Dr Williamson has relied on the official government figures and studies from the Environment Department and the former Australian Greenhouse Office into household energy use and household emissions.
He concludes that the benefits – as currently claimed – are bogus.
Two other experts who provide advice to federal government departments on greenhouse gas emissions told The Australian yesterday Dr Williamson’s analysis was correct.
The emissions reduction claims did not withstand serious scrutiny, they added.
“The numbers claimed are absurd — they are complete crap when you do the calculations,” one eminent expert said.
Dr Williamson challenged the Department of Climate Change to prove its claims by releasing its modelling calculations.
“The benefits have been exaggerated by a considerable factor, and none of the government’s numbers stack up,” said Dr Williamson.
The average household’s energy use is responsible for about eight tonnes of greenhouse gas emissions a year.
Dr Williamson said the most optimistic scenario could see the emission reduction get to 0.4 tonnes per household, which meant that the total carbon reduction by 2020 would be about 10 million tonnes.
This would mean that the scheme had cost taxpayers more than $200 a tonne.
A Department of Climate Change spokesman said the estimated abatement of 1.65 tonnes of carbon per installation per household year “takes into account average energy use by households as well as the split of electricity and gas use.
“It is also averaged over Australian climate regions.”