This paper refers to a project research of an office building in a cold climate, which objective is to achieve optimized energy standards by applying integrated design strategies. A theoretical model is proposed, and the formulation begins with a morphological analysis. Subsequently, thermal, light and ventilation criteria are integrated; analysing the energy demand throughout the design process. The model is compared with a reference case. As a result, the optimized model achieves a significant reduction in energy demand, and better thermal / visual performance. It concluded that the application of the integrated design, with the support of assisted simulation tools, allows to optimize the energy performance of a building in the design stage.