It is an unlikely alliance: Germaine Greer, Sir Simon Jenkins, Dame Judi Dench, Richard Rogers, Ben Fogle, Duncan Goodhew, John Nettles and the family of Tim Henman united at the barricades. But then, eco-towns are an unusual opponent, forcing together those who you would expect to oppose them with those you wouldn't.

A YouGov poll in June showed 46 per cent of the public in favour of building eco-towns, with just 9 per cent opposed. Yet there's no disputing the strength of local protest at many of the 13 sites on the Government's shortlist. One group, the Bard campaign, which opposes an eco-town outside Stratford-upon-Avon, has called for a judicial review of the consultation process. Already two from the original shortlist of 15 - Lincolnshire and Staffordshire - have dropped out.

When Gordon Brown announced plans for eco-towns in May last year he was trying to seize the green initiative back from the Conservatives. Brown reiterated the Government's plan to build 3 million new homes by 2020. The problem had always been the vast increase in Britain's carbon footprint that this would entail.

On paper, the latest standards for eco-towns, set down two weeks ago by Housing Minister Caroline Flint, are the epitome of moderation. Ten are to be built, defined by the Government as having between 5,000 and 20,000 homes, built to at least level four of the Code for Sustainable Homes (the Code measures the sustainability of a new home against nine categories of sustainable design). These towns would include at least 30 per cent affordable housing, “high-quality public transport links” and enough community facilities and jobs to avoid them becoming commuter 'burbs. Each would be an exemplar in eco-design, with all buildings achieving zero-carbon status. The average home would be within ten minutes' walk of frequent public transport and everyday neighbourhood services.

Shoddy design, that curse of so much British housing, would be avoided with “a commitment to high standards of architecture”, an architectural competition in each town, and designs overseen by various professional bodies. The Housing Minister at the time, Yvette Cooper, promised “a mix of styles” not “the grand vision of a single architect” that still blights many of the postwar towns. What's not to like?

“On the whole it's a good thing,” says Bill Dunster, the designer of the UK's largest carbon-neutral development, BedZED in South London. “It's very clever, because it instantly creates a market for carbonzero homes. Left alone, housebuilders would move slowly to meet the new green housing standards. This, though, is like rocket fuel to the cause.”

The protestors would beg to differ. Yet beneath some of the nimbyism lie key concerns, says Kate Gordon, the senior planning officer at the Campaign for the Protection of Rural England. The first is the policy's top-down imposition. “It cuts across the planning system and disrupts regional plans that have been put in place democratically over years,” she says. “We support the aspirations of eco-towns, just not how the policy is being carried out. Without co-ordination, the feet will be going one way and the head the other.”

“Of course eco-towns will not be ‘imposed' without local support,” counters Gideon Amos, director of the Town and Country Planning Association, whose former chairman, David Lock, came up with the eco-towns idea. “They'll have to go through normal planning. If they're faulty, they'll fail.”

Dunster understands the concerns, however. “We've had 20 years of poor development on greenfield sites,” he says. There are enough disused airfields, old quarry sites and 'damaged' countryside we can use before we start on the green fields.”

Both Kate Gordon and Richard Rogers propose “retrofitting”: densifying and making green existing towns before building new ones. The problem is that building on brownfield sites is less profitable, while “densification” is as controversial for city dwellers as “concreting the countryside”. The fact is, building ten eco-towns is barely going to dent our housing and carbon problems. We need to improve existing cities and housing urgently and build eco-towns.

It's the poor transport links of many of the proposals that are the biggest headache. For example, plans for Middle Quinton, southwest of Stratford-upon-Avon, Coltishall in Norfolk, Rossington in South Yorkshire and Ford in Sussex all require substantial transport improvements to prevent them becoming isolated or forcing residents into cars to commute to work.

But still the general guiding principle of eco-towns should be embraced. “Instead of asking, 'Why should we build eco-towns?', I'd turn the question round,” Amos says. “Why have we been so blinkered not to build new towns?” The policy, he thinks, is a corrective “against the inherent attitude in Britain that all new development, especially that on greenfield land, is automatically bad. This is our chance to become a flagbearer.”Britain has a good record in building new towns. Bath was once a new town. The beautiful terraces of Edinburgh's New Town were once exactly that, as was the philanthropic housing at Saltaire, New Earswick and Port Sunlight. The 19th-century precursors of the suburb were in London, in Camden Town and Bedford Park, while garden cities such as Letchworth and Welwyn have been influential all over the world. Many were once regarded as blots on the landscape; now they are thought of as stunning examples of town planning.

But, looking at the record of British housebuilders in the past few years, few would be optimistic. Despite exceptions such as the Greenwich Millennium Village, Accordia, a Cambridge housing scheme on the Stirling Prize shortlist, and Dunster's BedZED, our record on new developments is poor. How can the Government make the building industry comply with its new, green regulations?

The Government points to Hammarby Sjöstad, a suburb of Stockholm, as a foreign exemplar. But it was designed 17 years ago when the impacts of climate change were less widely known, so much of the architecture doesn't reach the equivalent of level six of Britain's Code for Sustainable Homes. Dunster thinks that it is “not particularly relevant to Britain's climate and culture. It relies on a whopping great wind turbine or power plant.”

Better, he thinks, to design neighbourhoods that don't demand as much energy in the first place, such as his RuralZED plans. “It's appallingly basic. If you build higher-density, higher-rise neighbourhoods, you need more technology to keep them carbon-neutral because of simple things like less sunlight and warmth reaching the flats. For 70 per cent of the UK, all you need is a simple wood-pellet boiler and solar thermal collectors, not all these wind turbines and photovoltaics.”

Britain already has government-sponsored eco-settlements under way. English Partnerships is creating “eco-villages” on sites from Bristol to Doncaster - all homes built to levels five or six of the sustainable homes code. In 2006, before eco-towns were a glint in Gordon Brown's eye, a new community of 9,500 homes for 24,000 people at Northstowe, outside Cambridge, was announced, an eco-town in all but name, now being considered by South Cambridgeshire District Council. It doesn't conform to the lofty standards of the Eco-towns Prospectus, but with plans for south-facing windows, rainwater harvesting, porous pavements and solar water heating, it gives us a hint as to what to expect. The future is inescapably green.

More information: www.communities.gov.uk

The numbers behind building eco-homes

3 million Number of homes to be built by 2020 under government plans

27% Percentage of UK carbon emissions from housing

20,000 Maximum number of homes in each eco-town

40% Percentage of land in eco-towns to be allocated to green space

£300,000 The average cost of an eco-home, according to a recent report

42 Number of proposed locations that failed to make the shortlist of 15

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