The Estádio Nacional de Brasília, a soccer stadium in Brazil's capital is undergoing $400 million worth of upgrades and could become the world's first net-zero-energy stadium. The 70,000-seat facility is aiming for LEED Platinum and was designed by Castro Mello Architects using Autodesk software. The stadium's roof will boast a photocatalytic membrane that collects falling air pollution, breaks down the chemicals in the pollution and takes them out of the air.