CHICAGO (AP) -- A consumer watchdog group says this summer's extreme heat boosted the bills of Commonwealth Edison customers by about $64 million.
Commonwealth Edison is a unit of Exelon Corp.
But the Citizens Utility Board also said Tuesday that customers could've reduced most of that increase by changing their habits. They could have saved money and energy by using fewer lights and drying clothes outside, for example.
The board's analysis was based on energy-usage data from the Department of Energy and a sample of more than 2,000 ComEd customers. The customers sampled are using CUBenergysaver.com, a free online service offered by the Citizens Utility Board.
Illinois consumers used an average of about 7 percent more electricity this summer compared to last. Customers using the online service showed a significantly lower increase of about 2 percent.