Economic modelling of residential energy communities, including thermal flexibilities: a business case for prosumers and grid operators?

The increasing decentralisation and volatility of electricity generation and consumption pose significant challenges for distribution grids. The concept of energy communities leveraging demand-side flexibility is emerging as a promising solution. However, the economic viability of such concepts remains insufficiently understood. This paper presents a modelling approach to evaluate the cost-saving potential of flexible assets within energy communities and assess how different grid tariff structures influence their operation and impact on the grid. A key contribution is the integration of thermal building inertia into a linear optimisation model, achieved through coupling dynamic building simulation with an economic dispatch framework. Applied to a Swiss residential case study, the model quantifies cost savings from various flexibility strategies and local energy trading. The results show that collective self-consumption—without any peak power pricing—can reduce peak grid loads by approximately 8%. Furthermore, implementing a community-level peak power tariff achieves optimal peak shaving of up to 10%, while building-level peak tariffs are found to be counterproductive. In the context of the specific case study, the findings highlight how targeted tariff designs can incentivise both economic efficiency and peak-reducing behaviour at the energy community's common grid node.