* PM wants UK to be most energy-efficient country in Europe
* Various existing green policies have been criticised
LONDON, Feb 4 (Reuters) - Britain needs a single coherent strategy to become the most energy-efficient country in Europe, Prime Minister David Cameron said in one of his strongest speeches on the value of a low-carbon economy on Monday.
Cameron spoke at the launch of a new programme to accelerate the deployment of energy-saving measures and get the most out of the many existing government policies to improve energy use.
Since taking over in 2010, the coalition government has introduced a range of policies to help spur clean energy investment, boost efficiency and help British people and businesses lower their energy bills, some of which have been criticised for overlapping or falling short.
The Prime Minister said on Monday he wanted "one coherent strategy" to make Britain energy efficient.
"In the global race, the economies in Europe which will prosper are those which are the most energy efficient," Cameron said.
"We can't afford not to prioritise green growth right now."
Manufacturers' trade body EEF said the government needed to provide a supporting framework for industry.
"The current policy approach is not delivering the desired results. There are signs that the UK is faltering, losing out to China, the United States and other economies that are experiencing rapid growth in this sector," said Gareth Stace, EEF's head of climate and environment policy.
British energy consumption is forecast to rise by a third over the next 20 years, adding to greenhouse gas emissions and burdening the economy if nothing is done to control energy use.
The government has said Britain could save 196 terrawatt hours in 2020, equivalent to 22 power stations, through investment in energy efficiency, which would also reduce carbon emissions by 41 million tonnes.
With the global low-carbon energy sector set to grow to a value of $4 trillion by 2015, the government also sees opportunities for job growth and boosting the economy.
Research by the Confederation of British Industry last year showed the right low-carbon policies could add 20 billion pounds($31.5 billion) to Britain's GDP by 2015.
One of the government's newest policies is the so-called Green Deal, which started last month and permits loans to homeowners to help them pay for efficiency measures such as loft insulation, modern boilers, draught proofing and other materials.
The scheme has been criticised, however, for high interest rates underpinning it, the slow uptake of loans and fears that it will increase fuel poverty.
The Prime Minister conceded the scheme had made a "modest start" and said it would take time to build.
"This deal will cut carbon, cut bills and put people back in work," he said.