British Gas has launched an unlimited dual fuel energy trial tariff which offers customers a fixed monthly direct debit regardless of the amount of energy they use.

The big six supplier said it will buy enough renewable electricity to match customers’ usage and offset double the carbon footprint of the gas they consume.

A statement on the company’s website said: “Our unlimited tariff works with your smart meter to put you in control of your bills. So when you need to turn on the fan on a hot day or the heating on a chilly night, you can relax as your bill will stay the same.”

But an energy analyst has warned the new tariff risks “undoing years worth of progress” in reducing the amount of energy used in homes.

Jonathan Marshall, head of analysis at the Energy and Climate Intelligence Unit said: “Falling energy demand in the UK is a major driver behind lower bills, lower emissions and lower waste. By offering a tariff that incentivises profligacy, British gas risks undoing years worth of progress that has seen the amount of energy we use to heat and power our homes drop.

“It also sends a bad message to customers, that efficiency is something not to worry about. Rather than promoting wastefulness, British Gas could be minded to boost the rollout of insulation, efficient boilers and air-tight windows, which can shave hundreds of pounds from annual energy bills, benefitting individual consumers and the country in general.”

Although the tariff is labelled as unlimited, the terms and conditions include a “reasonable use” policy.

Customers will be assigned to one of three usage groups – high, medium and low – based on their historical consumption. Those whose usage exceeds the upper limits of these bands by more than 50 per cent may be moved to another tariff.

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