Labor has given, under its latest climate change election promise, $1 billion in tax breaks on investments in energy-efficiency measures for commercial building.

But only hours after announcing the proposed tax break, the Gillard government said it had made another cut to an already existing climate change program to pay for campaign promises. This time, it was $41 million from the Howard-era Low Emissions Technology Demonstration Fund.

In a third day of climate change declarations to remedy a deficiency caused by postponing the emissions trading scheme until 2013, Prime Minister Julia Gillard said businesses would be entitled to a 50 per cent tax break for investments in energy-saving measures for supermarkets, hotels and office blocks.

Set to run from mid-2011 to mid-2015, the green building tax break will cost $180 million by 2012-13, and $1 billion by 2018-19, mainly in lost tax earnings.

Labor, in the short term, will top up the current Green Building Fund with an additional $30 million to pay for energy-saving measures in buildings prior to the tax break implementation.

Commercial buildings account for 10 per cent of the country's greenhouse gas emissions. The policy won Labor some much-needed support after it was slammed last week for its climate change measures.

There were some smart ideas in the tax proposal, although it should be part of a larger package, according to the Energy Efficiency Council chief executive Rob Murray-Leach.

Meanwhile, the Australian Conservation Foundation said the policy is ''important''.

The commercial building sector could slash 80 megatonnes of its carbon emissions by 2020, and the tax break was a significant step towards reaching those savings, according to Property Council of Australia chief executive Peter Verwer.

Labor will provide for the first $180 million of the green building tax break from the $652.2 million renewable energy and energy efficiency fund it formed in the May budget.