Keywords

1 Introduction

The built-up area in Europe covers 25 billion square meters, 20 billion of which were constructed before 1990. Most of buildings in Europe are old, posing an urgent need for renovation to align with the goals of multidimensional European and international policies.

Buildings are responsible for 40% of the energy consumption and 36% of the total greenhouse gas (GHG) emissions in the European Union (EU), whereas 75% of the EU building stock is considered energy inefficient (European Commission 2020). These figures pose the issue of the environmental performance at the top of the agenda for the renovation of the existing building stock, also supported by the New European Bauhaus initiative (European Commission 2021) to create sustainable, beautiful and inclusive living spaces, in line with the European Green Deal priority (European Commission 2019).

The construction industry, as a main energy consumer and a foremost contributor to greenhouse gas emissions, has been undergoing a “green revolution” in the recent years. Sustainability has become a prominent issue, and environmental methods such as footprint schemes and Life Cycle Analysis approaches are being considered in the design and in the rehabilitation of buildings.

Furthermore, most of the buildings that are located in seismic prone regions of the EU were built without modern seismic design considerations and thus lack adequate seismic safety. Consequently, extensive building damages, as well as fatalities, severe injuries and significant economic losses are expected in the aftermath of a potential earthquake, as demonstrated in EU regions with moderate-to-high seismic hazard. However, regions with lower risk (e.g. Spain, France) should not be left behind.

The rehabilitation of the existing buildings need to satisfy modern criteria in terms of energy efficiency and environmental performance, within the context of adequate safety requirements. Tackling all these needs at the same time is cumbersome, as demonstrated by several experiences during recent earthquakes, where the sole improvement of energy performance has been vanished by seismic-induced damages.

Whereas many methods exist to measure the energy efficiency and environmental performance of buildings (Menna et al. 2022), few of them can be applied in the practical design of the rehabilitation, and can be easily combined with the structural and seismic design.

An effective way to achieve building sustainability should consider and integrate environmental issues in the earlier design stage, when the durability, probabilistic reliability and safety of structures are involved. These are correlating and complementary parameters, parts of the same whole and, thus, they need to be considered and addressed together. Therefore, to move towards sustainability, an integrated design approach is deemed essential that allows building assessment in a multi-performance perspective.

A method, to be used in the design or in the rehabilitation of buildings, which combines both energy efficiency/sustainability and seismic safety has been developed. The method, named Sustainable Structural Design (SSD) or SAFESUST approach, is based on purely economic parameters, and is briefly presented in the following.

2 The Sustainable Structural Design Method

The Sustainable Structural Design (SSD) method is conceived as a supporting tool for the general process of building design that takes into account technical-structural aspects along with environmental ones during the life cycle of the structure. It aims at optimising the process of building design in terms of structural and environmental performances, configuring a design method for both safety and sustainability (Romano et al. 2013, Lamperti Tornaghi et al. 2018), a goal also expressed by other authors (Marini 2017).

The SSD method has been developed to include, in economic terms, the structural, energy, and environmental performance components of the construction or rehabilitation, maintenance, use and final dismantling of a building throughout its expected lifetime. This includes the cost of construction/rehabilitation, the expected losses due to seismic damage, including costs associated to downtime, the energy costs, as well as the expected environmental impact in terms of GHG emissions, commonly expressed as equivalent carbon dioxide (CO2) emissions, also converted into monetary units.

The SSD method should not be considered as just-another-framework to perform multi-criteria evaluations; its ambition is sharing and coordinating the best practices already available and used by different experts in the building sector, as well as owners and investors.

The framework of the SSD method consists of three main assessment steps: (i) energy performance assessment, (ii) structural performance assessment, and (iii) Life Cycle Assessment (LCA). Subsequently, the outcomes of the three previous steps are combined into a global assessment parameter in monetary units, defining the fourth and final step of the method. Each stage is briefly presented in the following.

2.1 Energy Performance Assessment

Having made it clear that the method is expressed in monetary terms, it does not come as a surprise that a fundamental component is the assessment of the cost relevant to energy performance. This is clearly understood by owners and investors, and is traditionally considered in terms of return of investment when compared with the rehabilitation costs.

