Saying he wants to lead by example on global warming, President Barack Obama has directed the federal government to reduce its emissions of heat-trapping gases by 28 percent in the next decade - a goal that exceeds targets for the US as a whole.
As the single largest energy consumer in the US economy, Obama says the government spent more than $US24.5 billion ($NZ33.2 billion) on electricity and fuel in 2008.
He says achieving the new pollution goal would cut federal energy use by the equivalent of 205 million barrels of oil, the same as taking 17 million cars off the road for one year.
Obama's announcement comes a day after the United States pledged to address global warming by cutting the nation's emissions of greenhouse gases by 17 percent by 2020.
The commitment to the UN climate body must get approval from Congress, which is not guaranteed.
The initiative on federal agencies follows an executive order Obama issued last October and requires agencies to set targets for reducing climate-altering pollution from buildings and fleets.
The initiative does not apply to the emissions of companies that supply the federal government or those from federal employees' commutes.
Obama said the initiative would lower costs, reduce pollution and shift federal energy expenses away from oil and toward renewable energy.
The order leaves it up to individual agencies to set targets, with an overall goal of 28 percent reduction for the federal government from 2008 levels.
The US goal submitted to the UN is based on 2005 emissions. Emissions caused by use of electricity and fuel were higher in 2008 than in 2005, making exact comparisons difficult.
The Defence Department pledged Friday to reduce greenhouse gas emissions in noncombat areas 34 percent by 2020, but did not include combat operations, which account for about 62 percent of the department's carbon footprint.
Frances Beinecke, president of the Natural Resources Defence Council, called the 28 percent goal "a bold target" that showed "real leadership in the fight against global warming."
The mandate comes as the Obama administration takes steps to require automakers and large industrial facilities to cut greenhouse gas emissions. The president wants Congress to pass a bill setting mandatory limits.
