Measuring the impact of holistic energy retrofit strategies: Life cycle assessment aligned with level(s)

The building sector plays a significant role in global energy consumption and greenhouse gas emissions, prompting urgent action to align with climate-neutral objectives. Consistently, the European Union (EU) has set ambitious targets for reducing emissions and increasing energy efficiency in buildings, stressing the need for balanced strategies that go beyond operational energy performance and address life cycle impacts. To this end, holistic sustainability assessment methods, such as Life Cycle Assessment (LCA), and tools, like Green Building Rating Systems (GBRSs) and Level(s), are of utmost importance towards measuring and improving the sustainability performance of buildings. This paper applies building-level LCA, in compliance with Level(s) framework, to a real-case building retrofit under the HEART H2020 project. In particular, the retrofitting involves the integration of smart technologies, including smart fan coils and DHW boilers, thermal energy storages, DC heat pumps, photovoltaic tiles, a multifunctional converter, modular façade thermal insulation panels and components to retrofit existing windws. Here, a specific methodological approach is adopted, since the environmental impacts of each technology are scaled to one year of service, independently of any predefined reference study period. LCA results demonstrate significant improvements in the environmental performance pre- and post-retrofit: the total Global Warming Potential (GWP) is reduced by 73%, with a 90% reduction in energy-related GWP impacts. These achievements highlight the effectiveness of the adopted technologies in lowering both embodied and operational impacts. Overall, the findings contribute to the holistic understanding of sustainability in building energy retrofit projects and serves as a reference for future research in the field.