Thermal energy storage is gaining importance within the framework of energy turnaround. It is required in many applications to supply heat at a constant temperature. Therefore, phase change materials (PCMs) are considered suitable storage media in these cases. In this study, a eutectic salt hydrate mixture with a phase change temperature of approximately 21 degrees C was used. An amount of 600 kg was divided into sealed impermeable bags and placed at different spots in a prefabricated wooden house. Temperature sensors were placed inside the PCM bags, inside the room, and in the outside air. Temperature data were collected over 10 months under real environmental conditions. Furthermore, the thermal contact between the PCM and the interior space was investigated. The design that comprises PCM installation into a wall with back-ventilation proved to have the highest heat transfer rate. In addition, a simulation model was developed and applied to some PCM assemblies in order to characterize the effect of larger amounts of PCMs on the thermal behavior over an entire year and to forecast the energy requirements of the system. The results indicated that salt hydrates are cost effective and have a significantly positive effect on the thermal behavior of prefabricated wooden houses. (C) 2018 Elsevier B.V. All rights reserved.