Reduced-order models for assessing demand response with heat pumps – Insights from the German energy system

Heat pumps are regarded as one promising option for Demand Response (DR) in renewable-dominated energy systems. By activating the structural thermal mass of buildings, power consumption of heat pumps can be decoupled from heat demand. Assessing the system-wide DR potential from heat pumps requires adequate models to account for the thermal response of the building stock to flexible operation. In this study, reduced-order thermal response models of twelve representative German building types in three insulation states are provided based on grey-box modeling. The identified models reveal a good compromise between accuracy of the simulated indoor temperature (RMSE of on average 0.6 °C) and computational cost (acceleration by factor 250) compared to the complex building simulation software TRNSYS. Furthermore, these reduced-order models are employed in a case study to estimate the technical DR potential of heat pumps by passive storage at specified ambient conditions. Extrapolated to the future stock of German single family houses, the maximum shiftable heat pump load adds up to 57 GWel. The structural thermal mass of the building stock enables maximal 300 GWhel of electrical energy to be discharged at a very cold winter day and 185 GWhel to be charged at milder temperatures