Integrated sustainability assessment of construction waste-based shading devices for the refurbishment of obsolete educational public building stock

Journal of Building Engineering 87 (2024) 109024 Available online 19 March 2024 2352-7102/© 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Integrated sustainability assessment of construction waste-based shading devices for the refurbishment of obsolete educational public building stock Torsten Masseck, Oriol París-Viviana, Saeid Habibi , Oriol Pons-Valladares * Department of Architectural Technology, Universitat Polit` ecnica de Catalunya (UPC), Diagonal Avenue 649, 08028, Barcelona, Spain ARTICLE INFO Keywords: Circular economy Life cycle assessment Life cycle cost Energy performance Facades ABSTRACT Buildings and the construction sector are responsible for a considerable share of human environmental impacts, and have high economic and social costs. This project aims to contribute to advancing towards circular economy-based construction techniques, to improve the sector’s sustainability performance. Specifically, the project developed a tool to assess the sustainability of waste-based shading devices for public school building stock. The tool combines a multi-criteria decision-making method with the Delphi interview technique to reduce possible biases to a minimum. It is a flexible instrument for holistic sustainability assessment of initial designs. The tool was validated by assessing six initial designs created in three cross-disciplinary university courses. The resulting high economic satisfaction indexes – up to 0.93 on a 0 to 1 scale – and low sustainability indexes – from 0.39 to 0.53 – confirm that four alternatives are economically feasible. However, the environmental and social parameters could be improved. In this first application of the tool, the comparison of recycled and reused construction materials versus new building materials allowed informed trade-offs to be made between the associated embodied and operational carbon, to compare the long-term operational energy and carbon savings of the higher-performing solution with new materials versus the upfront lower embodied carbon of sourcing and applying reused and recycled materials for similar alternatives. Findings on the contribution of reusing materials, with reductions in environmental impacts up to 45%, prove that this project is contributing to defining more sustainable facades. List of symbols A Response value X min (indicator’s abscissa), generally A =0 a Life cycle cost (LCC) coefficient, general location of the building site B Factor keeping the function within (0.00, 1.00) b1 LCC coefficient, access difficulty to the building site b2 LCC coefficient, storage capacity of the building site b3 LCC coefficient, material transport to the building site b4 LCC coefficient, building work economic potential b5 LCC coefficient, occupants’ presence in a rehabilitation building site * Corresponding author. E-mail address: [email protected] (O. Pons-Valladares). Contents lists available at ScienceDirect Journal of Building Engineering journal homepage: www.elsevier.com/locate/jobe https://doi.org/10.1016/j.jobe.2024.109024 Received 22 December 2023; Received in revised form 23 February 2024; Accepted 9 March 2024 Journal of Building Engineering 87 (2024) 109024 2 C i Inflection point factor K i Factor determining the response value to Ci P i Shape factor defining a concave, convex, linear, S-shaped curve S min Minimum satisfaction S max Maximum satisfaction V i Dimensionless satisfaction of the assessed indicator X i Indicator abscissa that generates V i value X min Indicator minimum value corresponding to non-dimensional value 0 or 1 depending on the function tendency X max indicators maximum value corresponding to non-dimensional value 0 or 1 Abbreviations ANP Analytic network process CDW Construction and demolition waste DCcv Decreasing concave DCvx Decreasing convex DIY Do it yourself EoL End of life EU European Union GHG Greenhouse gas HVAC Heating, ventilation and air conditioning ICcv Increasing concave ICvx Increasing convex IEQ Indoor environmental quality IS Increasing S-shaped LCA Life cycle assessment LCC Life cycle cost MCDM Multi-criteria decision-making method MIVES Modelo Integrado de Valor para una Evaluaci´ on Sostenible (integrated value model for sustainability assessment) PVC Polyvinyl chloride RC Reinforced concrete SLCA Social life cycle analysis 1. Introduction The construction sector and building stock have been highly negative contributors to the main environmental indicators, such as global energy consumption and CO 2 emissions, with shares quantified from 30 to 40% for decades [1,2]. Consequently, there have been governmental and non-governmental initiatives to decrease this environmental impact. For instance, the European Union (EU) has developed regulations and directives to achieve the EU 2050 climate neutrality target by reducing the aforementioned environmental impacts caused by buildings [3,4]. This situation can be explained by the obsolete linear economic model that the construction sector has been following [5]. Though it has been clear for decades that solutions should involve a circular economy approach, which can close the loop and reuse discarded materials and buildings, this is still to be implemented in the construction sector and its practices [6]. It is