In the new smart grid paradigm, the residential prosumers can more actively participate in the energy exchange mechanisms by adjusting their consumption through demand response programs and their own available local generation and energy storage system. On these bases, a new model of home energy management system (HEMS) is proposed and analyzed in this paper. Numerical studies show that the proposed HEMS is able to find the optimal operating scenario in different situations and to achieve a reduction of the billing costs by providing some electric flexibility to an aggregator or to a system operator.