Sustainability assessment of energy services using complex multi-layer system models

Energy providing companies are facing legal restrictions concerning environmental targets effecting design and operation of their energy services. Thus, optimizing energy services based on sustainable criteria plays a crucial role in providing clean, affordable and profitable business solutions in the energy field. The aim of this work is to help decision makers in design and optimization of energy services through the development of a methodology which uses two energy services (district heating and thermal insulation) as practical design criteria, which are stated as cross-cutting technologies to increase sustainable heat supply. Within this approach, both the requirements and effects of policy targets are implemented for system configuration. For that, a multi-layer energy service system is developed and assessed using a case-study, where an existing decentralized reference system is substituted by a central biomass-fired plant. In addition, a new method, called ”method relation analysis” (MRA) is proposed, which provides a tool to investigate the effects of different evaluation techniques on the design of the energy system and is exemplary shown for carbon footprint and emergy analysis. This offers the possibility for analyzing the dependency of different assessment criteria and gives insight on how policy targets influence sustainable system configuration. The two energy services showe different outcomes in terms of sustainability. Raising heat from the biomass plant increases environmental, while thermal insulation mainly effects technological sustainability. Optimum design values for the biomass plant vary between around 60% of thermal load for carbon footprint and around 20% for emergy analysis. Carbon emissions always shows better results than the reference system. The proposed MRA assessment shows unique improvements for system analysis providing information on system comparison, assessment results and their behavior.