crucial to implement circularity in the rehabilitation of buildings, where most investments are made in relation to improving energy efficiency [7]. In Europe, there are over 220 million buildings, of which 85% were built more than 22 years ago and are high-energy consumers [8]. Consequently, rehabilitations since 2020 are required to reuse or recycle 70% or more of the construction and demolition waste (CDW), to reduce the impact of these rehabilitation processes significantly. In this case, fewer new materials are needed and waste is recirculated [9]. In Spain, over half of the building stock was constructed before 1980 and statistics estimate that over one million buildings are in a deficient state of conservation [10]. Therefore, rehabilitation of existing building stock is essential to mitigate the aforementioned high environmental impact. When this stock is assessed in terms of sustainability – including environmental, economic and social performance – it is highly efficient to determine archetypical reference buildings using clustering techniques [11]. The reference buildings can be evaluated in detail and their performance outputs easily scaled up to the total stock that they represent. In Spain, the building stock of schools has endemic deficiencies, with problems regarding indoor light and ventilation quality, user comfort and fulfilment [12]. Educational buildings can work as third teachers, for instance by raising users’ awareness of existing deficiencies. Users can participate in rehabilitation processes, for example by giving feedback about comfort or contributing to the selection of improvement options [13]. Buildings facades are one of the largest and main components, since these vertical envelopes contribute greatly to the sustainability performance achieved by the entire building. Numerous previous studies confirm facades’ predominant role in minimizing environmental effects, decreasing buildings’ costs and providing comfort to inhabitants [14]. Notably, between 25% and 40% of the total construction cost is related to building envelopes and up to 60% of heat losses of building skins occur via facades [15]. Facade T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 3 functions include the protection of interior spaces against adverse environmental influences like pollution, wind, rain and humidity. Through optimized thermal performance, facades can reduce heating, ventilation and air conditioning (HVAC) loads and lighting loads, among others [16]. Furthermore, facades are key elements for passive energy renovations, to achieve free-running buildings [17]. Facade renovations can increase indoor environmental quality (IEQ) without an increment in energy expenditure, due to passive or bioclimatic features. Generally, free-running buildings allow users to directly control the passive systems so that the buildings perform better in terms of air quality and energy performance, among other advantages. Former studies estimate that optimized orientation and shading devices can lead to 32–47% cooling load reductions and 13–56% of primary energy savings in Mediterranean climates [18]. Regarding rehabilitation processes, facades consist of numerous layers from inside to outside [19]. Rehabilitation focused on the outer layers cause less disruption to interior spaces and occupants’ activities. Former studies and projects conclude that new facade solutions should be dynamic to adapt their energy performance and technical configuration to seasonal and climate change [20]. These solutions should furthermore allow optimization of the energy balance of buildings through the control of thermal energy, light energy and radiation. Other crucial issues are that active building systems, if applicable, should work alongside passive systems to achieve better sustainability performance. This implies proper building management during the building usage phase. Building management must consider differences in users’ comfort requirements and perceptions, as these depend on age and gender, among other factors, and require a holistic user-focused comfort study. Finally, facades play an important role in urban landscape and in cities’ image due to their high visibility in the urban space. Building skins therefore influence the character of a city’s neighborhoods and even have the potential to positively influence social attitudes [21]. In all building skin areas, openings are essential to provide daylight and views, while their solar thermal gains and thermal conductivity highly influence the entire building’s energy efficiency and interior comfort. Through the use of adequate solar control devices, glare and direct thermal gains can be controlled. This makes a major contribution to users’ wellbeing, and enables activities to develop suitably inside the building [22]. There are many potential refurbishment solutions that are focused on facades. These range from passive solutions (such as green envelopes and solar control devices) to smart facades (for example, photovoltaics that produce electricity or titanium dioxide that absorbs pollution). Passive-smart hybrid facades are a mixture of these [23]. Living facades can contribute to enhancing biodiversity and ecosystems in urban sites, while smart facades can save up to 80% of buildings’ energy consumption and reduce up to 20–30% of related greenhouse emissions [18,24]. At the same