Stefan Scheuer, managing director of the SPRL environmental consultancy and former policy director at the European Environmental Bureau, predicted that the plan would fail "for the simple reason that it does not set itself specific sectoral or member state-relevant targets".
"The plan is far too timid to reassure us that it can achieve the 20% target," he told EurActiv.
The Commission's low carbon roadmap for 2050, which was also launched yesterday, says that emissions reductions of 25% can be reached by 2020 – a much-needed 5% increase on the EU's official target – but only if the energy savings goal are met.
"We need to start the transition towards a competitive low-carbon economy now," Climate Action Commissioner Connie Hedegaard stressed yesterday. "The longer we wait, the higher the cost will be."
But Randall Bowie, an energy consultant who in 2006 was the desk officer responsible for designing the Commission's Energy Efficiency Action Plan and Energy Services Directive, forecast that the goal would not be met by the efficiency plan on the table.
"If you have [binding] targets it ensures that the member states will do a good and ambitious job of implementation and transposition," he said, speaking over the phone.
Without obligations on implementation and verification, "you're less likely to meet the target," he added.
Luigi Meli, director-general of the European Committee of Domestic Equipment Manufacturers (CECED), agreed.
"Waiting until 2013 to make a further assessment on whether Europe is behind target is totally unjustified," he told EurActiv.
"There are some good intentions in the plan but not the sense of urgency that is required to redress the situation now."
In January, Commission President José Manuel Barroso called for "concrete steps" to meet the EU's target.
Many expected firm legal targets to be announced this year. But the document only proposes to review whether these are necessary at the end of 2013.
By then, time will be "getting fairly short," Bowie said, "and you'll have to start speaking in terms of longer-range targets with intermediate targets in between".
Yet EU diplomats claim a "firm conviction" that the proposed measures will be effective. The plan's leading principle "is to propose stringent binding measures without binding national targets," the document says.
Around 40% of the current energy efficiency gap should be covered by a national energy saving obligation scheme that will yield savings of up to 100 million tonnes of oil a year by 2020, diplomats say.
Another 30% will come from the roll out of legislation to ensure performance-based energy contracting and the rest from measures such as a requirement for public authorities to refurbish at least 3% of their buildings each year.
New legislation is also promised on eco-design labelling for windows, and 'split incentive' situations in which tenants and landlords are reluctant to pay for energy savings.
But in the absence of national sectoral targets to weigh the progress of these measures, Scheuer said it was "wishful thinking" to imagine they would bring the desired outcome.
Randall Bowie was particularly concerned that the 3% target for building renovations only applied to the public sector – 12% of Europe's building stock – and, even there, lacked detail.
"Utilities have to be given very clear long term requirements and not go in and do the very quick, cherry picking-type of shallow renovations," he said.
"There's a need for the member states to be required to develop long-term building renovation targets. You have to address the private sector more carefully and they haven't done that. By leaving it out they make it more difficult to reach the 2050 objective."