Nowadays, the energy consumption has a significant role in the entire life cycle of a building. The energy demands keep rising due to growth in population, increasing demand for healthy, comfort and productive indoor environment, global climate changing, and so on. This rapid increase in energy use in buildings represents a major issue especially in regions with extreme climate conditions. For instance, in tropical climates the major reason for the high energy consumption for any type of building is the use of air conditioning. Before the implementation of refrigeration technologies in the building industry and the increase of thermal comfort levels, designers in tropical climates used to tackle the climate conditions using natural methods to prevent the building from unwanted heat and to control the heat gains from the surrounding environment. Thus, this research investigate the possibility of designing a purely passive building in order to reduce at minimum the energy consumption of an office building in tropical climates, combining the bioclimatic approach and passive cooling strategies. In particular, the design objective is to define to what extent can the cooling consumption of an office building be decreased. Different design strategies are implemented and tested through Building Performance Optimization (BPO). In specific, two optimization rounds are run. The first to investigate the impact of envelope parameters, and the second to investigate the impact of the envelope and indoor comfort parameters on the cooling consumption.