Paper Conference

Proceedings of Building Simulation 2021: 17th Conference of IBPSA


LCA optimal sizing of smart buildings’ energy system components considering flexible grid-footprints

Tobias Blanke 1, Markus Hagenkamp 2, Joachim Göttsche 1, Bernd Prof. Dr. Döring 2, Vitali Reger 3, Markus Prof. Dr. Kuhnhenne 3
1 FH Aachen, Solar Institut Jülich, Germany
2 FH Aachen, Germany
3 RWTH Aachen, Chair for Sustainable Metal Building Envelopes, Germany

Abstract: Life Cycle Assessment (LCA) is a crucial tool to reduce the environmental impact of buildings. Usually, the impact factors of the electrical grid interaction with a building are assumed to be constant over time during LCA. Due to an increasing amount of renewable energies in the electrical grid mix, the impact changes throughout the day and the year. In this publication, an approach is presented to consider these flexible grid impacts. This approach allows a more accurate evaluation of storage systems like batteries to compensate for such impact fluctuations. Therefore, a two-stage optimisation problem is defined. At the first stage, a surrogate optimiser optimises the building component sizes towards a small total impact factor (construction and operation). Considered components are a solar thermal system, photovoltaic (PV), heating/ cooling surface, heat pump, battery system, and two thermal storages. At the second stage, a Mixed Integer Linear Program (MILP) minimises the grid impact. It calculates the grid impact for one year for the component sizes chosen by the surrogate optimiser. This optimisation is done for eight different impact factors individually. The results show that for conventional calculations, batteries are not optimal from an LCA perspective. Considering impact fluctuations enlarges the battery size for all but the costs and Acidification Potential (AP) impact factor scenarios. The solar-based components’ size is virtually independent of the calculation method, as is the heat pumps rated power. In all but the AP scenario, the size of radiators in the room significantly reduces when considering fluctuating impacts. The total impact factor can be reduced for most impact categories by optimally exploiting variations in the grid interaction impact factor.
Keywords: Optimization, LCA, building energy system components
Pages: 391 - 398