Plugging into a sustainable culture is not just about travelling by bus, having a shower instead of a bath and recycling your newspapers. According to Herbert Girardet, key speaker at Ove Arup's conference on sustainable cities last week, it can also be a profitable business.
He describes himself as a cultural ecologist, and recalls when his interest in sustainability began during the 1970s. 'Lots of people were building small windmills and talking about wind power as the energy for the future, but it wasn't taken seriously in the UK,' he says.
Development money was put into nuclear energy, he adds, leaving it to the Dutch and the Americans to take the lead in wind power. 'Now, when you see wind farms in the Welsh countryside,' Girardet explains, 'it's all imported technology.'
Girardet's interest in sustainability was sparked by genuine concern. He was working as a journalist and documentary film maker and was studying the impact of humans on the environment, particularly in the Amazonian rain forests.
Now Girardet is something of a guru on sustainable urban development - and how administrators, planners, architects and engineers can help to achieve it. He was awarded a UN Global 500 award for outstanding environmental achievements at the 1992 Rio Earth Summit.
In the 1970s, he says, the ideas were around and journalists were writing about sustainability issues. 'But at the time we didn't have the facts and figures, especially about job creation and the economics of sustainability,' he adds.
One of key aims in developing a sustainable city is to reduce its 'ecological footprint' - the land surface required to feed it, supply it with timber and re-absorb its carbon dioxide output. London, for example, with 12% of Britain's population, has an ecological footprint which covers the equivalent of Britain's entire productive land.
Making a city more self-sufficient can reduce this footprint, for example by encouraging urban farming, recycling sewage and composting waste. Traditionally cities had a circular metabolism and produced their own resources and re-absorbed their own wastes. But today's cities have a more linear metabolism, sucking in produce from all over the world and sending out waste for disposal elsewhere.
No single city can be held up as an example of sustainability, says Girardet, but there are many which have a particular expertise.
Vienna has the highest level of recycling in Europe and also has extensive urban farming; Copenhagen has the best examples of combined heat and power schemes; Zurich's tram system is a model for public transport. Even in Britain we are not bad at recycling, he admits.