This office design project is located in the hot climate of Saudi Arabia and aims to achieve net zero energy status. Unlike the existing buildings in the city, the design adopts passive strategies like small openings, optimum orientation, effective shading and very high insulation standard to reduce cooling energy demand. The energy demand of this office is reduced to a minimum using the effective combination of active and passive design systems. EcoThinking supported the design team of local architects and engineers to develop a lighthouse project in the field of highly energy efficient buildings in the region. Using energy simulation from the early design stage, passive design strategies were evaluated and selected. An highly efficient HVAC and lighting system supported by a solar system that generated green electricity, this office design can reach an energy performance index of less than 20% compared to the conventional design in this hot climate region.