PSI - Issue 78

Rita Couto et al. / Procedia Structural Integrity 78 (2026) 1951–1958 Rita Couto / Structural Integrity Procedia 00 (2025) 000–000

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1. Introduction The European construction sector is experiencing a crucial change related to new perspectives and challenges, driven by the need to address both seismic vulnerability and energy inefficiency in its ageing building stock. Past earthquakes have showed the seismic vulnerability of European buildings (Ozkula et al. 2023; Ruiz-Pinilla et al. 2016; Verderame et al. 2011) and energy inefficiency is, at the same time, widespread, with approximately 75% of buildings performing poorly. The building sector alone accounts for 40% of the EU's total energy consumption and 36% of its CO₂ emissions. This dual challenge demands an integrated renovation strategy to enhance both structural safety and energy performance (Gkatzogias et al. 2022; Pohoryles et al. 2020). Despite growing awareness, current European renovation efforts have largely targeted energy upgrades, neglecting structural vulnerabilities. This fragmented approach may result in limited or short-lived benefits and increased risk in seismically active areas. In response, several studies have proposed integrated frameworks that address seismic retrofitting and energy renovation simultaneously (Bournas 2018; Calvi et al. 2016; Caruso et al. 2023; Clemett et al. 2023; Couto et al. 2024; Manfredi and Masi 2018; Marini et al. 2022; Pohoryles et al. 2020; Takeuchi et al. 2006, 2009). However, successfully implementing these strategies on a large scale requires the identification of high-priority provinces, municipalities, or hotspot areas, ensuring that seismic risk reduction efforts are integrated with objectives for energy and economic efficiency. In this regard, recent studies (Gkatzogias et al. 2022; Mucedero and Monteiro 2024) have developed regional prioritisation tools that combine single and multi-sectoral indicators, related to seismic risk, energy performance and socio-economic vulnerability aspects, to inform equitable intervention plans and favour funding in regions of higher needs. Portugal, as well as EU Mediterranean countries in general, aims for carbon neutrality by 2050 through national plans (RNC 2050, PNEC 2030), promoting energy renovations and efficiency measures such as insulation upgrades and energy performance certificates (Ministry of the Environment and Energy Transition 2019). However, much of the residential stock remains energy inefficient and structurally outdated. Although there have been no recent major earthquakes, Portugal remains at considerable seismic risk. In spite of significant ongoing research (e.g., Costa et al. 2010; Lopes et al. 2024; Silva et al. 2015a; 2015b; Sousa 2016; Xofi et al. 2024), a unified framework to address both seismic and energy risks still lacks. Socioeconomic conditions further exacerbate vulnerability, particularly for low-income households (Hallegatte and Walsh 2021; Mahbubur Rahman et al. 2023), underscoring the need for an integrated strategy that combines seismic, energy, and social considerations. Recognising this, a holistic prioritisation framework, demonstrated for mainland Portugal, is proposed herein, combining seismic risk, energy inefficiency, and socio-economic vulnerability. The resulting framework assesses the combined needs of the Portuguese residential stock to identify regions of highest priority. Through a multidisciplinary, indicator-based approach, it supports equitable, scalable decision-making and helps guiding resilient investments and policy planning for integrated risk and energy management. 2. Methodology The proposed methodology involves detailed characterisation of seismic risk, energy performance, and socioeconomic vulnerability across 18 regions of mainland Portugal. Each sector is quantified using specific metrics and indicators, allowing for a holistic understanding of regional vulnerabilities. Table 1 summarises the different metrics used to compute each indicator. Each indicator is obtained by assuming the same weight for each corresponding metric. Once all the indicators are quantified, the final step is to combine the individual sectoral indicators into four integrated multi-sectoral indicators: I I,S-E (Seismic + Energy), I I,E-G (Energy + Socioeconomic), I I,S-G (Seismic + Socioeconomic), and I I,S-E-G (Seismic + Energy + Socioeconomic). These multi-sectoral indicators reflect different possible combinations of seismic risk, energy performance, and socioeconomic vulnerability, and equal weight is assumed between different sectors. Fig. 1 depicts how the indicators are interrelated, showing the intersections between the different sectors.