One of the challenges for engineers designing indoor environments is merging the need for energy savings with providing thermally comfortable conditions for the occupants. Since the best way to evaluate thermal comfort, i.e. direct enquiry, is at the same time the most costand time-consuming one, various modelling tools are widely used. However, in order to assess complex heterogeneous environments created by novel building systems, there is a need for more sophisticated and precise tools. In this paper, we present a new human simulator methodology for indoor environmental research, combining three tools to predict thermal sensation, namely, a thermal manikin, a thermoregulation model, and a thermal sensation model. Thanks to the thermoregulation model's control, the thermal manikin is capable of mimicking the thermo-physiological response of a human exposed to chosen environmental conditions, which provides reliable input data for advanced thermal sensation models. Along with presenting this concept, the performance of a commercially available human simulator was demonstrated on five validation examples representing office-like conditions for which thermal sensation was predicted with satisfactory accuracy. Based on the presented results, we discussed the capabilities and limitations of human simulators for indoor environment research such as the benefits of performing measurements directly in the assessed environment with real garments, and the challenges related to the manikin's accuracy. The presented human simulator approach is suitable to apply in the building's design process, as well as the development of new solutions for conditioning indoor spaces, and can support the evaluation of existing buildings.