In a geothermal and desiccant assisted air conditioning system at Hamburg University of Technology covering thermal peak loads by means of phase change materials (PCM) is investigated. In the consequence of high ambient temperatures the cooling power of the soil can be exceeded and a backup system is necessary. In this study experimental data of a backup system consisting of PCM encapsulated in plates and placed in a rack is presented. A computer case fan is used to induce a volume flow through the PCM rack. Results show that the PCM rack is able to locally focus cooling operation and as a result improve thermal comfort perception. An air temperature reduction of approximately 0.7 – 0.9 °C at an average cooling power of 26.58 W can be achieved. The COP accounts for 6.65 with a corresponding electricity consumption of 4 W.