When we look at the entire life cycle of a building there is much more than the operating energy. Other energy components might refer to embodied energy for construction or rehabilitation as well as demolition energy. These are accounted for in the subsequent third step of the SSD method, i.e. the life cycle assessment (LCA).

The reason to limit the energy performance assessment to the operating energy is dictated by the fact that it might already include some forms of carbon tax, which should correspond to the associated environmental impact. Moreover, the energy performance assessment is routinely performed by professionals, mechanical, electric and plumbing (MEP) engineers, who mobilise specific competences that are different from the competences required for the LCA.

The final outcome of the energy performance assessment is thus the total expected operating energy for the building. Even though the uncertainties associated to the evolution the costs of each source of energy cannot be avoided, one should be aware that the operating energy represents the largest portion of the total environmental burden for existing buildings. This is precisely why much effort is being put into reducing the operating energy of buildings. The more this is reduced, towards nearly Zero Energy Buildings (nZEB), the more other energy contributions will gain in importance.

2.2 Structural Performance Assessment

The conceptual framework is linked to the performance-based assessment methods, which have been gaining big interest in the field of structural engineering. This interest originates from the successful implementation of the Performance-Based Earthquake Engineering (PBEE) method from the Pacific Earthquake Engineering Research (PEER) Center (Deierlein et al. 2003). The PEER’s PBEE method has been fundamental in addressing the importance of integrating loss-assessment within structural design. However, such method seems too complicated to be applied to ordinary projects due to complex probabilistic relations and high number of parameters (Tsimplokoukou et al. 2014). Considering the latter, a simplified Performance-Based Assessment (sPBA) method has been introduced.

The method (Contini et al. 2008, Negro and Mola 2017) is based on a simple piece-wise integration of the total probability equation.

The first step is the definition of a number of limit states and the associated damage costs (repair costs and downtime costs). An inter-storey drift value is then associated to each limit state and, with reference to a push-over curve, the corresponding peak ground acceleration (PGA) value is identified.

Referring to the relation between return periods and peak ground acceleration values which is typically provided by the seismic code, the return periods are associated to each limit state and from the return periods the probabilities of exceedance for the assumed lifespan of the building are computed. The total expected cost can then be calculated as the sum of the products of the intervals between the probabilities of exceedance by the associated costs.

It is worth noting that the sPBA method is somehow similar to the method recently introduced for the calculation of the expected average annual loss (Ministero delle Infrastrutture e dei Trasporti 2017) in the Italian regulations to assess the seismic classification of existing buildings in the perspective of the so-called “Sismabonus” mechanism. The latter aims to provide fiscal incentives for fostering seismic retrofit of buildings. The main difference remains with the reference to the design lifespan of the building, rather than to the average annual values. The reference to the design lifespan makes the economic terms easier to compare to the construction or rehabilitation costs, without the need to introduce return to investment concepts. Moreover, it is believed that the introduction of the concept of expected lifespan for a building (which might be different for different occupancies, should be left with the decision of the owner/investor, and might in many cases refer to the interval before a change in use or a major renovation rather than to the very dismantling of the structure) would lead to a more rational approach in the construction industry.

The method is particularly simple and can be implemented by a spreadsheet, the only demanding component being the evaluation of the costs associated to each limit state, which might strongly depend on the occupancy of the building (and might include downtime costs) and should be computed with the assistance of the owner of the building.

2.3 Life-Cycle Assessment

A conventional LCA analysis is performed using the common practices and according to the standard cradle-to-grave approach, compliant with the requirements and guidelines provided by the International Organisation for Standardisation (ISO) in the standard series ISO 14040 (ISO 2006a) and ISO 14044 (ISO 2006b).

The contribution of the operating phase is estimated by using the results of the previously conducted energy assessment and converting the total energy quantities into equivalent CO2 emissions.

