We're now used to seeing white goods that are energy rated. But what if you could buy a house with one to five stars?

Well you can. In fact a federal government plan may soon make energy ratings for houses compulsory.

Which way windows face, what sort of materials are used and how much insulation is used, can all make a difference to not only how comfortable your house is, but how much energy you save.

In a move to save energy and the environment, the government decided to bring in a rating scheme and turned to CSIRO to help devise a computer software program.

CSIRO developed a program called Nathers, or Nationwide House Energy Rating Scheme.

The proposed building's size, orientation and construction materials used are entered into the program.

This building description with the post code of the building site, to determine climate, is used to work out a zero to five star rating.

A low rating means either high energy bills or an uncomfortable house. A four or five star design means a thermally comfortable house, that minimizes the need for heating and cooling.

"The difference between a 5 star building and a zero star building is very large indeed and savings of 20 to 40 percent in heating energy should be possible."

The rating system is already compulsory in Canberra and will be brought into New South Wales at the end of 1999.

Some councils like the Camden City Council in Sydney already require that new houses built in that area are rated by the program.

"In future versions of the software, we hope to produce a version which will actually provide some advice about where the most likely improvements are available."

If the house energy rating scheme is enforced throughout Australia, using the Nathers software, it will mean more comfortable houses, a saving on energy bills and a cleaner environment