Influence of energy-use scenarios in Life-Cycle Analysis of renovation projects with Building-Integrated Photovoltaics – Investigation through two case studies in Neuchâtel (Switzerland)

Since tomorrow’s cities are already largely built, and as many of their buildings – with a low level of energy performance – will still be standing in 2050, urban renewal processes play an essential role towards the sustainable development of European cities. In this context, Building-Integrated Photovoltaic (BIPV) systems can potentially provide a crucial response for achieving long-term carbon targets. Functioning both as envelope material and on-site electricity generator, they can simultaneously reduce the use of fossil fuels and greenhouse gas emissions. Focusing on the architectural design, this paper presents the results of a multi-criteria evaluation in terms of Life-Cycle Assessment (LCA) and Cost (LCC) of different renovation and energy-use scenarios. The goal is to identify which strategies can allow to achieve the ambitious targets for the 2050 horizon by integrating into the design process: 1) Passive strategies, to improve the envelope through low-embodied energy materials and construction systems; 2) BIPV strategies, using innovative photovoltaic products as a new material for façades and roofs; and 3) Active strategies, adapting HVAC systems to improve the efficiency of the BIPV installation and reducing the dependence on the feed-in-tariffs to ensure the profitability of investments. An emphasis is placed on testing the impact of a proposed selection process of BIPV surfaces in order to maximise self-consumption and self-sufficiency, evaluating the effect of electricity storage systems with and without the possibility of injecting the overproduction into the grid. Our methodology and results are presented through the comparison of two real case studies in Neuchâtel (Switzerland). Proposing a new approach to address renovation projects of existing buildings in the urban context towards Low Carbon Buildings, the outcomes provide architects and engineers with advanced BIPV renovation strategies depending on the building typology, the architectural design goals and the level of intervention.