In the energy transition the expansion of the amount of renewable energy resources requires new methods for the design of energy systems. To deal with intermittent energy production, different energy technologies and solutions are in development. Hydrogen is a main candidate for this goal. Using Fuel Cell or Battery Electric Vehicles as flexible power plants is a second potential solution. This thesis explores how these two concepts can be combined in an office environment. The goal was to design an effective, integrated energy and mobility system making use of renewable energy only. A simulation model was written to carry out techno-economic analyses on a set of concept system designs. These systems were designed in accordance with three scenarios that were analysed for two future years, 2025 and 2050. The scenarios were: hydrogen-based systems, electricity-based systems and combined systems. The model was applied to a case study of the Shell Technology Center Amsterdam, an office building in the Netherlands. In addition, the same analysis was done for a hypothetical case study featuring an average office building in the Netherlands. The results of each simulation are compared mainly by their System Levelized Cost of Energy, for which electricity, gas and thermal demands are taken into account. In the 2050 scenario, the system levelized cost for a hydrogenbased system is 0.056 €/kWh, for an electricity-based system it is 0.077 €/kWh, and for a combined system it is 0.049 €/kWh. The findings of this thesis implicate that hydrogen is a viable alternative to use as an energy carrier in office buildings and for seasonal storage of renewable energy. It can be used in combination with cars as power plants, which are mainly suitable for hourly energy balancing.