Margaret Pracy is being charged extra for using too little electricity
An energy-conscious pensioner claims she is being "fined" by British Gas for using too little electricity.
Margaret Pracy, from Brighton, who has a pre-payment meter, made her home as energy efficient as possible and uses only about £5 of power a week.
Now British Gas is to charge her 54p extra a week, because her consumption has fallen below the minimum threshold.
It said it would speak to Mrs Pracy to explain the charges, which applied to a "very small number" of customers.
Brighton and Hove Green Party said Mrs Pracy's bill fell below the £9 threshold after she made improvements under the government's Warm Front initiative.
"It's complete madness and makes a mockery of insulation programmes," said Councillor Bill Randall.
Mrs Pracy said British Gas was undermining the government's attempts to save the planet.
"If I follow all the government's suggestions on saving energy, which we need to save, then I will be fined by my energy provider," she said.
British Gas said it had reduced its tariff for prepayment customers in November 2008.
"However, a very small number of customers who use very little electricity experienced a small incremental charge of 54p per week," it said.
"We will speak to Mrs Pracy to explain these charges and discuss any other energy efficiency measures for which she may be eligible."