The taller the skyscraper, the longer the shadow. Walking along a street surrounded by big skyscrapers can feel like entering a world that’s permanently overcast–one reason most cities have zoning laws that restrict how high developers can build. But what if we could design a skyscraper that didn’t cast any shadow? That’s the idea behind a new concept by the architects at NBBJ, who used algorithms to create a tower that doesn’t block out the sun at ground level. Though specifically designed for London, where the next few years will bring a major influx of skyscrapers, the design could work in any dense urban area, where skyscrapers obscure the sun.
The no-shadow skyscraper is actually a set of twin towers that twist around each other. Their reflective facades are angled just-so to direct sunlight bouncing off one tower into the shadow of the other. The result, according to NBBJ’s calculations, is a 60% reduction in the shadows between the two buildings. There’s still some shade, but it doesn’t cloak the sidewalk in darkness.
Because of London’s location, the towers are wider at the top than at the base to take into account the changing position of the sun during the seasons. Since the sun is higher in the sky during the summer, the towers are broader so that the top floors can capture sunlight. For other locations in the world, the shape might look totally different to account for the climate. “In a hot [city] like Dubai, what you might do is modify the form so you have less reflection in summer,” explains Christian Coop, design director in NBBJ’s London office, so it could be narrower at the top, or angled away from the summer sun’s beams. Or it might have a slightly larger base to catch the rays of the low-lying sun during relatively darker winter days.
Sometimes, buildings can reflect too much sunlight (think of the Walkie Talkie melting a car or the Walt Disney Concert Hall heating up nearby residences). But Coop says that this phenomenon has been taken into account in designing the no-shadow tower. Unlike the Walkie Talkie, the reflective facades are not concave enough to create a magnifying glass effect, and there will still be some shade on the ground.
In tightly packed metropolises like New York–where new supertall skyscrapers have begun casting long shadows over Central Park–a design like this could balance the need for taller, denser housing options with the desire to keep ground-level spaces open and sunny. It’s the best of both worlds: enough light to keep the base of the skyscrapers from becoming a chilly wasteland, and enough height to please developers, without the need to trade air rights. NBBJ developed the idea for the architecture think tank New London Architecture.