Across Europe and beyond, energy systems are undergoing a double transition: from fossil-based, centralized supply to renewable, distributed infrastructures, and from distant, utility-led decision making to locally grounded investments by heterogeneous actors. This thesis investigates how Renewable Energy Communities (RECs) can become a vehicle for both transitions by coordinating technologies, operations, and costs at the scale of districts and municipalities. The central research question is: how can RECs efficiently support the transformation of local energy systems, and how should expenses and benefits be allocated among stakeholders to ensure technical feasibility, fairness, and economic viability?

Methodologically, the work studies RECs along two complementary axes â technical innovation and economic integrationâ within a unified, bottom-up modeling framework that shifts the perspective from supplying energy carriers to fulfilling end-use energy services. On the technical axis, the framework evaluates options for building- and district-scale assets, along with efficiency measures, sector coupling, and grid integration strategies, and co-designs capacities and operations to leverage shared infrastructure. On the economic axis, the framework identifies stakeholders and business models, implements internal energy pricing for the community, and constrains actor portfolios to balance affordability for end users and profitability for capital providers.

Chapter 1 builds a territorial evidence base by linking energy services to the building stock and local resources in a GIS database, and clusters districts into archetypes to enable extrapolation. Chapter 2 models buildings as multi-energy hubs via a MILP formulation, generating a comprehensive set of feasible configurations under diverse contexts and flexibility strategies. Chapter 3 extends the hub model to districts through a Dantzig-Wolfe decomposition, quantifying the benefits of pooling prosumers, coordinating decisions, and deploying shared assets under grid constraints. Chapter 4 translates technical configurations into actor-specific cash flows by formalizing internal pricing and business models, thereby bridging design choices with implementable cost allocation and governance. Together, the chapters connect territorial heterogeneity, technology design, coordination mechanisms, and stakeholders alignment.

From the scientific perspective, the thesis contributes: (i) a data-driven clustering framework that typifies districts as collections of end users, enabling large-area REC studies; (ii) advances in building energy-hub design and operation that evaluate technologies and energy management through flexibility and storage options; (iii) a grid-aware district hub model using decomposition to capture the value of coordination and shared infrastructure; and (iv) an internal pricing and actor-portfolio formulation that operationalizes business models and fairness constraints within RECs.

Practically, the work presented promotes open science by delivering an open-access dataset (QBuildings) and an open-source decision-support tool (REHO) for buildings and districts, applied to the Swiss building stock and validated with utilities. These outputs foster transparent, reproducible research while informing policy and investment decisions for REC deployment at scale.