While many architects consider windows for brightening interior spaces, Norman Foster is intrigued by natural light from above. The British star architect has long held Louis Kahn and Alvar Aalto in high esteem for how they handled daylight - especially with regard to the roof. In particular large public buildings benefit from this strategy creating enjoyable spaces. Therefore, Foster regards daylight from above as indispensable when he develops megastructures for airports on the ground or tall skyscrapers for work. But daylight from above is much more than an aesthetic dimension, remarks Foster: "Quite apart from the humanistic and poetic qualities of natural light there are also energy implications."
At the time Foster designed Stansted Airport, typical architectural features of the typology included roof ductwork, suspended ceilings, roof-mounted air-conditioning units, and fluorescent lighting. In short, a lot of structural and servicing redundancy and very little natural light. By contrast, the roof of Stansted is unique."Its design is dedicated to natural light," explains Foster "with a proportion of the surface glazed to let sunlight in, and 'daylight reflectors' inside that bounce the light back up on to the sculptural shape of the ceiling. At night, artificial light achieves the same effect."
To achieve this, Foster turned the conventional terminal model upside down and placed all the heavy equipment underneath the main concourse."We were able to open up the roof to sunshine and light. The results were not just great savings in energy, but also a far more poetic spatial experience." He repeated this approach in later terminal projects, including the ones in Hong Kong or Beijing the roof lights played an integral role again.
Inspired by the images of the NASA Skylab with panels for energy harvesting, Foster went a technical step further for his high-tech project Hong Kong and Shanghai Bank. In order to collect more sunlight, Foster devised a scheme where the sun would be scooped into the base of the atrium and bounced off mirrors to of the high and deep building. Mirrors reflect the daylight through the translucent glass floor of the plaza to the ground. If no daylight is available anymore, he turns the concept back: "At night the situation is reversed by light glowing through from below so that the plaza floor itself becomes crystalline and jewel-like." Linking the idea of daylight from above for office buildings is not new like the Willis Faber building in Ipswich from 1975 demonstrates. For later headquarters, Foster mainly realized atriums without large dynamic daylight system, like the Commerzbank in Frankfurt.
The British architect has even looked into the underground for opportunities to bring down as much daylight as possible to enhance orientation and to create a natural atmosphere. The glass-covered entrances at the Metro in Bilbao and the Canary Wharf Underground Station draw the daylight deep into the concourse. His concepts started at the street level with glass escalators guiding downwards. The pools of daylight indicate the commuters the exit after leaving the train and reduce the need for orientation signage.
Although the old Reichstag in Berlin already had a dome to admit daylight for the chamber beneath, Foster's redesign of the dome fulfilled more functions. Offering a spiral walkway for the public was just one side aspect. Additional mirrors were individually adjusted to reflect horizon light into the space below for soft general illumination. But with so much daylight, glare control is a crucial issue. The large sun-shield in the dome offered the necessary visual comfort for the politicians and television broadcasting. The large element follows the path of the sun but blocks the harsh direct sunlight. At night, the mirrors in the cupola are used in the opposite direction to create a beacon of light as an urban sign. In addition, a ring of spotlights at the chamber ceiling took the direction of daylight up offering a fully controllable infrastructure for all functions and times.
What is fascinating about the difference between Foster's early and more recent projects is that one can now quantify cognitive aspects that were previously more qualitative. The physiological response to visually stimulating environments with natural light can be measured; increased patterns of blood flow would reach distinct zones of the brain. The ability to prove long-term performance increases has allowed the practice to justify higher invesment costs for a wide-range of high-end projects. The shift from viewing light as a qualitative asset to a quanitfiable resource has dramatically shifted the way the firm practices. As Foster remarks: "That humanistic, that poetic and spiritual dimension is for me completely wrapped up with the technology of how the building eventually 'breathes' and communes with nature."
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Light matters, a column on light and space, is written by Dr. Thomas Schielke. Based in Germany, he is fascinated by architectural lighting and works as an editor for the lighting company ERCO. He has published numerous articles and co-authored the books “Light Perspectives” and “SuperLux”. For more information check www.erco.com, www.arclighting.de or follow him @arcspaces.