No longer was volume housing just a question of land banking, pattern books and a glamorous show home: house-builders were saving the planet.

It’s now 2008, and the sound of credit being crunched is drowning out the rallying cries. Amid declining residential values, the profit margins that last year could accommodate triple glazing and a measure of idealism are coming under pressure. For housebuilders the decision might prove to be code level two, or cold hard cash?

The 10 proposed eco-towns will almost inevitably be affected. Before bidding on these sites, consortiums will look at what the major mortgage banks will lend on completed properties 18 months down the line. In a declining market, it becomes harder to be sure of a valuation that would allow developers to recoup the extra per unit cost of the integrated CHP plant or solar farm.

For the past 15 years, the supply side of the housing industry has had its own way. It’s hard not to make a profit when values rise seemingly of their own accord, the pension-poor classes are buying to let, and local authorities have limited control over what gets built — so city flats are in oversupply and family homes in undersupply.

With the government also heavily reliant on housebuilding as a motor for the economy, ministers seem to have forgotten the days when they directed housing policy. But even if the housing market is having a moment rather than a meltdown, the possibility that policies as important as eco-towns and zero carbon could be compromised by the vagaries of the market should be enough to convince Caroline Flint that it’s time to grasp a few more levers of power.