The number of homes becoming warmer and cheaper to heat under government-backed insulation schemes collapsed in 2013, according to the latest official statistics.
The drop, of more than 90% in the case of loft insulation, was described as serious by the government's own fuel poverty adviser and terrible by Labour.
The only way for households to cut energy costs permanently is by improving energy efficiency, but the new figures show that the number of efficiency measures enabled by government schemes plummeted in 2013 as new policies replaced those of the previous government.
According to the Department of Energy and Climate Change figures, 1.61m lofts were fully insulated in 2012, but in the year to the end of October 2013, the most recent data released, just 110,000 had been treated, a pro-rata fall of 93%.
For cavity wall insulation, measures fell from 640,000 in 2012 to 125,000 in the year to October 2013, a pro-rata fall of 77%.
The big drops accompanying the start of the coalition's energy company obligation (ECO) and green deal schemes in 2013 were predicted by the government's own impact assessments.
ECO schemes, which require energy companies to deliver energy saving measures, account for 98% of the measures installed in 2013, with the green deal delivering 2%.
"With a cold winter, rising energy bills and a worrying increase in winter deaths, the plight of the 2.4m households in England struggling with fuel poverty has never been more serious," said Derek Lickorish, chairman of the government's fuel poverty advisory group. "The only sustainable solution to end the misery and health problems of living in a cold home is to improve its energy efficiency through insulation measures. The government must change direction."
He added that it was "perverse" that the £50 curb on the £120 rise in average bills announced in the autumn statement was achieved largely by cutting energy efficiency schemes.
Caroline Flint, Labour's shadow energy secretary, said: "The best way to cut people's energy bills is to invest in insulation and save the energy that escapes through our windows, walls and rooftops.
"These figures show that not only has David Cameron failed to stop the energy companies from overcharging, the number of households getting help to insulate their homes has also collapsed. This terrible reduction in insulation measures could not have come at a worse time." Labour would replace the green deal and overhaul ECO, she added.
It has been clear for months that the government's ambitious green deal scheme has fallen well short of where ministers hoped it would be.
The number of green deal loans for home energy efficiency retrofits had reached just 458 by the end of November. Energy and climate change minister Greg Barker had said that fewer than 10,000 by the end of 2013 would cause him sleepless nights.
The original ambition for the flagship policy was to upgrade 14m homes by 2020 – described as the nation's biggest property improvement scheme since the rebuilding that followed the second world war.
Reacting to the figures, he said: "The green deal and ECO have been off to an encouraging start with around 336,000 homes already more energy-efficient.
"It's clear that many of Britain's householders are seeing the fantastic cost and energy saving benefits these schemes have to offer."
Addressing the low take-up of green deal loans, despite 120,000 home assessments having been done, he said: "It's perhaps unsurprising that the earliest adopters of the green deal are choosing to pay for measures themselves and keep all of the savings rather than use green deal finance." He added: "We will continue to make adjustments to both the green deal and ECO in the new year to improve the customer journey."
A spokeswoman for the Department for Energy and Climate Change said the earlier government schemes had been very successful and had enabled insulation measures in 8m homes since 2008.
She said the new ECO scheme was moving the focus to "harder-to-reach people and harder-to-treat properties", such as those requiring solid wall insulation.
However, government data from July 2013 showed 7.4m homes still had inadequate loft insulation, though only 236,000 had none at all, and 5.3m homes lacked cavity wall insulation.
Andrew Warren, director of the Association for the Conservation of Energy, a trade group, said of the drop in insulation measures in 2013: "It is total decimation."
He said that as a result at least 7,000 fewer people were employed in delivering insulation in homes than in 2012, despite ministers stating delivering greater energy efficiency was a top priority.
"I find it nauseating," Warren said. "A lot of people went out and set up new small companies and they have been completely sold down the river."
