 BRITISH GaS has been fined ?1m after it miscalculated how much of the electricity that it supplies to its business customers had come from renewable sources.  The company will also have to repay more than ?2.8m in rewards to the Government because it did not come as close to meeting its renewable energy targets as it previously claimed.  The energy regulator Ofgem said that British Gas Business would have received a "much higher" penalty had it not reported the error itself and co-operated with the investigation.  The error, which went unchecked for seven years before it was reported in May, was caused by British Gas Business's incorrect interpretation of the reporting requirements and insufficient procedures, Ofgem said.