How refrigerant cycle modeling shapes the techno-economic analysis of centralized vs. decentralized heat supply systems for city districts

Heat supply systems can be divided into district and individual heating. For both, heat pumps (HPs) play a key role, and their future relevance can be assessed using dynamic simulations. This raises the question of which HP model is most appropriate and how model choice influences techno-economic decision indicators. This paper analyzes the impact of HP modeling on result variability and introduces a novel approach: the Unified Heat Pump Model (UHPM). The UHPM employs a unified parameterization, requiring no detailed knowledge of HPs while enabling the simulation of off-design operating conditions. Its COP estimation is validated against publicly available manufacturer COP maps, while its power estimation is validated using field monitoring data from five HPs. A techno-economic analysis is conducted for a residential district. The dynamic simulation represents the complete system, from building envelope to heat supply, and applies three HP models: UHPM, Carnot, and manufacturer-performance-map-driven. Key decision indicators include peak electric power, annual electric energy demand, and levelized cost of heat. The variability of results across the models ranges from −27.0% to 29.4% for decentralized systems and from −10.3% to 10.3% for centralized systems, depending on the indicator and building stage. This internal variability leads to overlapping decision indicators between system configurations. The UHPM enables consistent system comparison and reduces ambiguity. Results indicate that centralized systems are advantageous in terms of peak power reduction, whereas decentralized systems are more favorable for retrofitting from an economic perspective.