US President Barack Obama on Monday signed an executive order to demand federal agencies to improve their environmental, energy and economic performances.

The order requires federal agencies to set a 2020 greenhouse gas emissions reduction target within 90 days, increase energy efficiency, reduce fleet petroleum consumption, conserve water, reduce waste, support sustainable communities, and leverage federal purchasing power to promote environmentally-responsible products and technologies.

"As the largest consumer of energy in the US economy, the Federal government can and should lead by example when it comes to creating innovative ways to reduce greenhouse gas emissions, increase energy efficiency, conserve water, reduce waste, and use environmentally-responsible products and technologies," said Obama in a statement.

"This executive order builds on the momentum of the Recovery Act to help create a clean energy economy and demonstrates the Federal government's commitment, over and above what is already being done, to reducing emissions and saving money," the president said.

The US Federal government occupies nearly 500,000 buildings, operates more than 600,000 vehicles, employs more than 1.8 million civilians, and purchases more than 500 billion dollars per year in goods and services.

The new order requires agencies to measure, manage, and reduce greenhouse gas emissions toward agency-defined targets.

It also requires agencies to meet a number of energy, water, and waste reduction targets, including 30 percent reduction in vehicle fleet petroleum use by 2020, 26 percent improvement in water efficiency by 2020, 50 percent recycling and waste diversion by 2015, 95 percent of all applicable contracts will meet sustainability requirements.