A system for treating objects includes a device for tempering objects in which a tempering tunnel having at least one air outlet and at least one air inlet is arranged in a housing. At least one heating unit, in which a hot primary gas flow can be generated, is assigned to the tempering tunnel, wherein the hot primary gas can be guided into a circulating air heat exchanger, in which air from the tempering tunnel can be heated by hot primary gas as circulating air, which can be fed back to the tempering tunnel in a circuit via the at least one air inlet. The heating unit is coupled in the manner of a combined heating and power plant to an electric generator in such a way that electrical energy is produced during operation of the heating unit.