So, finally, reluctantly, George Osborne, who has become a byword for U-turns and reversing plans made on the backs of envelopes, has decided to boost spending on housing projects in order to create jobs and provide a financial stimulus to someone other than his millionaire mates. The need for the Government to invest in, or at the very least stop slashing, essential public services has been glaringly obvious for a very long time. Even the IMF, not usually known as a fan of government spending, has been saying increasingly loudly that austerity has to stop. So we probably won't see a U-turn this time, but we should.

Here we have a range of measures that bear the half-baked stamp we have come to expect from the Chancellor. He's going to do something to tackle the housing shortage. But that something is to allow developers to hack into invaluable green-belt land, to drop rules demanding that social housing be built alongside the private, and to put government guarantees behind new homeowners – likely to be mostly first homeowners – who are going to be taking on huge debts. As though additional private debt (and since new homes usually drop in value once the first coat of paint is dry, quite risky debt) is just what the country needs.

What is most likely to be created is identikit suburban enclaves of expensive detached homes, predominantly in the south-east of England. These enclaves are likely to be car-dependent, and at the outer limits of energy-use regulations if David Cameron's choice of new planning minister Nick Boles – an appointment that isn't so much a fox put in charge of the henhouse as a fox thrown into the middle of the run and told to tuck in – is a guide.

Not content with squeezing down wages as fast as possible in the Chinese direction, Cameron wants to model our planning rules on those of China. And as anyone who's ever visited Beijing will tell you, that's worked out really well if you like endless traffic jams, concrete jungles and gross over-development.

If you want, however, to protect the farmland that we need to grow food for our own consumption in a world market that's increasingly volatile, building new homes on the green belt is not the way to go. If you want to protect the green spaces that we increasingly know are a significant contributor to human health and wellbeing, not to mention the biodiversity of our much abused countryside, then go elsewhere.

Dealing with the housing crisis is urgent: far too many people are sofa-surfing, far too many families are overcrowded. And the homeless numbers are growing. But we should be using brownfield land, sensitive suburban extension and infill, refurbishing existing buildings and thinking creatively about how we can ensure people are living in homes the size they want. If their houses are too big, can we build or refurbish appropriately sized homes that are local, attractive, well-serviced, desirable?

A sustainable approach would revive, support and boost housing co-ops and community land trusts – legal structures that ensure homes remain in social use in perpetuity and that the people who live in them retain control over their lives and the chance to contribute to their community.

The Government announcement only provides for 15,000 homes – a tiny fraction of what we need, but the sum they are contributing is getting developers off the hook. The Green party's fully costed 2010 general election manifesto allowed for £4bn to be spent in 2011 alone on building council and other social housing – seriously tackling our current critical shortage.

And then there's the critical issue of regional policy. While in some areas of the UK, homes to rent are snapped up with desperate speed, in other parts of the UK economic decline has left large numbers of solid, potentially comfortable homes empty, the value of the asset usually declining fast. We urgently need to rebalance the UK economy, creating jobs in the North, the Midlands and Wales through investment and policies that encourage the development of co-ops and community enterprises – such as renewable energy generation, encouraging the return of farming and craft, and rebuilding local economies towards greater self-sufficiency to prepare for a low-carbon world.

Ultimately, there are bigger, broader issues to address than funding. The Government should be introducing a land-value tax and greatly improved conditions for tenants of private landlords, who shouldn't be vulnerable to being thrown out on a whim.

Eventually, we need, through these and other measures, to get back to the point where a flat or house is truly a home, not primarily an "investment", a prohibitively expensive gamble, or a hopeless dream.

Yesterday's moves don't bring us one single step closer to that, but there's no reason why we shouldn't think seriously about how that could happen, with a Government focused on human wellbeing not corporate profits, and prepared to take steps to plan sensibly for the future. We are now creating structures that should be in place for the next century and more – as so much of our existing housing has been. Once it is there, it stays. Let's get it in the right place.

Natalie Bennett is the leader of the Green Party