The functional unit and system boundaries are defined according to the object of the SSD analysis, e.g., two rehabilitation alternatives or the rehabilitation vs. demolition & reconstruction.

The contributions of all the other phases are also expressed in terms of equivalent CO2 emissions. The result is the total amount of equivalent CO2 emissions throughout the assumed lifespan of the building.

2.4 The Global Assessment Parameter

The analysis has associated to each design or rehabilitation solution (which might also include the option demolition & reconstruction) a total cost, which includes the construction cost and the cost for the expected damage/repair/maintenance, the operating energy costs, plus the total equivalent CO2 emissions.

It is evident that the two quantities (i.e. costs and CO2) are not comparable, therefore it was decided to refer for the equivalent CO2 emissions to a unitary cost (equivalent carbon dioxide per tonne), e.g. the one currently linked with European Union Emission Trading System. Along this line, a total cost, which represents the global assessment parameter, can be associated to each design or rehabilitation option, so that the optimum solution can be identified.

It is once more the case to note that the analysis depends on the assumed expected lifespan (or the expected time before a major refurbishment or change in use).

The method has been applied to case studies for identifying the best option for the construction of a new building (Lamperti et al. 2018) or the best option for the refurbishment of an existing underperforming one (Dattilo et al. 2010).

The main advantage of the SSD method, arising from its being completely based on economic evaluations, is that it can support the traditional design methods rather than replacing them. The traditional actors of the design phase (architects, as well as civil, MEP and structural engineers) are assisted by additional practitioners, namely the LCA experts, in continuous interaction with owners/investors. Each outcome is expressed in terms of the same monetary units; therefore, decision makers can compare and evaluate all parameters, which are independently regulated by their respective markets (Fig. 1).

The method has also shown to be amenable to deal with actions different from seismic ones, e.g. fire or explosions (Iuorio and Negro 2020) or to be applied at territorial level (Caruso et al. 2017).

Fig. 1.
figure 1

SSD framework and involved actors (Lamperti Tornaghi et al. 2018).

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3 A European Pilot Project

The European Parliament recently entrusted the European Commission’s Joint Research Centre with a European Pilot Project “Integrated techniques for the seismic strengthening and energy efficiency of existing buildings”, aimed to define technical solutions that can reduce seismic vulnerability and increase energy efficiency of existing buildings, at the same time and in the least invasive way. This holistic approach provides significant environmental benefits by reducing CO2 emissions and the waste generated through building replacement actions, as well as minimizes economic losses and fatalities due to future earthquake disasters.

Key-objectives of the project regard the definition of tools and guidelines to simultaneously reduce seismic vulnerability and energy inefficiency of buildings, the stimulation to use integrated solutions, and the creation of awareness about the topic in the aim of prevention.

Several activities have been foreseen in order to achieve the Pilot Project objectives. EU existing buildings needing seismic and energy upgrading are first identified, and seismic and energy retrofit technologies are reviewed and assessed in a life-cycle perspective. Combined retrofit solutions are explored based on available technologies and recent scientific developments in the field of novel solutions. A simplified method for the assessment of the combined upgrading is proposed and applied to case studies of both residential and non-residential representative building typologies retrofitted with the investigated upgrading technologies. Seismic risk along with socioeconomic aspects and energy performance of buildings are assessed at regional level throughout Europe to identify regions where interventions are of higher priority. National, regional and local authorities, industrial associations and expert communities are involved in enquiries and discussions of relevant implementing measures (legislation, incentives, guidance and standards), technologies and methodologies for the combined improvement of seismic and energy performance of existing buildings.

Main outcomes of these activities are presented in the following. The results of the pilot project will provide scientific advice to support the development of an action plan, which shall supplement existing EU policies in the field of energy efficiency and disaster risk reduction.

3.1 Seismic and Energy Retrofit Technologies for Existing Buildings

The prioritization of the EU buildings most needing seismic and energy upgrading is first analysed as a crucial step to provide an overview of retrofit technologies to launch seismic safety and energy efficiency improvements across EU regions.