time, in complex facades, mechanical and electrical systems might generate up to 40% higher investment costs, which are often incompatible with the available resources for building stock refurbishments. These figures illustrate the potential of low-cost smart facades, for example building skins within the circular economy concept [25]. Life cycle assessment (LCA) shows that facades account for 30–40% of the total environmental impact of new construction. In envelope rehabilitation, this impact could represent around 60% of the intervention, depending on the type of building [26]. Through the incorporation of recycled or reused materials, the impact of facades could be reduced significantly because of a lower demand for new materials and the reintroduction of waste into the construction process. Therefore, recycling implies a second production processing cycle, which usually results in new industrialized products. In this context, the study aimed to develop a specific method to assess innovative facade solutions to improve schools’ interior comfort. As depicted in Table 1, several former studies have developed models to assess sustainability indicators of facades. The model developed in this research project was designed to solve the aforementioned problems of school shading from a holistic sustainability perspective. Multiple tools were used to achieve flexibility and precision, while the particularities of the research project were considered. The model was applied for the first time to assess initial designs developed by students for the reference building. The rest of the article explains the methodology in Section 2, presents the case study and the alternatives in Section 3, shows the results in Section 4, discusses these results in Section 5 and concludes about the main findings and future works in Section 6. 2. Methodology This project followed the workflow depicted in Fig. 1 to achieve the aforementioned objectives. In the first step, the initial designs were defined. These were then assessed during the third step, using a new assessment tool developed in the second step. All steps focused on the aforementioned context from the perspective of the educational department, municipality and school professionals who make the decisions on refurbishment of school facades in the cluster [12]. Firstly, students and professors from three university courses defined the initial designs [33,34], following challenge-based and service-centered learning methods [33]. Three professors and 76 students participated in these courses, entitled LOW3: Living Zero!, Materiality and Project, and Building Technologies and Materials Table 1 Main former models developed to assess sustainability criteria of facades and shadings. Year Building Element Scope Methods Ref. 2023 Office Smart shading Sustainability PROMETHEE II and Energy Plus [27] 2022 Commercial Facade Sustainability ANP [28] 2022 Housing Facade Sustainability MIVES and AHP [19] 2022 Multi-story Facade materials Energy, costs, fire, construction VIKOR [29] 2020 Schools Smart facades Sustainability MIVES and Delphi [20] 2020 Office Windows and shading Energy consumption and thermal comfort Design Builder jEplus +EA [30] 2020 Multi-story Shading Thermal comfort and daylight control Rhinoceros, Grasshopper, Ladybug and Honeybee [31] 2018 Schools DIY shading Sustainability MIVES and AHP [32] Legend: ANP is analytic network process; DIY is do it yourself; MIVES is “Modelo Integrado de Valor para una Evaluaci´ on Sostenible” (integrated value model for sustainability assessment); Ref. is Reference; Sustainability includes economic, environmental, social and technical indicators. T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 4 with Low Environmental Impact. Participants were from three schools of the Universitat Polit` ecnica de Catalunya - BarcelonaTech. During one semester, the LOW3: Living Zero! and Materiality and Project courses defined six initial designs, while the third course had a consultancy role, for the design teams to rely on. The initial designs followed an 11-point rubric, which is described in depth in Appendix A. Briefly, the points are: 1) low-cost solution that follows the circular economy concept by incorporating construction and demolition waste and end of life (EoL) materials that return to the production cycle, 2) solves deficiencies in facade solar control, 3) modulates light inputs according to occupants’ needs, 4) maintains its integrity and presents limited deformations due to external loads, transmitting load to the existing building adequately, 5) constitutes a hybrid system that combines active and passive elements regarding the generation, storage or management of energy, water, vegetation, air purification or similar, 6) integrates well into the existing architecture and reflects social, cultural and aesthetic values: it is sensitive to the educational community and improves the image of the school, 7) improves the thermal and acoustic behavior of the building, 8) is innovative, 9) meets the required durability needs, 10) behaves well in response to fire and complies with corresponding regulations, and 11) its prototypes can be fabricated in university campus workshops. The second step defined a sustainability assessment tool that combines MIVES and Delphi. MIVES is a multi-criteria decisionmaking method (MCDM) called the integrated value