The south side of the 56th floor of the Willis Tower is being fitted with solar windows (Image: Harshil.Shah via flickr)
Chicago's Willis Tower, formerly known as Sears Tower, was the world's tallest building from 1974 to 1998 and remains the tallest building in the U.S. to this day. Its 1451-foot (442 m) height adds up to enough window area to keep a window washer busy for life, or space for enough solar panels to be comparable to a 10 acre solar power plant. As part of a pilot project, the south facing windows of the 56th floor of the Willis Tower will be replaced with Pythagoras Solar's transparent solar windows which cut down on heat gain – and therefore cooling costs – as well as harnessing energy from the sun.
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