The EU residential building stock has been investigated by year of construction, floor area, and structural system according to available data provided by both the European and national statistical institutes, as well as the European projects (TABULA) and (NERA). Nearly 80% of EU dwellings were built before 1990 and more than 20% before 1945, thus the EU building stock is particularly ageing. Moreover, masonry and RC structures represent the EU buildings most needing upgrading.

Subsequently, an extensive analysis focused on mapping the EU territory to climatic and seismic hazard zones based on specific 2019 Eurostat heating degree days (HDDs) data and PGA range values according to the European Seismic Hazard Model 2013 (ESHM13) (Giardini et al. 2014), respectively. Thereby, representative EU countries characterised by moderate-to-high seismic hazard and high level of HDDs have been selected, namely Bulgaria, Croatia, Greece, Italy, and Romania. Germany has been also considered to provide a more detailed analysis by including a EU country with low-to-moderate seismic hazard.

Specific regions within the above-mentioned selected countries has been analysed by considering several combinations of seismic hazard and climatic conditions, building age, and period of implementation of seismic codes and energy regulations. Main results underline a potential to apply combined upgrading to at least 60–70% of the existing building stock in the selected countries. Furthermore, a focus on the Italian context pointed out that one third of masonry and RC buildings is located in areas with very high seismic and energy demand, thus urgently requiring combined retrofit.

Seismic retrofit technologies have been reviewed by focusing on global and local interventions. The overview of global retrofit strategies refers to solutions common to different building typologies, aimed at either reducing the seismic demand (i.e. seismic isolation, additional damping) or enhancing the seismic capacity. As for the latter, different solutions related to the provision of new RC walls, RC infills, steel braces, rocking wall systems, and external exoskeletons (e.g. diagrid system, cross-laminated timber (CLT) panels) have been analysed. Local strengthening interventions applied to structural members has been reviewed by building typology focusing on RC, masonry, steel, precast, and timber buildings. Retrofit interventions for non-structural elements has been also investigated, as their damage represents a high percentage of losses in terms of cost, injuries, and functionality in case of a seismic event (Filiatrault and Sullivan 2014). The identified technologies have been classified both qualitatively by means of selected Life Cycle Thinking (LCT) criteria (e.g. holistic/integrated compatibility, occupants’ disruption), and quantitatively through a cost analysis carried out by means of a two-phase approach. The first phase regards the detailed study of 26 seismic retrofit projects related to residential and non-residential masonry and RC buildings in northern Italy to analyse the corresponding cost breakdown of all retrofit activities, namely construction site management, structural interventions, technical expenses, and energy upgrading (when foreseen). Structural intervention cost resulted equal to 40% and 48% of the total cost of all retrofit activities in masonry and RC buildings, respectively. This analysis has led to the creation of a cost inventory used in the second phase of the quantitative analysis to estimate the average cost range of selected seismic retrofit measures for masonry and RC buildings. This inventory should serve as supporting tool in the preliminary phase of the retrofit design to facilitate the stakeholders’ initial decisional process.

Energy retrofit technologies (ERTs), compatible with seismic retrofit technologies, have been classified by their application to the components of building envelope: (i) walls (insulation technologies, ventilated façades, green walls), (ii) floors and roofs (insulation technologies, green and cool roofs), (iii) windows (replacement, and weather-stripping), and (iv) doors (replacement, films, weather-stripping). The identified ERTs have been classified according to a set of indicators, e.g. unitary cost of implementation, unitary energy saved, unitary cost-effectivity, disruption time, life span and generated waste. Selected ERTs have been ranked based on their attractiveness for potential investments to implement seismic and energy retrofit of buildings in EU countries with moderate-to-high seismic hazard (according to the ESHM13). A multi-criteria decision analysis has been carried out through the Analytic Hierarchy Process (Saaty, 1980). Insulation of wall air chambers and internal insulation of roofs result in highly attractive EETs for investment. Replacement of doors/windows and prefabricated units for external wall insulation or external thermal insulation composite systems reveal medium and low rank of attractiveness, respectively.

