For refineries throughout the world, energy management is an important element for controlling total operating costs. Over the past decades there appears to be an urgent need to retrofit the existing Heat Exchanger Network (HEN) of Crude Distillation Units (CDU) to reduce the current utility consumption. A simple pinch design approach is proposed here to accomplish above-and-below-pinch HEN design by stage-model mathematical programming using GAMS software. The energy and capital costs of a heat exchanger network are both dependent on the pinch temperature or ?Tmin which is set as target prior to the design of a HEN. In this work, a retrofit potential program was developed using visual basic for application (VBA) to find the optimum pinch temperature in targeting step. Moreover, the program can automatically generate composite curves, and grand composite curve of the process hot and cold streams. An example; base-case HEN of crude preheat train, from Bagajewicz’s paper (2010) is used to illustrate this procedure and compare the results.