This paper presents an approach to the inclusion of the degradation of the equipment due to ramp-up and shut-down in the optimization of the response of chemical and power plants to the variation of the prices on the market for electric power. The state-of-the-art approach neglects the influence of the operating strategy on the degradation of the plant equipment and leads to aggressive responses to the price levels. The proposed Mixed Integer Linear Programming formulation maximizes the profit of a combined heat and power plant taking into account the reduction of the lifetime of the equipment that results from the operating strategy. A case study demonstrates the benefit of the proposed approach.