The Crystal, in London, a Sustainable Cities Initiative by Siemens, offers a fossil fuel free vision of the future. It is an all-electric building that uses solar power and ground source heat pumps to generate its own energy. It also stores electrical energy in a giant battery to ensure excess power can be saved for use when supply is low. The building incorporates rainwater harvesting, black water treatment, solar heating and automated building management systems. The design of the building’s structure, including its glass, provides additional insulation, helping it achieve Leadership in Energy and Environmental Design (LEED) Platinum and BREEAM Outstanding ratings.