Multi-Objective Design Optimisation of District Energy Supply - The Influence of Different Domestic Hot Water Concepts

Abstract

The supply of districts with electricity and heat can be designed in a variety of ways. This concerns the technical building equipment on the one hand and the sizing and operational management of energy-generating and energy-storing systems on the other hand. We used the “Model Template for Residential Energy Supply Systems” (MTRESS) to simulate and optimise supply concepts with respect to energy costs, CO2 emissions, and own-consumption using the example of the Helleheide neighbourhood. In the study, district heating network supply concepts based on 80 °C for direct domestic hot water supply, 40 °C with reheating for water treatment and legionella prevention and 40 °C without reheating but on-demand heat exchangers or ultra-filtration are compared. We find that most optimal solutions strongly integrate the heat supply with the electricity sector, with solar thermal supply being an exception to this general trend. Furthermore, operation and sizing of energy supply systems can have a bigger impact on both emissions and total costs than the actual choice of the technologies.