Aside from the lack of lawn, the house appears little different to the other homes in the street.

But while his neighbours fork out about $1600 annually on gas and electricity, Mr Reefman will pay nothing.

He will actually pocket $800 from his small solar power system.

Mr Reefman, a Portland builder and convener of the Portland Sustainability Group, recently moved his family into a new 8.1 star house that he designed and built.

The system goes up to 10 and Australia is moving towards a six-star requirement for new homes in the next few years.

The average Australian home is about two or three stars.

Since moving in during September, the Reefman family had used slightly more energy than produced by its 1.4kW solar system.

Last week the house went zero carbon, by producing more energy than the family used.

This was because of a huge number of efficiency measures built into the house and also the low-energy needs of every domestic appliance.

The biggest factor is the way the house is oriented on the block, taking full advantage of the sun. The house is heavily insulated, internally and externally, and has a strong emphasis on northerly windows.

It also has a cooling tower that takes out unwanted heat during summer.

Even if the Reefman home did not use solar power, the heating and cooling costs were predicted to be between $10 and $20 a year.

Although they moved in just after winter, the family found it only needed to heat the home every three or four nights. Each night the heating costs between 15 and 20 cents.

The house has all manner of energy efficient features, including green switches that kill the phantom energy of microwaves and stereo systems, an exceptionally efficient fridge and specially-chosen blinds that keep the heat from escaping during winter.

Mr Reefman estimated that with all of the efficiency measures his family's home cost $40,000 more than the average new house.

Based on the power bill savings, he said a family could gain that investment back in 16 years.

But he pointed out that the housing obesity seen in Australia over recent decades - where houses have grown from an average of 18 square metres to 30 - costs each new home owner about $70,000 more.

THE AGE