The most frequently used technique for dehydration of dairy products is spray drying. This is an effective method to preserve biological products as it does not involve prolong exposure of materials to severe heat treatment. Due to the high energy cost of the process of the spray drying, a more rigorous understanding of spray-drying based on physico-chemical and thermodynamic properties is necessary. Recent advances in the understanding of product behaviour toward water transfer with the development of a desorption method make it possible to give several answers to the following question: What is the best strategy to anticipate, to calculate and to optimize the energy costs of spray drying according to the physico-chemical properties of the dairy concentrates? The strategical approach can be developed on the knowledge of the thermodynamic parameters of the spray dryer coupled to physico-chemical characteristics of the concentrate. The software SD2P® (Spray Drying Parameters Simulation & Determination) developed by Schuck et al. (2009) is a way, among others, to predict the value of these parameters when they are not known. The combined results provide more precise determination of spray-drying parameters (including inlet/outlet air temperature, mass/powder flow rate, powder temperature, etc.), powder state during spray-drying (stickiness) and the cost of spray-drying. Several cases will be presented to show the interest of this strategy in order to have an idea of the spray-drying energy cost according to many parameters such as the nature, the temperature and the total solid of the dairy concentrate, the percentage of drying in a fluid bed, the weather conditions, the energy losses in the spray dryer and the cost of the Kwh.