Under plans to lower the voltage of energy grids across the north-west of England, about 45,000 homes can expect to shave £60 from their annual electricity bills. The scheme could save millions of pounds on energy a year and cut carbon emissions without people noticing any difference, says the local network company.

During “Smart Street” trials over four years, engineers for Electricity North West found they could carefully lower the grid’s voltage by enough to save on energy without noticeably slowing household appliances or causing light bulbs to flicker.

“Nobody noticed the changes until they were given their bill and suddenly found out they’d been using less electricity,” said Steve Cox, the company’s engineering director.

“If we reduced the voltage by a few percent, then a full kettle might take eight seconds longer to boil. If we boost the voltage, it might boil eight seconds faster. But within the typical time it takes to boil a kettle, say two minutes, this really isn’t noticeable.”

“Voltage control” is well established in some states in the US, but Electricity North West will be the first network in the UK to reduce its voltage towards the lower end of the normal 220V to 240V range.

The company will install highly sensitive devices that pinpoint the “voltage sweet spot” at which appliances use as little energy as possible.

“It’s a bit like a car on the motorway. Your car could run at anywhere between 10mph to 90mph, but it operates most efficiently at 50mph,” Cox said.

“We monitor how much energy our customers are using in real time, and how much power is flowing through the network, and then we regulate the voltage down to the most efficient level so that appliances keep operating normally but consume less energy,” he said.

The savings could provide a new carbon-cutting frontier for the UK as it moves towards its 2050 target to create a carbon-neutral economy. By being more energy efficient, Electricity North West could cut its emissions by up to 10%, saving 143,860 tonnes of carbon by 2050 – the equivalent of taking 2,570 polluting cars off the road every year.

The lower voltage could also leave more capacity on the energy grid to connect new sources of clean electricity, such as small-scale renewable energy projects, to help meet the rising demand of electric vehicles and heat pumps without adding carbon emissions to the system.

Helen Boyle, decarbonisation manager for the company, said: “Demand for electricity is set to double over the next 20 years, so we’re taking positive steps now to help the transition away from fossil fuels and make the low-carbon economy a reality.”

Cox said the company hopes to expand the trial from thousands of homes to millions in the years ahead. It is already sharing its research with other regional energy networks which may also choose to lower the voltage to save on electricity.