Energy transition buildings: A representative case study of refurbished single household shifted to full electric utilities combined with PV, wind and battery storage

The objective of the paper is a comprehensive energy and material rarity analysis of a representative example of household shifted to fully electric utilities, supported by uncommon combination of photovoltaic and wind renewables, complemented by battery storage. The manuscript provides figures of optimal battery storage sizing, complementarity of PV and wind resource and material rarity impact assessment, in a combined manner unavailable in literature. The approach and the considered example are generalizable to the wide category of single households and/or accommodation facilities in suburban areas, the countryside, the mountains and holiday resorts. The manuscript analyses the dynamic behaviour of a moderately refurbished single-family household located in a country/suburban area of central Italy, grid-connected and fully electrified through a heat pump combined with Photovoltaics, Wind Turbine (PV/WT), and a Battery Energy Storage System (BESS). A dynamic model based on 12 representative monthly days was developed to evaluate the seasonal thermal and electrical behaviour of the building. It was validated against measured PV/BESS data from an existing case study, characterized by its overall pre-/post-refurbishment transmittance U. To avoid costly and invasive masonry interventions, the existing high-temperature heaters were preserved, and a high-temperature Heat Pump (HP) was adopted. The seasonal simulations enabled the optimization of the Battery Ratio (BR), defined as the BESS-to(PV+WT) size ratio, to maximize the renewable fraction (Fr). Depending on the configuration, Fr ranged between 58.5 % and 65.6 % without WT, and increased up to 76.4-87.9 % with WT. The daily deficit associated with a PV string anomaly was quantified at 1-4 kWh under clear-sky summer conditions. Finally, an element rarity (TR) assessment was carried out for HP, PV, WT, and BESS as a complement to standard sustainability metrics. The analysis highlighted a TR impact of 68.2 GJ for WT, 36 GJ for PV, and 21.3 MJ for HP, while a 7 kWh BESS reached 36.6 GJ, largely driven by cobalt (79.2 %). This study provides a comprehensive example of household energy transition, combining moderate and costeffective refurbishment strategies with an uncommon PV/WT integration, relying on data from a real case study. It also introduces material rarity as an additional sustainability indicator, with the aim of supporting more balanced design choices in the residential energy sector.