A method for optimizing energy consumption in a data-processing system comprising a set of data-processing units is disclosed. In one embodiment, such a method includes indicating a set of data-processing jobs to be executed on a data-processing system during a production period. An ambient temperature expected for each data-processing unit during the production period is estimated. The method calculates an execution scheme for the data-processing jobs on the data-processing system. The execution scheme optimizes the energy consumed by the data-processing system to execute the data-processing jobs based on the ambient temperature of the data-processing units. The method then executes the data-processing jobs on the data processing system according to the execution scheme. A corresponding apparatus and computer program product are also disclosed.