The measuring equipments for thermal performance of the prefabricated Ondol panel using hot water was developed and the performance evaluation techniques of the Ondol panel heating system was improved. Indoor thermal environment was predicted using the simulation program to verify the applicability of the prefabricated Ondol panel. In order to analyze the actual conditions energy transmission system, some examples of the United States and Germany were investigated and the characteristics of several methods of energy transmission were surveyed. (author). refs., figs., tabs.