"But this is very difficult to evaluate, and so we must work out many details before it can be applied," Borloo told DPA news agency.
The proposal was made on the third, and last, day of an informal meeting of EU environment and energy ministers in Paris devoted to drafting a package of laws that would reduce greenhouse gas emissions, increase the use of renewable energy sources and make energy use more efficient across Europe.
France, which assumed the rotating EU presidency on July 1, and Brussels want to have the package approved by the European Parliament by the end of the French term, on December 31, or at the latest in March 2009, just ahead of European Parliament elections.
Feran Tarradelles Espuny, the spokesman for European Energy Commissioner Andris Pibalgs, said that ministers were considering making energy efficiency goals as legally binding as budget deficit ceilings are.
This could be a global directive constraining EU member states to reduce energy consumption by 20 percent by the year 2020 or measures directed at specific energy-intensive sectors, he said.
German Junior Finance Minister Jochen Homann said Germany "would have no problem with (such a directive) on a European level."
In addition, Tarradelles Espuny said, measures were being considered to set minimum efficiency standards for a wide range of equipment, such as light bulbs, electronic standby devices and street and office lighting equipment.
In one year, standby devices across Europe consume as much energy as does the country of Hungary, he said, and noted that a vote would be taken on Monday on the standby device proposal.
On Friday, Pibalgs said a reduction of 20 percent in the EU's energy consumption would represent annual savings of 100 billion euros ($160 billion), at an oil price of 60 dollars per barrel. And it would reduce carbon dioxide emissions by 780 million tons.
Energy efficiency "is our best tool to mitigate the effect of increasing oil prices on citizens' welfare, improve the EU's competitiveness and achieve our goals for security of supply," Pibalgs said.
In addition, Borloo said EU members were strongly in favour of the goal of having renewable energy sources represent 20 percent of all energy use by 2020, with a minimum of 10 percent in transport, whether it be biofuels or electric automobiles.
EU environment ministers were also looking to increase the share of carbon dioxide savings in the production of some biofuels by 35 percent in the near term, and by 50 percent by the year 2015, Borloo said.
A double game with Russia
Earlier on Saturday, the former head of the International Energy Agency (IEA), Claude Mandil, told participants at the meeting that Europe was playing an ineffectual double game with Russia and must cease if it wants to better diversify its energy sources.
"On the one hand we are horrified that there will be a shortage of Russian gas and, on the other hand, we are verbally aggressive with Russia," Mandil said.
"Let's be flexible," he went on. "Let's stop provoking Russian sovereignty in the belief that we can dictate Russian behaviour on energy."
Borloo closed the three-day meeting by saying it had been "indispensable" and "absolutely crucial."
"Big objective difficulties remain to be overcome, but the desire to succeed is also big," he said.