Buildings as active nodes: Studying the effect of retrofitting and distributed energy resources

This study investigates the combined impact of building retrofitting and distributed energy resource (DER) deployment on the efficiency and stability of urban low-voltage distribution networks. A synthetic residential district was developed using a bottom-up approach, aggregating dynamically simulated building energy profiles and mapping them to feeder nodes. Two models were used: a steady-state investment optimization model to size photovoltaics (PV) and battery systems under net billing, and a detailed dynamic simulation to assess power flows and voltage regulation. This enables a spatially resolved analysis linking building-level demand, district energy planning, and grid dynamics. Results show that retrofitting reduces total electricity demand by 32.7 %, heating loads by over 50 %, and peak load from 201 kW to 113 kW. Aggregated PV-battery systems are more cost-effective than decentralized installations. In the decentralized setup, weighted self-consumption rates reached 46.2 % and 56.1 % in the reference and renovated cases, while the aggregated configuration achieved 51.2 % and 60.2 %, respectively, with shorter payback periods (∼6.4 years vs. 7.4–9.9 years). Despite the shared use of resources, electricity imports per building decreased under aggregation, reflecting higher autonomy; for instance, imports in unrenovated apartments dropped by 10.7 %, while the allocated CAPEX share declined from 4085 € to 3730 € (−8.7 %) due to more efficient system sizing and economies of scale. Dynamic simulations showed that Q/V control reduced RMS voltage deviation by 10.7 %, variability by 16.7 %, and ensured 100 % compliance with voltage limits. The proposed framework demonstrates the benefits of coordinated retrofitting and DER aggregation in enabling cost-effective decarbonization, improved self-consumption, and enhanced power system resilience. • A bottom-up method combining retrofitting and DERs in a unified district-scale modeling approach. • Aggregated DER deployment cuts costs and boosts self-consumption to 60 %. • Retrofitting and DERs jointly reduce peak demand by 43.8 % and CAPEX by 30 %. • Q/V control enables full voltage compliance with no added grid infrastructure. • Provides integrated techno-economic and dynamic assessment for urban energy systems.