The increasing use of renewable energy technologies for electricity generation in buildings will require a growing number of battery energy storage systems (BESS) to enhance the reliability of electricity supply. The increasing number of retired electric vehicle (EV) batteries, expected from the automotive sector, can match this demand as EV batteries can be used as BESS, considering that they have about 80% of their original energy capacity. In this context, the study aims at examining the system, consisting of a BESS made by retired Li-ion EV batteries, a photovoltaic plant (20 kW) and the electricity grid, that provides the electricity required by an existing nearly net zero residential building (25.000 kWh/year). The goal is to identify the optimal BESS size, expressed as energy capacity, for load match optimization and environmental impacts in a life cycle perspective. A BESS of around 46 kWh of energy capacity allows achieving significant results in terms of load match increase and environmental sustainability. The study includes an environmental assessment combining the load match analysis and the life cycle approach. It highlights the potential synergy inspired to the principles of the circular economy and of the industrial symbiosis, between the building and the automotive sector. (C) 2019 Elsevier B.V. All rights reserved.