3.2 Combined Seismic and Energy Retrofit Technologies for Existing Buildings

The combined and integrated seismic and energy retrofit technologies currently represent a forefront research field. However, this topic is quite new, thus requiring further development to extend the range of effective intervention options. A review based on the most recent studies available in the scientific literature has led to the identification of three main categories of potential valuable integrated solutions.

The first category refers to integrated exoskeleton solutions, which include shell-grid solutions, ranging from simple steel braces combined with solar shading to material-efficient steel diagrids integrated with various thermal panels (Labò et al. 2020). Other examples refer to shell-exoskeletons, e.g. using insulated RC walls (Pertile et al. 2021) or RC frames combined with thermal insulation panels or new masonry infills (Manfredi and Masi 2018).

The second category concerns integrated and combined interventions on the building envelope encompassing solutions aimed at strengthening and insulating the existing envelope. A few solutions refer to textile reinforced mortars (TRM) combined with thermal insulation (Bournas 2018), integrated prefabricated panels, and engineered timber, such as CLT panels (Margani et al. 2018).

The third category regards interventions on horizontal elements, namely roof and floor, of masonry buildings. A couple of examples in this direction refer to the so-called Nested Building, (Valluzzi et al. 2021), and strengthened roofs with a ventilation layer (Giuriani et al. 2016).

A comparison of the main advantages and criticalities in terms of cost, invasiveness, disruption time is briefly presented for each category of integrated interventions. Both exoskeleton solutions and interventions on the building envelope exhibit the important benefit to be applied from the outside, thus reducing the occupants’ disruption. Conversely, the interventions on horizontal elements result rather disruptive, thus it is preferable to employ them in case of a full building renovation and in combination with interventions on existing masonry walls. However, exoskeletons suffer from high cost and considerable environmental impacts compared to the envelope interventions, which typically result cost-effective (Pohoryles et al. 2020) and environmental-friendly as in the case of CLT panels. As a distinctive advantage, exoskeleton solutions can lead to an architectural renovation of an existing building, beyond high enhancing seismic performance and supporting a number of different energy efficiency technologies. Examples of integrated exoskeleton solutions are exemplified in case studies 1 and 3 presented in the paragraph 3.4.

3.3 A Simplified Assessment Method for the Combined Upgrading of Existing Buildings

The development of assessment methods for the combined seismic and energy retrofit of existing buildings is a priority issue considering that currently single-performance (e.g. seismic or energy) retrofit strategies are still the most common approaches of building renovation, potentially leading to unsustainable solutions over time. This stream of procedures refers to sector-specific methods, which include two main categories of assessment methods, namely (i) seismic loss assessment methods, and (ii) conventional LCA and Life Cycle Energy Assessment (LCEA) methodologies. They aim to assess respectively either the seismic or the environmental and energy performances of an existing building before and after the retrofit.

The need of a radical change of direction by considering a building as a multi-performance whole with different potential deficiencies is still underlined by recent studies (e.g. Passoni et al. 2021) aimed at emphasizing the importance of an integrated life cycle-based retrofit in the perspective of a sustainable and resilient built environment. Hence, a second steam of procedures has been developed in the last decades referring to multi-performance assessment methods and tools, which include qualitative and quantitative integrated methods. The former category, whose roots date back to 1990’s, concerns EU and non-EU sustainability rating systems based on indicators of different weight. The latter category includes methods to combine different life-cycle performance metrics of a building (Menna et al. 2022) with the SSD methodology resulting particularly noteworthy.

The review of these assessment methods underlines that sustainability rating systems are mostly developed for new buildings. These tools include energy efficiency and CO2 emission indicators as highly relevant, but a seismic safety indicator is implemented in a couple of them with a low weight. Hence, quantitative integrated methods need to be considered for a proper combined seismic and energy retrofit assessment of existing buildings. However, the complexity of integrating many different input data draws the attention to the need of developing a simplified method for the combined retrofit assessment considering the SSD methodology relevant to achieve this goal.

The framework of the proposed simplified combined assessment method consists of the following four interconnected steps:

  1. 1.

