The regulator said British Gas delivered 62.4% of its Community Energy Saving Programme (CESP) by the required deadline at the end of 2012, meaning thousands of households had to wait for energy efficiency measures, such as insulation, to be installed during the winter.
Ofgem and British Gas, which blamed bad weather as one of the factors behind the delay, said the £11.1 million penalty will be used to help vulnerable customers through energy efficiency advice and improvements.
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