From WIRED:
Growing cities around the world have nowhere to go but up, leading to taller and taller buildings. But while mega-skyscrapers are the most efficient way to build new homes, they also cast long shadows, drawing the ire of people living and working below. One solution: a pair of buildings that work together, reflecting sunlight to minimize shade.
About 250 skyscrapers are slated to redraw London’s skyline in the near future—each with its own dark imprint on the streets below. So architects at the firm NBBJ in London decided to see if they could come up with an entirely shadowless building. They used computer modeling to design a pair of buildings, one of which works like a gigantic, curved mirror. The glass surface of the northernmost building reflects light down into the shadow cast by its southern partner. And the carefully defined curve of that glass allows the reflected light to follow the shadow throughout the day.