model for sustainability assessment (in Spanish, the Modelo Integrado de Valor para una Evaluaci´ on Sostenible [MIVES]) [35]. Delphi is a technique for structured projects that guides researchers to rigorously prepare questionnaires for experts to obtain results with high reliability [36]. The project selected this combination of methods because the solution to this multi-criteria problem required a MCDM that: 1) could be adjusted to the specific topic and problem presented in the previous section of waste-based shading devices to improve educational building stock; 2) has successfully been applied to similar case studies [14,19,20,37]; and 3) is able to provide a flexible assessment [38]. The new tool is based on the aforementioned sustainability assessment tools for facades that were previously developed [39]. Nevertheless, the tool differs from former experiences because: a) it considers the particularities of the reference building of the studied educational building stock, Fig. 1. Steps followed, participants involved, and methods and tools used in this research project. Legend: CBL is challenge-based learning; MCDM is multi-criteria decision-making method; MIVES is “Modelo Integrado de Valor para una Evaluaci´ on Sostenible” (integrated value model for sustainability assessment); LCC is life cycle cost; and LCA is life cycle assessment. Table 2 Decision tree with its requirements, criteria, indicators and weights. R# Requirements C# Criteria I# Indicators R1 Economic (simplified LCC) (29%) C1 Cost (100%) I1 Materials & production cost (40%) I2 Annual maintenance & operation cost (40%) I3 Dismantling cost (20%) R2 Environmental (simplified LCA) (39%) C2 Fabrication & assembly (30%) I4 Energy consumption (48%) I5 Embodied carbon (52%) C3 Use (49%) I6 Annual energy saving (44%) I7 Energy conversion efficiency (28%) I8 Annual blocked emissions (28%) C4 End of life (21%) I9 Recyclability (49%) I10 Reusability (51%) R3 Social (32%) C5 Design & production & assembly added value (29%) I11 Design innovation (31%) I12 Fabrication & ease of assembly (30%) I13 Flexibility & multi-functionality (39%) C6 User comfort (45%) I14 Ventilation performance (36%) I15 Light & visual performance (35%) I16 Acoustic performance (29%) C7 User added value (26%) I17 User safety added value (66%) I18 User interaction & feedback (34%) T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 5 relying on a previous doctoral dissertation [40]; and b) it can be used iteratively to optimize the alternatives that are assessed. Section 2.1 explains the tool development in depth, as it is the main part of this research project’s methodology. The third step involved the sustainability assessment of the initial designs. This step allowed determination of the global sustainability indexes and partial results of the solutions, and validated the tool by applying it for the first time. 2.1. Tool definition based on MIVES and Delphi This section includes the definition of the decision tree and the weights and value functions of its components. Table 2 presents the decision tree, which was defined based on previous studies [19,29,39] and the characteristics and boundaries of this specific project, as mentioned in the introduction. The tree weights were defined by an external experts’ panel, following the Delphi technique. This decision tree includes the three commonly accepted pillars of sustainability [39], seven criteria and 18 indicators. Table 3 explains the indicators that, following MIVES, are the most discriminative for the specific case study and have no overlap between them, to guarantee the assessment’s agility and rigor. For example, thermal performance is not an independent indicator like ventilation, light or acoustic performance, as it is included in I6, I7 and I8. These indicator values are obtained following different methods. I1 and I3 are calculated using a simplified life cycle cost (LCC) analysis based on BEDEC [41] database values from 2023 and the recommended weighing values presented in Appendix B. Direct cost data from the local database BEDEC have costs that are slightly higher than market costs, for which availability cannot be ensured. Moreover, transport and management are not considered in market costs. I4-5 and I9-10 calculations follow a simplified life cycle assessment (LCA), based on BEDEC [41] with environmental impact values using the SimaPro v9.1.1 [49] and Ecoinvent v3.6 [50] database, in accordance with ISO 14040 [51], ISO 14044 [52] and UNE EN 15804 [53]. The scope of the study includes the product and construction stages and end of life stages of the LCA [54]. The use of simplified LCC and LCA allows a flexible, rigorous assessment of cost and environmental indicators, as proven in numerous former MIVES tools [39,55]. The BEDEC database provides local data on cost and environmental indicators and has been successfully used in similar methods [56]. I2 gives points to the inspection and maintenance works that the materials require according to the facade orientation, a local database [42] and previous studies [19,57, 58]. It also considers the amount of materials in the facade, according to the aforementioned LCC in I1 and I3. The scope of the study includes LCA phases A1-5 (product and construction stage) and C1-4 (end of life stage). I6–I8 are calculated by applying consumption prediction methods using the software