Of the 36 per cent of people who said they could not afford their power bills, eight in 10 (80 per cent) cited rising energy costs as a reason, the Citizens Advice Scotland (CAS) survey found.
Meanwhile, almost two thirds (65 per cent) said the rising cost of living was an issue – while 40 per cent said low incomes were an underlying problem.
Just under a quarter (24 per cent) said that their home being hard to heat was a factor.
CAS said it comes as people face a “perfect storm” this winter, with rising energy bills following the increase of the energy price cap, the crisis in the energy market seeing some suppliers go out of business, and the end of the Universal Credit uplift.
It has launched a Big Energy Saving Winter campaign encouraging people to get advice to tackle rising bills.
CAS Fair Markets spokesperson Kate Morrison said: “The fact that one in three people find their energy bills unaffordable is unacceptable, and what this research shows is that the underlying reasons can be varied and complex.
“From rising inflation and increased bills, to low incomes and homes that are hard to heat, people are struggling this winter – and these problems are likely to last well into 2022.
“The crisis in the energy market also means that some routes to lower bills simply aren’t available. For example, switching supplier will likely just lead people to a higher tariff.
“However, our message today is that the CAB network is here to help. We can check if you are entitled to any benefits or grants that you’re not currently claiming; we can talk to your energy company and re-structure any debt repayments you may have; and we can look at how better insulation can help you save money – and the planet at the same time.”
Pete McGinnie, 45, who lives in Edinburgh, is among those helped by CAS.
Mr McGinnie worked for many years in a call centre, before having to retire due to ill health.
For the last few years he has been living on disability benefits and has often found it difficult to afford the cost of living, particularly the cost of domestic energy bills.
Last year he sought help from his local Citizens Advice Bureau, who told him he could claim the Warm Home Discount, a grant that cuts your fuel bill by £140 per year.
He said: “For a while I was living day-to-day, using foodbanks and scraping together every penny. I was really struggling to cope. My house is not very good at retaining heat and I would often just stay in the one room, getting into bed during the daytime and just staying there, to try and save on my heating costs.
“But even then I was worried about how I was going to pay the bills. It was impacting my mental health and I went to some really dark places. Really dark.
“Then I went to Citizens Advice and they were brilliant.”
He added: “They told me I was eligible for something called the Warm Home Discount. I had no idea about this, and it was such a weight off my mind. It made a big difference to me.
“I’m still finding it hard at times, but this help meant I was able to heat my home again, and didn’t feel I had to switch the lights off and sit in the dark. I only wish I had asked for their help sooner.”
The survey of 1011 adults was conducted for CAS by YouGov in mid November.
Harry Mayers, head of Home Energy Scotland, said they were excited to be working with Citizens Advice Scotland on the Big Energy Saving Winter campaign again.