Builder Queries Rating
Mud bricks score poorly
By Dave Crossthwaite
Pictures: Lawrence PINDER
An Eltham builder has called on the State Government to exempt houses made of earth from new energy efficiency laws after its computer modelling software rated corrugated iron a better insulator than mudbrick.
From July this year, all new houses in Victoria must have more energy efficient and water saving features, including a four star rating for building materials. Houses built after July, 2005, will have to meet a rating of five stars.
Earth builder Michael Young put the Governments First Rate program to the test after it awarded one of his mudbrick houses zero stars from a possible five.
Mr Young said further tests using the software, carried out by a Nillumbik Council officer, showed additions such as double glazing and wide eaves made little difference and that bare weatherboard or corrugated iron outperformed solid mudbricks. All three building materials, used alone, scored a zero star rating, but weatherboard and corrugated iron recorded higher energy points than mudbrick.
Mr Young, who trained under renowned builder Alistair Knox, and who like his mentor builds almost exclusively in mudbrick, said the results proved the software was flawed.
"It obviously doesn't recognise the thermal properties of high mass walls and until (it) can, mudbrick should be exempt," Mr Young said. All we're asking for is a stay of execution until they get it right.
But the state's peak energy authority has questioned this.
The Sustainable Energy Authority's leader of building development, David Craven, said the authority had put more than 40 designs through the system with vastly different outcomes.
Mr Craven said mudbrick outperformed weatherboard and corrugated iron in every case.
"There is a whole range of ways you can do a rating," he said.
From Left: A mudbrick house in Swan St, Eltham and builder Michael Young.
"It can come down to the expertise of the operator.
"We'd be happy to review the rating and assist the builder to improve the houses energy rating."
Nillumbik Council's manager of environment and community services Bill Forrest said mudbrick houses in the shire had achieved ratings of up to three stars and no permits would be refused before July.
Mr Forrest said the energy performance of mudbrick had never been tested and there were "significant weaknesses" in the software technology.
"They (The Sustainable Energy Authority) assume mudbrick performs the same as a stone wall. They are guessing and they are getting it wrong." Mr Forrest said. "Failure of mudbrick houses to comply with First Rate should not be the basis of refusing permits." Mr Craven said the CSIRO released test results for earth materials in 2000.
"We're confident in the Software and the 30 years of international research it is based on," he said. "Discussions have been held with the industry and the Government is committed to working with it before and after July."