ENERGY companies have increased the bills of low power users, including second home owners and young professionals, by more than 50%, three times their headline increases.

Npower has hiked gas bills for 30,000 customers by an average of 40%.

The worst hit customers are in the East Midlands, London and the northwest with increases of more than 50%.

British Gas raised its charges for people using low amounts of power by an average of 44% for gas and 46% for electricity. Its worst-hit customers in Kent and the Midlands have suffered an increase of 70% for electricity.

Eon raised its bills for 30,000 households using only a low amount of energy, which is charged at a higher rate, by 41%.

Allan Asher, chief executive of Energywatch, the consumer watchdog, said: “They are effectively penalising people for conserving energy.”

Low energy users are charged more per unit because power companies apply a higher tariff to the first few thousands kilowatts. They justify it by saying that it reflects the fixed costs of providing a service.

Alistair Nicoll, 55, a research manager at Sheffield University, is among those whose bills have increased dramatically.

In January, Npower raised its gas bills by an average of 17% a year. But Nicoll, who prides himself on saving energy by putting the gas heating on for just 20 minutes a day to heat his water, saw his gas bill rise by 31%.

“The house is very well insulated,” he said. “Because I am a careful user of energy I feel I have been penalised. ”

Npower sets its threshold for the first block of energy at 4,572kwh a year, while British Gas and Eon have lower thresholds for their most expensive tariffs, set at 2,670kwh.

Scott Byrom, of comparison site Moneysupermarket.com, said: “The steeper increases on tier one will mostly affect people living on their own in small flats such as young professionals or people with second homes.”

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