Green's Spring conference targets the banks and Labour

The Green Party is holding its Spring Conference in Nottingham this weekend. But its choice of location is no coincidence.

The campus venue at Nottingham University is home to some of the latest research in creating eco-friendly homes.

This political party's come a long way since it was formed at the Bridge pub at Napton, in Warwickshire, 40 years ago. Inspired by the growth of the green movement in Germany, the party went through early birth name change: People, then Ecology before settling on the Green Party.

Its leader is former Guardian journalist Natalie Bennett. Elected last autumn, her priority now is to spread the message that the Greens aren't a single issue political party.

The banks are in her sights for causing the global recession. The multinationals for not paying "a fair" tax. So is the Labour Party for taking Britain into the Iraq war.

"Because Labour is staying so close to the Tories on policy terms, we have a huge opportunity to talk about our policies, " she told me.

"Making the minimum wage a living wage, for example. We are wanting to renationalise the railways. That's popular with every audience I ever come across."

The Greens have two MEPs and in Caroline Lucus, a Westminster MP.

"Caroline has before Parliament a land value tax bill, " added Natalie Bennett.

"This would replace council tax and business rates with a far more equitable system.

"It would stop land banking and would ensure that local councils have the funding they need."

One of the party's councillors is Richard Mallender from Rushcliffe in Nottinghamshire.

Before the conference started, he was shown some of the world-leading research at Nottingham University on creating energy efficient homes.

In a quiet cul-de-sac on the university campus, there are six experimental carbon-zero houses . They will shape future home design and help meet the 2016 deadline for Britain's carbon reduction targets.

"We developed these carbon zero homes from the design and development stage through to people living in them," said Professor Mark Gillott, of the University's School of Architecture and Built Environment.

"We feed that back to industry so when we get to 2016 and we build these homes on mass, we'll have learnt the lessons to smooth the way."

Mr Mallender is one of the Greens' 134 councillors in England and Wales. He believes local councils have a key role in delivering those targets.

"This is the standard of housing we need to see for the whole of the UK," he told me.

"It's also about getting building regulations up to standard and the building industry working smarter with local councils."

The Greens believe they are no longer a fringe party. Their message and policies from the Nottingham conference could set the tone for the party's next 40 years.