Disclosed herein are an energy saving method based on a confidence interval and an apparatus using the method. The energy saving apparatus based on a confidence interval includes an energy saving performance analysis unit for generating energy saving performance data for each of one or more control modules included in a target system for which energy saving is to be performed, a confidence interval reading unit for generating confidence interval data for each of the one or more control modules, and an energy saving execution unit for establishing an energy-saving policy using the energy saving performance data and executing energy saving for each of the one or more control modules using at least one of the energy-saving policy and the confidence interval data.