Renewable energy use in the nine ACT government directorates plunged by 83 per cent in 2012-13, from more than 20 million kw/h in 2011-12 to less than 4 million kw/h in the past year according to their annual reports.

Carbon emissions from the ACT public service rose 15 per cent over the past year, partly as a result of the cuts in green energy, almost topping 100,000 tonnes in 12 months

A spokesperson for Environment Minister Simon Corbell said this was due to the government suspending its 37.5 target for green energy use in ACT directorates, quietly dropping it to five per cent in 2012.

In the 2011-12 budget, the ACT government wrote that it would be leading the way on greenhouse gas emissions by increasing its purchasing of green energy in government departments, up from 32.5 per cent in 2010-11.

"Continuing with its promotion of renewable energy use in the community, in 2012-13 the government will lead by example with 37.5 per cent of total Government electricity use coming from renewable sources," they wrote.

In addition, only just over half of all ACT directorate used more than five per cent of renewable energy in 2012-13, with Capital Works, Education and Training and Justice using next to zero per cent.

Minister Corbell's spokesman said the government had decided to re-allocate the funding from renewable energy purchases to maximising energy efficiency opportunities in government buildings and operations.

He also said the decision to reduce green power funding in 2012 had been only temporary.

"The GreenPower funding has been re-directed to the government’s Carbon Neutral Loan Fund to fund energy efficiency projects across the ACT government," he said.

"The funding has also enabled the employment of two energy project officers, with specialist knowledge in energy efficiency opportunities, to identify and implement energy savings projects across the government."

The spokesman said that, while there had been an increase in carbon emissions due to the government's decision, purchasing renewable energy had been only a temporary fix while improving energy efficiency would provide long lasting benefits.

"Energy efficiency projects will have a real and positive effect on the government’s emissions profile. The government is of the opinion that this change of focus from purchasing offsets to energy efficiency savings represents better value for money from the allocated funding," he said.

Conservation Council ACT executive director Clare Henderson said while she supported the ACT government's efforts to address climate change, she was disappointed to see an increase in greenhouse gas emissions.

"We hope that this is temporary and that various energy efficiency measures being put in place will address this in the near future. It may be better to reduce expensive GreenPower purchases with local energy efficiency measures. However whatever option is used we do want to see actual reductions," she said.

Ms Henderson said she would like to see greater and faster reporting on the ACT's progress towards reducing greenhouse gas emissions.

Climate Council chief commissioner Tim Flannery said it was a sensible move to focus on increasing energy efficiency before switching to a renewable energy source.

"I think energy efficiency is the first, obvious stop," he said. "Absolutely. It's so much cheaper, by and large, than buying new infrastructure. It should always be the first step to make the most of the energy you have on hand."

But Mr Flannery said, depending on the source of an organisation's electricity, there was no reason why energy efficiency measures and green power couldn't be put in place at the same time.

"Depending on where you are, and what your situation is, you can do both simultaneously. Just say you’ve got a huge dependency on fossil fuels, you’d want to pursue energy efficiency and a push towards renewable energy," he said.

"You don’t necessarily have to one without the other one."