As energy prices and the cost of living soared, 2022 saw a record fall in the amount of gas people in Ceredigion, Gwynedd and Powys used to fuel their homes, new figures show.
Campaign group National Energy Action said households may be reducing their energy use to "dangerously low levels", and called on the UK Government to provide more support to the most vulnerable.
Department for Energy Security and Net Zero figures show Ceredigion residents used 91.6 Gigawatt hours (GWh) of gas in 2022.
This was a 14.1 per cent fall on the year before, the largest decrease in domestic gas usage since comparable records began in 2006.
Meanwhile, Gwynedd residents used 299 Gigawatt hours (GWh) - also a fall of a 14.1 per cent.
And in Powys, residents used 296 Gigawatt hours (GWh) - a drop of 13.1 per cent.
The City of London – which has a very small residential population – was the only area in Great Britain that did not see a record drop in the amount of domestic gas used.
Nationally, domestic gas use fell by 12.7 per cent in 2022 – also the highest decline in 16 years – which the Department for Energy Security and Net Zero's report said is "likely related to elevated energy prices as well as the generally high cost of living".
Peter Smith, director of policy at National Energy Action, said the record fall is "very striking".
He said some of the fall could be due to people reducing needless energy use, but warned it is likely many of the 6.5 million households in the UK "are having to cut their energy consumption to dangerously low levels".
Mr Smith added: "We are continuing to call on the UK Government to provide more support to protect the most vulnerable people. We know millions of people are no longer getting the support they need to offset the worst ongoing impact of this energy crisis."
Domestic electricity use also saw a record fall nationally, with the amount used in 2022 down by 8.2 per cent on the previous year.
In Ceredigion, 137 GWh of electricity was used by residents to power their homes.
This was 9.1 per cent down on 2021, and also a record fall since comparable figures began in 2006.
In Gwynedd, 213 GWh of electricity was used and in Powys, 226 GWh - both down 10.8 per cent.
The DESNZ said it "recognises the cost-of-living challenges families are facing", and is providing £104 billion of support with bills.
A spokesperson added: "Thanks to our Warm Home Discount, 3 million low-income households are expected to benefit from £150 targeted support this winter.
"Our Energy Price Guarantee remains in place to protect people until April this year, and we’re continuing to help the most vulnerable, with 8 million households expected to receive a £900 cost-of-living payment, while those on disability benefits will get an extra £150."