Britons have cut their gas and electricity consumption by more than 10% since October, in the first evidence of the impact of the energy crisis on household habits, according to two of Britain’s biggest suppliers.

E.ON, Britain’s second-largest supplier, and owner of Utility Warehouse have reported “double-digit” declines in recent weeks.

As households slash consumption in response to rising bills, Business Secretary Grant Shapps has written to industry bosses to say customers slashing energy use to save money shouldn’t face an increase in their direct debits.

Sharing a letter he sent to chief executives of UK energy suppliers over the weekend, he tweeted on Sunday: “Households shouldn’t see their direct debits go up when their energy use goes down.”

In the letter, Shapps said he was “disturbed” by reports that some consumers had been told their direct debits would increase “as they work hard to reduce their consumption to save money at home.” a time when household incomes are reduced”.

He added: ‘With other costs to households increasing, it is essential that we do what we can to help. I’m interested in understanding how you plan to ensure your direct debit system doesn’t overstate billing. »

Energy industry executives are watching closely to see if concerns about high bills translate into a significant reduction in usage this winter.

Michael Lewis, chief executive of E.ON, which has 5.6 million customers, said the provider was “seeing reductions of 10-15%” from seasonal averages in recent weeks.

“It’s a pretty big effect. We analyze our data and try to understand what is going on. These will likely be people turning the heat on for shorter periods of time or turning down the thermostat in their home. These are the two big levers.

Andrew Lindsay, managing director of publicly traded Telecom Plus, said gas consumption had fallen by around 10% in recent months and “we expect there to be a further drop in consumption as people self-regulate. We expect a further double-digit drop in consumption.”

Telecom Plus owns Utility Warehouse, which has more than 800,000 customers and offers low rates by bundling energy, broadband, mobile phone and insurance services.

Both Lindsay and Lewis said the abnormally warm weather in October and November made it more difficult to analyze consumer behavior.

Lindsay added, “We expect [energy reduction] to continue through the winter – for people to self-regulate, but they can’t self-regulate to zero. It’s over and there’s a big government campaign to encourage people to be energy efficient and that will definitely result in people being more careful which is the right thing to do. We have therefore taken this into account in our forecasts.

Ministers plan to launch a £25million public information campaign before Christmas to encourage people to reduce their energy use this winter. The wrangling over whether to run a campaign has spanned three prime ministers and split the Tory party, with some MPs including Liz Truss fearing it will be seen as a ‘nanny’.

The government is expected to suggest the public save energy and money with advice such as lowering the temperature of boilers and switching off electrical appliances rather than leaving them on standby. Similar campaigns have been underway in Europe for months as countries try to ease pressure on the gas network, strained by Russia cutting off supplies to Europe after invading Ukraine.

In the UK, National Grid has launched a program offering discounts for off-peak electricity consumption to reduce pressure on the grid.

Lewis said E.ON, which signed up to the initiative, had seen 21,000 households participate, and 70% of them had reduced their consumption enough to receive payments.

The government has stepped in to ease the pressure of rising energy bills through its energy price guarantee, which caps typical annual household bills at £2,500.