How A Game-Changing Architectural System Can Turn Buildings Into Solutions To The Climate Crisis

The Agora Cancer Research Pole in Lausanne, Switzerland, Adidas World of Sports Arena office in Herzogenaurach, Germany, and Harvard University Science and Engineering Complex in Allston, Massachusetts, showcase German architectural firm Behnisch Architekten’s groundbreaking external fixed sunshade system. While many façades have been covered with fixed lamellas, what’s highly innovative about Behnisch’s system is the precision of design in having the grid structure adjusted across the entire surface to perfectly respond to the building’s façade inclination, location, orientation and environment. Depending on its exact position on the façade, each screen is precisely dimensioned and machined. All three projects were the result of an elaborate study of sun angles specific to each climate, with the shades of each façade more pronounced at particular angles. Not only was technical performance pushed to the limits, but also how these screens are experienced from the inside and how these façades impact the public realm. Michelle Lee, architect at Behnisch Architekten, shares her thoughts.

What is so special about the world’s first hydroformed tensile façade system used in the Harvard University Science and Engineering Complex? What resources and raw materials have been used for this hydroformed tensile façade system, and how have they been used or made?

I do not believe we could have achieved this façade design using traditional architectural fabrication processes (i.e., folded metal). Firstly, we had 12,000 panels with 14 different shapes, which speak to scale that must bridge customization and mass production. Therefore, Josef Gartner, our façade contractor, decided to search outside the traditional confines of architectural fabricators. They took us to meet a local stainless steel fabricator outside of Stuttgart that specializes in automotive parts and industrial cooking equipment, but had never produced a building component. They had a hydroforming machine that they said could make our components on budget and on time and potentially reduce the thickness of the material. The cross-disciplinary nature of this research endeavor, in which both parties had to learn from each other, is what made this process special. In the end, the hydroformed method resulted in raw materials savings of 90 % in embodied carbon compared to the folded aluminum shades of Agora Cancer Research Pole and Adidas Arena.

Each façade shading panel is made from a single 1.5-mm thick stainless steel sheet, which measures 3.5 square feet. The stainless steel is made in Germany from 90 % recycled content. 3,000 bars of pressurized fluid are used to push the stainless steel sheet incrementally into a negative stainless steel mold. After forming the panel, it looks a bit like the inside of a sink or dishwasher. This shape is then annealed in order to release the stress of the molecules. A five-axis laser cutter cuts the final shape, and then perforates around 100 holes along the edge of the panel in order to feather out the edge and reduce glare and contrast. Finally, the stainless steel panel is finished with ceramic bead blasting to give a mat, high-quality finish. We wanted the panel to not only perform, but be beautiful and capture the qualities of the sunlight as it touches the folds and curves of the panel formed by water.

How would you retrofit existing buildings with the new external fixed sunshade system?

There is a good example of this in Singapore called Centennial Tower, which was designed by Kevin Roche and then retrofitted by Morphosis. However, the metal shades here are more driven by composition than by performance. One technique we used for Harvard was a spring-loaded tensile system, which would be very beneficial for retrofitting façades. The structural anchoring happens at the top and bottom of the façade, and the tensile spans at each level, which minimizes penetrations and coordination through the existing envelope.

You developed the external fixed sunshade system to be adaptable to any city in the world, to buildings of all sizes and types. How do you envision the external fixed sunshading being applied in Asia? How would the buildings in Asia with this system be distinct from those built in the West?

Asia is a big place and encompasses almost every climate and landscape imaginable. But as home to some of the most populous, densest, most vertical and fastest growing cities on the planet (Shanghai, Beijing, Tokyo, Shenzhen, Manila), the use of sunshading would be commensurately more impactful. However, this has to be designed in conjunction with a sound window wall design. You cannot design a 100 % glass facade and throw sunshades on it and call it sustainable. Glazing has to be allocated in a thoughtful way to allow for views and optimum daylight, then sunshades are applied on top to improve further. Another unique aspect of façades in Asia concerns building density and the heat island effect. As home to some of the most rapidly urbanizing societies, the material choice must deal with this issue. When blocking and rejecting the sun’s energy, we must ask: where are we transferring this energy? How can we redirect this solar energy away from the interior of the building, but not have it contribute to the urban heat island effect? We have to think of the impact of our façade outside of the traditional confines of the building, especially in dense and hot Asian cities, whose density and peak temperatures will only grow in the future.

In Asia, the architectural materiality of sunshading has enormous potential for exploration. We believe that by leveraging the unique regional knowledge, cultural and material assets and the technological innovation in the region, new solutions and innovations will outperform a design that is “imported”. To be specific, shading materials that would make sense in China would be local terracotta, porcelain and bamboo, as there is a longstanding artistic tradition in working with these materials that dates back thousands of years. The material and construction system should make the most of the assets of the region and be tuned to the solar angles and site context using a combination of local knowledge, digital software and CNC fabrication. This combination of thinking and research would yield fruitful new examples and strategies to deal with climate change that are specific to each location and enrich the global repertoire of façade design.

Since the geometry of the fixed sunshading is the basis of efficiency and we have shown that you can achieve the same effect with quite different and very distinct forms and materials, this method and concept open a richness of different geometrical and material approaches. Movable Venetian horizontal blinds look almost all the same nowadays. When closed, the buildings all look alike, or at least most, no matter where they are. With the fixed geometrical sun protection, each solution in different places looks slightly different by default. Meteorological, geographical and cultural aspects will drive the solution and appearance and express themselves.