The green lobby wants low energy, sustainable, recyclable ecohomes:

How would you feel if the government banned the production of luxury cars? Those sleek, sensual dream machines you aspire to guzzle far too much gas and take up too much parking space. Instead, you'll have to buy your precious motor second-hand, or make do with a Mini or a fuel-efficient diesel Volvo.

Carmakers and buyers are not faced with that scenario yet, but its equivalent is happening in housebuilding. The industry is under pressure to make the homes it builds more energy efficient, less environmentally damaging and altogether more sustainable. And the prospect of massive housebuilding programmes in the government's South-eastern growth areas of the Thames Gateway, Milton Keynes, Ashford and Stansted has raised the stakes for environment lobby groups. As a result they are trying to ensure that housebuilders build only green homes on brownfield sites.

The World Wildlife Fund UK is pressing for the new communities to be developed to a minimum standard of "very good" under BRE's EcoHomes measurement system, which ranks homes on a four-stage scale: pass, good, very good and excellent. To add weight to its case, the organisation this summer published One Planet: Living in the Thames Gateway, an in-depth report by BioRegional Development Group on the implications of imposing more rigorous environmental standards on the 200,000 homes to be built in the Gateway.

The green agenda is becoming more complex. Housebuilding is having to innovate and move into new areas quickly

WWF UK's strategy, part of a campaign called One Million Sustainable Homes, has impressed deputy prime minister John Prescott: he has given the WWF representation on an industry advisory group convened to review of Part L of the Building Regulations and has pledged to come up with environmental targets for housing in the growth areas. These targets could be announced later this month at the government's Better Buildings summit.

"We've made inroads," says Paul King, director of WWF's One Million Sustainable Homes campaign. "We're pretty positive." To maintain the pressure on the industry, WWF is also working with Insight Investment, the asset manager of banking group HBOS, on an investigation into the environmental credentials of the top 13 listed housebuilders, to be published in December. "We've done this because housebuilders told us that one of the barriers to sustainability was the perception that investors are not interested in it," says King. "We knew that was changing. Housebuilders are going to be getting pressures from investors and customers."

Other environmental groups support the WWF's stance. "We've already got tried-and-tested best practice standards in place, so why aren't they set for developers building in the housing growth areas?" asks Zoltan Zavody, policy analyst at the Energy Saving Trust. "In the priority areas housing will be at high density, where it is a lot easier to achieve best practice, and most of the environmental improvements are not that difficult to do – we're talking about better insulation and central heating systems."

But those on the receiving end of environmentalists' pressure do not quite see it that way. They fear expectations may run ahead of what the market will accept and what makers of environmental technology can realistically and cost-effectively provide. "There is a need to sell the environmental consequences to the market," says Clive Wilding, managing director of Raven Residential. "The industry will always respond to the market. We need to think about things like tax concessions on the rates for energy efficient homes, which happens in Germany. If you don't let the market drive it, you'll meet resistance."

John Cover, technical director at Taylor Woodrow, agrees: "Agents' and valuers' approach to property doesn't take on board the environmental agenda," he says. "They'll talk about the benefit of conservatories and swimming pools, but I've never seen anything from them that suggests that environmental features add value."

WWF's report on the Thames Gateway shows that it does cost more to build homes with higher environmental standards, but argues its case on the premise that housebuilders will be able to recoup the extra cost in planning gain and higher selling prices. According to Cover, government landholders are already making the former concession: "English Partnerships recognises that there's a cost to it and knows that the money has to come from somewhere so it discounts it against land values."

But making buyers pay more for a green home is a more difficult question. "We don't factor in a premium on the sale," says Cover. "It is a cost." Cover says an immediate solution would be for green technology to be made available as an optional extra, at a cost. "People don't have experience of green homes," he points out. "We think there should be a way to offer it to customers so that those who see a benefit can have it. We're looking at making environmental packages available with everything from water butts to renewable energy technologies."

However, even this is not as straightforward as it sounds, cautions Richard Hodkinson, director of innovation consultant Richard Hodkinson Consultancy. "We have to be realistic and careful about what people will pay for. We need to be sure that things are doable." The jury is out on some forms of environmental technology, such as greywater recycling – systems that recycle washing water for toilet flushing. "We recommend that our clients don't get involved in greywater recycling because of the maintenance, management and capital cost issues," says Hodkinson.