A life cycle framework for a new integrated classification system for buildings and the identification of renovation strategies that lead to an optimal balance between reduction of seismic vulnerability and increase of energy efficiency, considering both economic losses and environmental impacts, is discussed through a parametric application to an exemplificative case-study building. Such framework accounts for the economic and environmental contributions of initial construction, operational energy consumption, earthquake-induced damage repair activities, retrofitting interventions, and demolition. One-off and annual monetary expenses and environmental impacts through the building life cycle are suggested as meaningful performance metrics to develop an integrated classification system for buildings and to identify the optimal renovation strategy leading to a combined reduction of economic and environmental impacts, depending on the climatic conditions and the seismic hazard at the site of interest. The illustrative application of the framework to an existing school building is then carried out, investigating alternative retrofitting solutions, including either sole structural retrofitting options or sole energy refurbishments, as well as integrated strategies that target both objectives, with a view to demonstrate its practicality and to explore its ensuing results. The influence of seismic hazard and climatic conditions is quantitatively investigated, by assuming the building to be located into different geographic locations.

It is well-known that the existing building stock is responsible for non-renewable resource depletion, energy and material consumption, and greenhouse gas (GHG) emissions. Life cycle analysis (LCA) procedures have thus been developed, in recent years, to assess the environmental impact of construction and operational phases through the entire building life cycle. Furthermore, the economic, environmental, and social consequences of recent natural disasters have encouraged the additional integration of hazard-induced impacts into common LCA procedures for buildings. Buildings are however expected to provide the population with safe living and working conditions, even when hit by different types of hazards during their service life, such as earthquakes. Hence, next-generation LCA procedures should include not only hazard-induced impacts, but also the contribution of potential retrofitting strategies that may alter the structural and energy performances of buildings throughout their remaining service life. This study presents a life cycle framework that accounts for the contributions of initial construction, operational energy consumption, earthquake-induced damage repair activities, potential retrofitting interventions, and demolition (considering also its associated potential material recycling), in terms of both monetary costs and environmental impacts. The proposed methodology can be used to undertake cost-benefit analyses aimed at identifying building renovation strategies that lead to an optimal balance, considering both economic and environmental impacts, between reduction of seismic vulnerability and increase of energy efficiency of a building, depending on the climatic conditions and the seismic hazard at the site of interest.

The sustainable renovation of existing buildings is currently at the top of the agenda of the European Union. Sustainability is typically defined as the result of the interaction of environmental, economic, and social aspects, and it is now considered a major target objective in all sectors of our economy, including the construction one. The concept of sustainable renovation has changed significantly over time, leading to the current interpretation that considers the need to simultaneously improve safety and resilience against natural hazards and minimise energy and resource consumption, as well as to reduce impacts along the life cycle of the building. This manuscript presents insights into combined/integrated environmental and seismic retrofitting techniques and assessment methods for the sustainable renovation of the existing building stock, specifically focussing on those conceived according to a Life Cycle Thinking (LCT) approach. This manuscript goes beyond the current available state of the art by highlighting the evolution of the concept of building sustainability throughout time, as well as defining a comprehensive taxonomy of available retrofitting strategies, while also identifying common clusters among available research papers. This research effort is part of the mission of the European Association of Earthquake Engineering (EAEE) Working Group 15 (WG15), which focusses on ‘combined seismic and environmental upgrading of existing buildings”.

Given the current climate emergency and the ambitious targets of carbon emissions reduction, retrofitting strategies on existing buildings typically include reducing energy demand, decarbonising the power supply, and addressing embodied carbon stored in materials. This latter point redefines the role of engineers in the transitions towards a sustainable construction sector, being they responsible for designing low impact, sustainable and carbon neutral solutions. A Life Cycle Structural Engineering (LCSE) approach, inspired by the principles of Life Cycle Thinking (LCT), should thus be adopted for the sustainable renovation of existing buildings. Only recently have pioneering approaches been proposed, tackling multifaceted buildings’ needs, such as those related to energy consumption as well as seismic safety, but often disregarding LCT principles. This study presents a redefinition of the concept of LCSE for sustainable construction and a comprehensive review of available methods and tools to operationalise the LCSE approach in practice, focusing on the consideration of LCT principles in the retrofitting design process, integration of seismic loss estimation and environmental impact assessment, and implementation of integrated retrofitting strategies. The greatest ambition of this work is thus to boost a paradigm shift for building engineers towards an interdisciplinary perspective in building assessment and retrofitting.