Non-renewable energy demand reduction and positive energy buildings in Southern Europe’s urban forms

The challenge of achieving a significant reduction in greenhouse gas emissions within a short timeframe necessitates extensive renovations of the existing building stock to meet the target of zero-emission buildings (ZEB). This study explores the feasibility of such renovations through building-plant system simulations for typical urban forms found in Southern Europe, classified using the Local Climate Zones (LCZ) method. Envelope retrofitting, combined with the use of electric heat pumps, allows for substantial reductions in energy demand while eliminating the use of fossil fuels. Renewable energy generated by rooftop photovoltaic systems can cover up to 96% of electric demand in the best case scenarios. However, results indicate that fully eliminating the need for electricity imports from the grid is unfeasible. Consequently, the more attainable goal of achieving a Positive Energy Building (PEB) status is investigated. In this context, a new definition of PEB is introduced, balancing the exported PV energy exclusively against the non-renewable portion of imported energy. Even when this PEB condition is met on an annual basis, it is not consistently sustained on a monthly level. The study concludes that achieving a monthly PEB target requires not only building-specific interventions but also an increased share of renewable energy supplied by the grid.