In order to support energy efficiency improvement, it is essential to monitor the energy performance and to make benchmarking with similar process or related Best Available Techniques. Among different key performance indicators that compare similar processes, the most relevant for the industrial sector is the specific energy consumption (SEC). With regard to the energy demand in an industrial process, a variable and fixed portion can generally be distinguished: as a direct consequence the amount of energy used per unit of product (SEC) usually decreases while the production rate increases. It should be noted that often production processes face variable demand over their utilization. Aim of this work is to propose a novel decision model to support the identification of the more suitable investment in energy efficiency given the variable demand expected, explicitly considering that the effect of investments in energy efficiency can be categorized in two main categories: those shifting the SEC curve and those flattening the SEC curve.