    Input information, aimed at collecting the initial data and boundary conditions of an existing building needing retrofit.

  2. 2.

    Selection of techniques, aimed at analysing the physical and mechanical characteristics of the seismic and energy retrofit technologies to identify a set of potential compatible measures.

  3. 3.

    Integrated retrofit design and evaluation, representing the computational step for the assessment of the seismic, energy, and environmental performances of the combined retrofit in a life cycle perspective by achieving a single result in economic terms.

  4. 4.

    Optimised solutions, dealing with a comparative assessment of different combined retrofit solutions to identify the most effective one.

Attention is drawn on the third step of the proposed method to provide further details, since it represents the computational core considering the SSD methodology as point of reference for its development. Indeed, this step aims to assess the seismic, energy, and environmental performances of the retrofitted building, converted into equivalent costs and subsequently combined to obtain a global monetary result.

Each of the three performance components is assessed at three different stages of the building life cycle, i.e. initial time (time of the retrofit intervention), extended lifetime, and end of life, leading to three total cost contributions. The total initial cost (€/m2) is the sum of the equivalent costs of seismic and energy retrofit interventions, and the equivalent CO2 costs for manufacturing the retrofit materials. As for the extended lifetime stage, the three performances are assessed on an annual basis, expressed in economic terms and combined into a global Integrated Retrofitting Performance Parameter (IRPP) (€/m2year). The IRPP is defined as the sum of expected annual seismic losses, expected annual costs related to energy consumption, and equivalent CO2 costs due to seismic damage and energy consumption. The difference in IRPP before and after the retrofit (ΔIRPP) represents the total extended lifetime cost, which includes the economic savings due to retrofit. The total end-of-life cost (€/m2) is the sum of the equivalent cost for dismantling seismic and energy retrofit measures, the cost associated with the environmental impact of dismantling, minus potential benefits due to recycle/reuse.

The final result of the equivalent economic performance, obtained by summing up the three total cost components above, expresses the variation of the total life cycle cost over the lifetime of the building, and it can be represented by a cost vs time curve. This curve shows the initial costs for the combined interventions, the recovery of the investment over time up to the payback time, and the potential credits achievable at the end of life stage due to the recycle/reuse of materials/components.

3.4 Application of Standard and Simplified Combined Assessment Methods to Case Studies

Four case studies of representative buildings are identified to apply both the selected standard (i.e. SSD methodology) and the proposed simplified combined assessment methods. A detailed analysis of the most common EU structural systems, and vertical and horizontal elements of building envelope is first carried out. Subsequently, a six column seismic-climatic hazard matrix to identify potential locations of case studies is developed by combining two macro-seismic hazard areas (based on the average values of PGA available from ESHM13) with three climatic zones (based on 2017 Eurostat HDD data). Four representative buildings for combined retrofit are selected in Italy, as this country includes all possible scenarios of the matrix.

Case study 1 is a residential RC building in Toscolano Maderno, retrofitted with steel exoskeletons, external expanded polystyrene cladding, and heating system replacement. Case study 2 is a residential brick masonry building in Dalmine, retrofitted with prefabricated steel shear walls, and the application of roof insulation, new heating system and windows. Case study 3 is the “Santini” RC primary school in Loro Piceno, retrofitted with an exoskeleton of concentric steel x-braced frames and a double-skin envelope. Case study 4 is a rubble masonry building hosting the city hall of Barisciano. Various local strengthening interventions and the replacement of the heating system and windows were considered.

The four steps of the SSD methodology are applied to the four case studies considering both the ‘as-built’ and retrofitted building scenarios. Seismic and energy retrofit interventions have provided an effective combined improvement in all case studies, easily demonstrated by comparing the monetary global assessment parameter accounting for the combination of the energy, structural, and environmental costs before and after the retrofit. Indeed, total cost reductions (compared to as-built building scenarios) equal to approximately 65%, 43%, 60%, and 25% result for the case studies 1, 2, 3, and 4, respectively.

