Dongtan was presented at the United Nations World Urban Forum by China as an example of an eco-city (it was purposely built), and is the first of up to four such cities to be designed and built in China by Arup. The cities are planned to be ecologically friendly, with zero-greenhouse-emission transit and complete self-sufficiency in water and energy, together with the use of zero-energy building principles. Energy demand will be substantially lower than comparable conventional cities due to the high performance of buildings and a zero emission transport zone within the city. Waste is considered to be a resource and most of the city's waste will be recycled.