Oettinger said he would decide whether to make the EU's goal of improving energy efficiency by 2020 legally binding to bring it in line with the bloc's other 2020 climate targets.
A first step would be to evaluate progress made by member states towards the voluntary target in 2012, he said.
If member states have made good on their pledges, there would be no need for stronger regulation at European level, Oettinger suggested. But if there is no marked progress in the next ten years, "then we need more and stronger European regulation," he stressed.
Oettinger made the comment at the launch of a joint NGO/industry study arguing that Europe can reduce greenhouse gas emissions by 95% by 2050 by replacing fossil fuels with renewable energy and ramping up energy efficiency.
The study, commissioned by Greenpeace and the European Renewable Energy Council (EREC), says Europe could get 92% of its total energy from renewable sources by 2050 with an aggressive strategy of investing in efficiency technologies and public transport, while shifting freight transport from road and air to rail.
The energy "revolution" will come at a price, though, as the additional electricity costs would amount to €82 billion per year in 2020, while falling steadily after 2030, the study argues. By around 2035, the costs would drop below those of the business-as-usual scenario, said Frauke Thies, energy policy advisor at Greenpeace.
Oettinger welcomed the study as timely input for the Commission's 2050 roadmap, which will set the course of the EU's long-term energy policy. He said he would present the roadmap next spring.
The commissioner said the EU was already making good progress on integrating renewables into the electricity mix. "I would say we'll reach 20% before 2020," he said.
But he added that the EU's objective to improve energy efficiency by 20% by 2020 is more difficult by nature, as it is as yet not perfectly clear what it implies. An informal meeting of EU energy ministers in September would seek to come up with a "clear, precise definition of what 20% higher efficiency means", he announced.
The Commission is set to present its new energy efficiency action plan early next year.