"Their advice was 'find somewhere else'," Tisdale said.

"The reason it was so cheap was that it was full of rubbish. They said I'd be crazy to buy it."

Fortunately, Tisdale knew something they did not.

"There's a permanent spring that runs through this property. That's why [Major George Nicholas] Weston built the original house here in the 1830s, because of the water. Back then the spring used to trickle down through this paddock. So they dug out a hole here and made it into a dam."

Over the years the 800-hectare Horsley estate - which had originally been granted in 1804 to Weston's father-in-law, Colonel George Johnson, by Governor King for his part in quashing the rebellion of Irish convicts at Vinegar Hill - was subdivided. The dam became an unofficial rubbish tip, gradually filled in with decades worth of unwanted building materials. Underneath, the once pristine spring waters still ran, polluted and forgotten.

Tisdale went ahead and bought the site for a bargain $600,000 a year ago. Now the businessman-turned-environmental campaigner is halfway towards realising his dream: turning the rubbish dump into an eco research park, dedicated to sustainable housing, with fully functioning, state of the art houses completely independent of the mains water, electricity or sewer systems.

Already phase one of the project, the landscaping, is complete. Bulldozers have removed tonnes of discarded bricks and other building rubble from the site. The original water courses have been restored, allowing natural spring water to fill the newly created ornamental lake. Twelve thousand tonnes of sandstone have been imported to echo the block's colonial heritage. And about 3000 native trees and shrubs have been planted, recreating the kind of flora that might have existed before white man arrived on the shores.

As Tisdale gave the Herald a guided tour of the transformed garbage tip it was clear he was proud of what has been achieved, but his focus is on the vision ahead: submitting the next stage of his grand design to Fairfield City Council.

On either side of the newly created lake, Tisdale intends to build two prototype prefabricated display homes, each aimed at a different end of the housing market.

The first, designed by the Australian architect James Gardiner, is pitched at the affluent, environmentally conscious domestic consumer. For about $600,000 they would be able to erect a three-bedroom home, complete with grand lobby, library, dining room and a prefabricated lap pool.

What makes it so affordable is that each factory built module is based on the dimensions of a shipping container, meaning it can be easily transported, piece by piece, on conventional container trucks, then assembled at the site.

The other prototype, designed by a Norwegian expert, Johan Naess, is pitched at the Third World market, desperate for safe housing at affordable prices.

"Basically, it's a kit home that you bolt together yourself like a Meccano set," Tisdale says. "It has been designed for sale in Third World countries, but it meets Australian building standards. It uses high-speed engineering production techniques to lower building costs dramatically. The assembly is like an Ikea house: you need an Allen key to put it together at the weekend."

Tisdale, 51, trained as a fitter and machinist before starting his own company in 1988. Today TM OverExposure specialises in high-end engineering. "We did the concept design and the prototype for the Olympic cauldron which Cathy Freeman lit in 2000," he says. At his sprawling factory in Smithfield, a team of 30 beaver away building a wide range of commissions, everything from urban street furniture and metal sculpture to train cabs.

Part of his wealth, ironically, comes from supplying components for the huge trains that carry coal and other minerals from to mines to ports - ultimately contributing to global warming. It is a responsibility Tisdale readily admits. He has now pledged that 1 per cent of his company's gross annual turnover will be handed over to Greening Australia.

What made him become "a greenie", he says, was his battle to clean up his local park in Greystanes. Benaud Street Park, named after the cricketer Richie Benaud, had become plagued with late-night drinking, drug-taking, muggings and vandalism. Locals called it "Chunder Hill", he recalls. "Deros used to go there to get stoned and drunk because you get a great view of the Sydney Harbour Bridge and the city lights from up there."

In 2003 Tisdale led a campaign to make the park beautiful again. Thousands of trees were planted, safety lighting installed and rubbish removed. It took three years, but eventually the park became safe again for the public.

By that time Tisdale was an environmental evangelist - becoming, he believes, the first chief executive in Sydney to make all the cars in his company fleet hybrid models.

Yet as a successful businessman Tisdale knows there is money to be made out of green engineering - particularly prefabricated housing. Architects such as Frank Lloyd Wright advocated prefabrication before World War I, but the production costs were always prohibitive. Now modern engineering makes prefab housing much cheaper than conventional alternatives.

"The aim is to build high-speed, low-cost housing for volumes of people," Tisdale says. They will be made in China ("Sadly, it's too expensive to manufacture here in Australia"), at the rate of up to 200,000 kit homes a month.

And although the concept is aimed at African and Asian countries, Tisdale says "there's no reason they shouldn't be used in Australia. They'll look just like a normal house."

Other green companies will be invited to showcase their products at the Horsley property, to prove that even in urban Sydney a home can be fully sustainable, completely independent of the usual power and water suppliers. For example, wind turbines are being installed to provide the electricity, while the effluent will be treated by a waste management system imported from Russia.

"Our main aim is to work with Fairfield City Council to set up an R & D park where we can test environmentally friendly systems over time," Tisdale says. "It will change over the years."

http://www.overexposure.com.au