower, was one of six finalists in Metal in Construction magazine’s Meeting the Architecture 2030 Challenge, an architectural design competition created to help solve the world’s climate crisis.
“The industry is changing. There have been a couple of measures of a building’s sustainability — LEED certification, for example — but now architects are interested in creating an additional measure, one that looks at the embodied energy calculation of a building in design phase,” Song explains.
Competition entries had to integrate a high-rise building’s enclosure with its structure. The idea was to substitute the standard aluminum and glass curtain wall system with a hybrid frame and skin structure. Entries were judged on the amount of embodied energy reduced in the form of building mass, as well as on the overall performance of the enclosure.
“Our design represents more than a cosmetic change to tower design. It is a more fundamental function of skin,” Song says. “The design is 10 percent stiffer than a flat building, the interior space is more versatile and it’s aesthetically pleasing in the city,” he adds. “We eliminated the conventional use of an aluminum curtain wall because we will have a secondary steel structure in the diagrid system.”
That matters, he says, because aluminum production is non-structural and uses much more carbon dioxide than steel.
In their design concept, Song and his team explore the function of structural skin through a curved, embossed surface that enhances the tower’s stiffness. To make the building laterally stiffer, the curved form integrates with the diagonally intersecting steel system — known as a diagrid — and the embossed surface around the diagrid. This design “confuses” the major wind, which reduces wind pressure on the building. In the tall tower design with increasing height, wind engineering of dominant lateral loading governs the design factors to secure structural strength and user comfort.
That’s where Lee, the PhD student, came in. Lee conducted several analyses that showed that the Emboss skin functioned better than a flat tower. “His structural analyses gave me positive feedback that this design was practical and possible,” Song says.
With the Emboss design, function of the building envelope has been reimagined with a more holistic role within the building’s systems, according to Song. The design shifts attention from the envelope serving exclusively as a climate barrier and façade. Instead, it serves as an integrated system that enhances the building’s presence and efficiency through features unique to its form.
Now that the Emboss design has fared well in international competition together with other entries from global firms and academia, such as AECOM, HOK, ODA with Werner Sobek, EYP and TU Delft, Song plans to continue researching its design functionality and publish the findings in a journal. He is working with collaborators from New York-based Skidmore, Owings & Merrill, among others, on the research paper.