The proposed simplified combined assessment method is also applied to the four case studies to demonstrate the advantages of implementing a user-friendly assessment tool that can be easily used by practitioners without requiring complex calculations. The focus is devoted to the third step of the method, i.e. the computational step, leading to the creation of the life cycle curves expressing the final economic result for the four case studies. Specifically, the estimation of the three total cost contributions corresponding to the initial time, the extended lifetime, and end-of-life is carried out.

Attention is drawn to the extended lifetime stage devoted to the assessment of the IPRR before and after the retrofit, i.e. ΔIRPP. The simplicity of the method in calculating the expected annual seismic losses and costs related to energy consumption is ensured by using generalised seismic (i.e. fragility curve) and energy (i.e. thermal energy demand vs HDD curve) performance results. These are based on simulation procedures (i.e. nonlinear static and energy dynamic analyses) for the combination of different representative building classes and retrofit techniques. The calculation of ΔIRPP, for the four case studies, confirmed the economic savings due to retrofit. Furthermore, the payback time for the four case studies, considering a service life of 50 years, resulted in 18, 23, 19, and 22 years, respectively. These results can be reduced, if fiscal incentives are considered (e.g. “Ecobonus” and “Sismabonus” in Italy).

Further research is needed to enrich the catalogue of generalised seismic and energy performance curves and extend the application of the simplified method to a larger number of representative building classes in Europe.

3.5 Priority Regions

Regional assessment and prioritisation is carried out by means of an integrated analysis based on specific metrics addressing three assessment routes, i.e. (i) seismic risk to buildings and occupants, (ii) energy performance of buildings, and (iii) socioeconomic indicators, using as a reference a common exposure model. The latter consists of a recent seismic exposure model adopted as a starting point (Crowley et al. 2021), and subsequently extended to address structural and energy attributes of the EU building stock. Data and models related to seismic hazard (Danciu et al. 2021), climatic (Eurostat 2022), physical (Crowley et al. 2021) and social (e.g. Annoni and Bolsi 2020) vulnerability, and energy performance modelling have been employed.

The metrics from each assessment route have been used to form indicators and subsequently explore their impact on regional prioritisation. Regional assessments are performed both independently and in an integrated way.

Absolute average annual loss rankings in terms of economic loss and loss of life prioritise European regions of moderate-to-high seismicity and vulnerability with regions of Italy governing the top 100 rankings, followed by regions of Greece or Romania. However, normalising loss to the number and value of buildings or number of occupants, places Romanian and Greek regions on top of Italian ones.

Absolute average annual loss rankings in terms of energy consumption highlight densely built and populated regions, extending from Spain and France to Austria and Hungary, and towards northern countries. However, normalising energy consumption to the number of buildings and climatic conditions, shifts priority from northern to central and southern Europe, mainly Italy, Germany and France.

Prioritisation based on socioeconomic indicators shifts the focus to southern and eastern European regions, similarly to the trends of seismic risk.

Integrated indicators in terms of pure economic loss terms have been first assessed, resulting in a high priority of seismic regions in Romania, Greece, Italy, Slovenia, Croatia, and Bulgaria. Integrating additionally socioeconomic vulnerability, shifts priority to south-eastern Europe. These rankings can be used to achieve a focussed approach in local, regional or European building renovation planning.

4 More to Come, the New European Bauhaus Initiative

4.1 The Legacy of the (Original) Bauhaus

Everybody has heard about the experience of the Bauhaus. Even though some find in the experience of the Bauhaus the seeds of the extreme outcomes of the Rationalism, and the ways the Bauhaus navigated the stormy seas of the ideologies at those times are often the object of debates, there are no doubts that the Bauhaus left a profound legacy in terms of the way we conceive and design our buildings, and much more. In broader terms, the Bauhaus experience has affected the way we learn, design, produce and live in our buildings. It underpinned the industrial mass production and it is seen as the kickoff of industrial design, following the motto “form follows function”.

In the following, quoting related to the main peculiarities of the original Bauhaus is made from the (Britannica website).

