Fuel poverty could increase by millions of households and people will die in cold homes, an alliance of charities has warned the government.
The 25 charities - including Save the Children, Age UK, End Fuel Poverty and Greenpeace - have called for urgent government action to tackle the energy bills crisis.
It comes as experts predicted rising wholesale costs will result in a 50% rise in bills from April, when the latest energy price cap takes effect.
Will cutting VAT on energy bills help consumers?
This could result in the gas and electricity for an average household rising to nearly £2,000 a year - compared to under £1,300 at the moment.
In a letter to Prime Minister Boris Johnson and Chancellor Rishi Sunak, the alliance stressed the need for insulation and clean energy funding to be increased, to help wean the UK off expensive gas.
Dan Paskins, of Save the Children, said: "The cost-of-living crisis, fuelled by soaring energy prices, is totally unsustainable and is hitting the lowest-income families the hardest.
"Parents we work with tell us that they're struggling to meet basic needs, leaving them having to make impossible choices between heating their homes and buying clothes for their children, and children are paying the price."
Dr Doug Parr, policy director at Greenpeace UK, added: "The twin imperatives of a gas price crisis and the climate crisis mean we need to get off fossil fuels as fast as we can whilst protecting people on low incomes.
"A windfall tax on oil and gas companies would be a fair way to help finance the transition as we exit fossil fuel production in line with advice from leading experts at the International Energy Agency."
On Monday, Mr Johnson confirmed he was "looking at" what could be done to reduce the cost of household energy bills.
Speaking to reporters during a visit to a pharmacy in Uxbridge he said ministers have "got to help people, particularly on low incomes".
A government spokesperson said on Friday: "We recognise people are facing pressures with the cost of living, which is why we are taking action worth more than £4.2 billion and supporting vulnerable households through initiatives such as the £500 million Household Support Fund and Warm Home Discount.
"The Energy Price Cap is currently insulating millions of consumers from high global gas prices. We'll continue to listen to consumers and businesses on how to manage the costs of energy."