Almost 95% of families struggling to pay their energy bills will still be in fuel poverty in 2030, analysis shows.
Ministers have been accused of "throwing in the towel" on tackling fuel poverty.
Research shows just 6% of fuel poor households will be out of that category by the end of the decade.
Greenpeace UK is threatening legal action over the Government's failure to meet requirements to reduce fuel poverty.
The charity said ministers are using outdated fuel poverty data from 2020 in its strategy.
The Government said energy efficiency policies would reduce the number of households that were in fuel poverty in 2020 by 12% by 2030.
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However, the number of fuel poor households in the UK - now an estimated 6.7 million - has more than doubled since then due to wholesale energy price rises over the last year.
Greenpeace calculated that this means the number of households in fuel poverty will only reduce by 5.8% by 2030.
Under the Warm Homes and Energy Conservation Act 2000, the government is obliged to upgrade as many homes “as is reasonably practicable” of people living in fuel poverty by the end of 2030.
Greenpeace’s lawyers believe it is “potentially unlawful” the Government is failing in this “legal duty”.
The charity is threatening to take the Government to court unless it immediately carries out a review into its strategy for tackling fuel poverty and demonstrates how the target could be hit.
Greenpeace’s head of UK climate Mel Evans said: “By throwing in the towel on tackling fuel poverty the government has shackled the poorest people to the coldest homes and the highest bills.
“Almost a quarter of all households are now in fuel poverty. This is a national crisis yet the government’s failing strategy for tackling it means that at this rate it won’t meet its legally binding 2030 target until close to the end of the next century.
“A national home insulation programme can lift people out of fuel poverty, support better health and tackle the climate emergency. Unless the government gets on with it, we'll see them in court.”
A Government spokeswoman said: “The fuel poverty target for England is to ensure that as many fuel poor homes as possible achieve a minimum energy efficiency rating of band C by 2030.
"Thanks to government support, the number of homes with this rating or above has already gone from 13% in 2010 to 46% and rising.
“Improving the energy efficiency of homes is the best long-term method of tackling fuel poverty, and that’s why we’ve committed over £6.6 billion in this parliament, with a further £6 billion committed to 2028, to ensure all homes meet EPC band C by 2035.”