In the midst of the Arizona desert in the US stands a half-built town that has attracted architects from around the world for the past 35 years. Arcosanti is an experiment in ecological city design. There are no cars since the space is planned for pedestrians, and there are large, compact living structures built next to huge solar-heated greenhouses where the residents’ food is grown. Electricity comes from wind and solar plants, and the water from the nearby river is carefully husbanded. Only 60 to 100 people live there now, well below the 5,000 that Paolo Soleri, the architect who founded Arcosanti, envisions. But since the project launched in 1970, 6,000 architectural students have come to help with the building and learn about its design, and the site attracts 50,000 visitors every year.

The aim of the town is to emphasise the benefits of city life and provide a contrast to endless sprawling suburbs built on the environmentally unfriendly model of “the American dream of single families with a car or two cars”, explains Mary Hoadley, Arcosanti’s site coordinator, who, with her husband and now her daughter, has lived there from the outset.

Gathering a greater density of people to live and work in one place not only benefits the environment, by requiring less expenditure of energy for things like heating and travel, but also allows people to feel part of a community. “The word civilisation comes from the same root as city,” Hoadley explains. And “living here is fantastic. We started with the energy of the 1960s but this is something that has stayed the course.”

Although the town is still less than half-built (“We thought we’d have built it in five years and then travel the world building more villages,” Hoadley explains, but capital proved hard to come by), Soleri’s ideas have been an inspiration to subsequent generations of architects. A retrospective of his work opened in Rome last month, and he will visit China shortly in order to explain his philosophy of “arcology” – a mixture of architecture and ecology – to government planners.

China may be the next centre for ecological city design since it needs to build the equivalent of several cities a year in the next decade to house its growing population while still protecting its natural resources from the effects of urbanisation and industrialisation. The government has realised that residents’ desire for a higher quality of life, with cars, washing machines and other modern conveniences must be balanced against the need to protect them from water shortages, smog and pollution and to prevent the desertification of former agricultural land.

In fact, the country is building the world’s first fully fledged eco-city in Dongtan, near Shanghai, on an island three quarters of the size of Manhattan that sits in the mouth of the Yangtse river, providing a home to thousands of rare birds, plants and other species in its wetlands. The contract for the planning of the city was awarded to Arup, the engineering consultancy, in August, and the company is tasked with making the city as close to carbon neutral as possible, replacing almost all of the environmental resources it uses. Renewable energy will be a key part of the plan, with energy coming from waste and combined heat and power plants. At present, most of the island is agricultural land.

By 2010, the first phase should be complete, and an exhibition will be held to showcase the development. Peter Head, a director of Arup involved in the project, thinks Dongtan sends a message that China’s government “is willing to find ways of overcoming the challenges of creating sustainable cities in the face of significant climate change, environmental pollution, water shortages and the need for the use of cleaner energy”.

Projects such as Dongtan aim to build on Arcosanti and show that whole cities can be environmentally benign, instead of dirty and damaging. But managing the lives of several million people in a way that respects the environment is a big leap from creating a small – unfinished – eco-community in the middle of the countryside or the desert. “When the economic reality sets in, and it looks as if these cities will cost more to build in the short term, short termism might take over and the environmental aspects will be forgotten,” warns Andy von Bradsky, director of PRP Architects.

Still, even if China doesn’t realise its vision of eco-metropolises, smaller towns and cities across the world are using Arcosanti as an example and taking steps to green themselves.

In the UK, Newcastle hopes to become “carbon neutral” by encouraging energy efficiency, generating electricity from renewable sources and planting trees. In the US, EcoCity Cleveland is helping its local government use eco-friendly principles. And in Germany, the eco-buildings of Freiburg in the Black Forest have made it a tourist attraction. “I don’t think you’d be able to sell a house in Freiburg if it wasn’t environmentally friendly,” says Bill Dunster, principal at Zedfactory, the UK architects.

Bo01 (pronounced Bo-Nol-Net), in Malmö, Sweden for example, is an eco-friendly district with schools, shops, restaurants, a park, a beachfront boardwalk and now more than 1,000 residents. Launched as a government project to revive the formerly industrial port along the Western Harbour it was named after 2001, the year it opened, and the Swedish word for dwell.

Housing ranges from single-family homes to a residential high-rise (architect Santiago Calatrava recently added a 54-storey tower called the Turning Torso) and all construction follows strict environmental guidelines. The energy comes from sun, wind and water, and residents’ electricity use is restricted to about half of what’s usual in Sweden; a large part of the town’s heat is extracted from groundwater.

“The idea initially was to get to grips with this old industrial land on the fringe of the city,” says Trevor Graham, project manager at Malmö’s environment department. “The concept was to create the city of tomorrow – a sustainable city marrying together quality of life, good architecture, good urban planning and environmental issues.”

In all these cases, architects and planners are giving up on the idea of an entire utopian eco-city and instead taking over an existing street by street or building up one neighbourhood at a time.