Based on the analysis of the coupling mechanism between the heating system and the building’s thermal dynamic process, this paper establishes a detailed dynamic simulation model for building heating systems and conducts experimental validation. It analyses the node temperature changes, heat release, and response times of multi-thermal storage units (such as interior and exterior envelopes, furniture, etc.) during demand response periods, and discusses the impacts of different heating terminals. The results show that as the outdoor temperature drops, the heat release rate of each thermal storage unit accelerates during the demand response phase. The heat release time constants for both radiant floor heating systems and radiator heating systems are greater than 110 hours. Due to the thermal comfort constraints of indoor temperature regulation, the heat release times for radiant floor, radiator, and fan-coil systems are shorter than 22, 12, and 4 hours, respectively, with the system’s passive heat storage and release efficiency being below 20.17%. The larger the proportion of radiant heat from the heating terminal and the higher the outdoor temperature, the greater the activatable heat release of the system. The activatable heat release of the radiant floor heating system is approximately 2.5 to 3.5 times that of the fan-coil system.