The World Wildlife Fund (WWF) has praised the government's £1 billion energy plans but is calling on the authorities to do more in the long term.
Zoe Leader, sustainable homes policy officer at WWF-UK, said the failings of Britain's existing housing stock needed to be addressed.
She explained that the charity believes the government should "put in place a clear long-term strategy for making all homes achieve their energy efficiency potential" because "for many UK homes, insulation alone will not be the answer".
The WWF is advising people to turn to solar water heating, solid wall insulation and zero-carbon technologies to help the country meet its energy-efficiency targets.
Under the government's Home Energy Saving Programme, pensioners will benefit from free insulation, with the aim of every household being made more energy-efficient by 2020.
The poorest families will also receive a freeze on this year's energy bills and pensioners and the unemployed with young children will receive an extra £16.50 each week in a severe winter.
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