Bauhaus, in full Staatliches Bauhaus, school of design, architecture and applied arts that existed in Germany from 1919 to 1933. The Bauhaus was founded by the architect Walter Gropius.

Bauhaus, or “house of building”, a name derived by inverting the German word Hausbau, “building of a house”.

Gropius’ “house of building” included the teaching of various crafts, which he saw as allied to architecture, the matrix of the arts. By training students equally in art and in technically expert craftsmanship, the Bauhaus sought to end the schism between the two. The workshops were generally taught by two people: an artist (called the Form Master), who emphasized theory, and a craftsman, who emphasized techniques and technical processes, The Bauhaus admitted women, who rarely had opportunities to pursue an art education in Germany.

The Bauhaus included among its faculty several outstanding artists of the 20th century. Bauhaus teaching methods and ideals were transmitted throughout the world by artists and students.

On the example of Gropius’ ideal, modern designers have since thought in terms of producing functional and aesthetically pleasing objects for mass society rather than individual items for a wealthy elite.

4.2 The European Green Deal and the New European Bauhaus

The European Green Deal (European Commission 2019) reset the European commitment to tackling climate and environmental-related challenges that is this generation’s defining task. The atmosphere is warming and the climate is changing with each passing year. One million of the eight million species on the planet are at risk of being lost. Forests and oceans are being polluted and destroyed. The European Green Deal is a response to these challenges. It is a new growth strategy that aims to transform the EU into a fair and prosperous society, with a modern, resource efficient and competitive economy where there are no net emissions of greenhouse gases in 2050 and where economic growth is decoupled from resource use. It also aims to protect, conserve and enhance the EU's natural capital, and protect the health and well-being of citizens from environment-related risks and impacts. At the same time, this transition must be just and inclusive. It must put people first, and pay attention to the regions, industries and workers who will face the greatest challenges. Since it will bring substantial change, active public participation and confidence in the transition is paramount if policies are to work and be accepted. A new pact is needed to bring together citizens in all their diversity, with national, regional, local authorities, civil society and industry working closely with the EU’s institutions and consultative bodies.

President von der Leyen in her 2020 State of the Union Address at the European Parliament Plenary has endorsed the Green Deal as the blueprint to make the environmental transformation. She pointed out that our buildings generate 40% of our emissions and need to become less wasteful, less expensive and more sustainable. However, she underlined that the mission of the European Green Deal involves much more than cutting emissions.

She stated that we need to change how we treat nature, how we produce and consume, live and work, eat and heat, travel and transport, to kickstart a European renovation wave and make the Union a leader in the circular economy. But this is not just an environmental or economic project: it needs to be a new cultural project for Europe. Every movement has its own look and feel. And we need to give our systemic change its own distinct aesthetic – to match style with sustainability.

This is why she launched a New European Bauhaus (NEB), a co-creation space where architects, artists, students, engineers, designers work together to make that happen.

4.3 A New European Bauhaus Taxonomy

The New European Bauhaus has been started as a co-creation initiative, and the Joint Research Centre has been charged, by means of a Preparatory Action to be conducted in collaboration with a group of European experts, with the duty of developing a labelling system and the associated taxonomy.

The final goal is to define a self-assessment tool to assess the performance of a project in (terms of) all its components related to the three core inseparable NEB values, i.e. sustainability, quality of experience, and inclusion, which might be used to monitor the design and implementation of individual NEB projects. We would like to co-develop a methodology for self-assessment based on the integration of the three NEB values to the multidisciplinary and collaborative approach. A number of indicators and their related assessment criteria will be identified to assist a proper identification and assessment of NEB projects.

The first action is to identify and classify those requirements and all the existing standards, guidelines and codes of practices related to each requirement to consequently identify gaps and further needs.

Finally, a specific New European Bauhaus taxonomy will be defined, to assess whether, and to which extent, a project complies with the three NEB dimensions (sustainability, quality of experience, and inclusion), and whether it follows a collaborative approach.

This is expected to have a profound impact on the way we address the challenge of the integrated seismic strengthening and environmental upgrading of existing buildings.