Heat recovery plays an important role in increasing the efficiency of renewable energy facilities like biomass furnaces, solar power plants or biofuel combustion engines. As the overall efficiency of the facilities can be increased by recovering the energy. The available waste heat can be converted directly into mechanical energy, pressure or subsequently converted into electrical energy by coupling the expansions machine with a generator. The waste heat can be converted by Organic Rankine Cycle (ORC). Therefore, an expansion machine, e.g. a turbine is required. Also small amounts of waste heat can be recovered, if so-called micro turbines are used. Design and construction of such micro turbines always follow fixed rules. Aim of this work is to explain the rules how to design a micro turbine. Furthermore, our workflow and a software tool which follows these rules should be presented.