Optimierungsbasierte Extraktion und Bewertung von Planungsregeln für Wärmepumpensysteme in Einfamilienhäusern

RWTH Publications (RWTH Aachen)

Abstract

The ongoing climate change necessitates the decarbonization of the building sector through electrically powered heat pumps. However, economic, technical, and societal challenges hinder the widespread market penetration of heat pump systems. To address these challenges, planning should be both integratively optimized and as straightforward as possible. This dissertation therefore investigates the extraction and evaluation of practical planning rules from integrated planning optimizations. For this purpose, detailed, experimentally validated simulation models for the coupled operation of buildings and technical systems are developed. Planning decisions are optimized using simulation-based surrogate optimizations. The simulation scenarios are designed through optimally planned experiments to enable the extraction of generalizable rules based on a few practical input parameters, expressed as linear regressions of power laws. The deviation from the optimal planning results is quantified to evaluate these rules. Air-to-water heat pump systems in single-family homes serve as the application case. Through an analysis of planning practices and research, gaps in the fields of technology choice, system sizing, hydraulic integration, and operational strategies are identified and addressed. For technology choice, critical electricity-to-gas price ratios are determined for monoenergetic and hybrid heat pump systems, beyond which heat pumps become advantageous compared to gas condensing boilers. Moreover, results show that neglecting photovoltaic systems during the sizing of heat pumps and buffer tanks is permissible. Regarding system sizing, practical rules for determining the bivalence point are derived, highlighting that limited manufacturer data can lead to suboptimal sizing outcomes. Moreover, existing rules lead to average total cost increases of 10 %. Heat load estimations are shown to be reliable only when multiple measurements or precise heating limit temperatures are available. Additionally, small buffer tank volumes are generally found to be optimal. However, factors such as defrosting cycles and flexibility requirements emphasize the overall necessity of buffer tanks. For hydraulic integration, it is demonstrated that the configuration of the auxiliary heater is only relevant when operated simultaneously with the heat pump. Regarding operational strategies, non-predictive and predictive rule-based approaches for photovoltaic surplus utilization and nighttime setback are developed. The results show that nighttime setback is not recommended without smart thermostats or adaptive controllers, however, suitable controls can achieve savings in specific scenarios.

Authors 1

1. Fabian Römer corresponding Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen