Energy giant British Gas has been handed an £11.1m fine by industry regulator Ofgem because it failed to meet energy saving and environmental targets.
Ofgem's Consumer Energy Savings Programme (CESP) sets targets for power companies so that people in low income areas can expect a reduction in their bills. This is achieved by providing customers with loft and wall insulation and new boilers.
British Gas met 62.4% of the targets, but this was deemed insufficient by Ofgem. It was fell just short of emission reduction goals set by the watchdog, with a score of 99%.
Sarah Harrison, Ofgem's senior partner with responsibility for enforcement, said: "British Gas' failure to deliver two environmental obligations on time is unacceptable. Thousands of households had to wait for energy efficiency measures, like insulation, to be installed during the winter.
"The payment reflects British Gas' failure to meet its obligations on time but also recognises its commitment to put things right."
Claire Miles, managing director of British Gas New Energy, said: "We're hugely committed to the success of our energy efficiency programmes and are sorry that we missed the December 2012 deadline. However, we're pleased that in the end we managed to help more vulnerable people under this scheme than was required."
News of the fine comes a week after power generation firm Drax was hit with a record £28m penalty for not reaching goals under the same scheme.