tool Design Builder. The simplified version of the shading alternatives are added using the default louvre option, as presented in Appendix C. The use of Design Builder is supported by previous related research projects and allowed the use of previous models of reference school buildings in need of rehabilitation within the Barcelona Metropolitan Area [11]. Annual blocked carbon emissions (I8) assesses the shading device’s contribution to the reduction or sequestration of emissions during the usage phase by calculating the amount of a) avoided energy consumption, b) generated energy and/or c) absorbed emissions (see Appendix B). I11-18 are assessed by assigning points based on the previous technical literature depicted in Table 3 and Appendix B. The external experts’ panel was chosen following the Delphi strategic and unbiased method to qualify the expertise of each panel member. Following previous studies, the authors defined specific requirements that the experts should meet, according to the project boundaries. A list of candidates was drawn up that included academic specialists, architectural offices, construction industry professionals, engineering firms, teaching teams and public administration representatives. The panelists that were chosen met at least four of the requirements listed in Appendix D and scored at least eight points on the relative point system that was specifically developed for this project and presented in Appendix E, as suggested by Delphi [59]. Furthermore, to decrease bias to its lowest level, this project applied the specific measures shown in Appendix F and used a modified version of the nominal group technique [60] to Table 3 Indicator description. # Description and quantification of the indicator Ref. I1 Measures of the fabrication and assembly cost of the system based on a local database [41] I2 Inspection and maintenance works, disregarding energy that can be saved or generated by facade, annually and based on a local database [42] I3 Deconstruction and demolition costs based on a local database [41] I4 Energy required to fabricate and assemble each layer (extraction phase to installation phase) I5 CO 2 emissions during fabrication and assembling phase (extraction phase to installation phase) I6 Annual operational energy savings of the building [18] I7 Ratio between useful output and input energy during the usage phase I8 Shading device contribution to the reduction or sequestration of emissions I9 Recyclable rate based on a local database [41] I10 Reusable rate based on a local database I11 Novelty of the design. Related patents, articles and studies [43] I12 Simplicity to produce and set up [44] I13 Flexibility of the proposal to adapt to different cases and capacity to solve multiple functions, multi-performance [20] I14 Placements and movements for each layer’s components to transfer and direct the wind direction to inside a room to provide fresh air and natural ventilation as a double skin facade [45] I15 Solar control, light optimization, visual comfort, exterior view and glare protection control, color rendering of objects inside the classroom, aesthetics (harmony, etc.), aspect and visual quality. [46] I16 Capacity to avoid nuisance to users from vibrating and noise production. Absorption capacity of exterior noises [47] I17 Positive behavior in terms of fire resistance and other possible risks beyond the standard; in points (excluded durability already in I2, and wind already in I16) [48] I18 Capacity to interact and give feedback to users; in points [13] T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 6 collect and consider experts’ feedback [20]. Appendix G shows the 15 chosen experts’ main qualifications. This study required two rounds of surveys that are presented in Appendix H. Value functions are a crucial element of MIVES-based tools that permit unification of the units of all indicators to a dimensionless scale to integrate the results, considering the decision tree and weights [61]. The definition of value functions has four main phases [57]: i) establishing the function’s increasing or decreasing tendency; ii) defining the X min and X max , which are the indicators’ maximum and minimum values corresponding to non-dimensional values 0 and 1 or vice versa depending on the function tendency; iii) determining the function shape such as concave, convex, linear or S-shaped; and iv) establishing the value function equations. The first three phases considered the defined decision-maker for this tool and relied on technical-related literature and documents, previous-related projects, the experts’ panel and the authors’ knowledge and expertise. The mathematical expressions of the value functions are Equations (1) and (2) [62]. Vi=A+B.⎡ ⎣1−e −ki•[|Xi−Xmin | Ci]Pi ⎤ ⎦(1) B=[1−e −ki•[|Xmax −Xmin | Ci ]Pi ]−1 (2) Legend: V i =dimensionless fulfilment of the assessed indicator; X i =indicator abscissa that generates V i value; A =response value X min (indicator’s abscissa), generally A =0; P i =shape factor defining a concave, convex, linear, S-shaped curve; C i =inflection point factor; K i =factor determining the response value to Ci; X min =corresponding point to minimum fulfilment (S min =0); X max =corresponding point to maximum fulfilment (S max =1); B =factor keeping the function within (0.00, 1.00), obtained by Equation (2). Table 4 presents the shape and parameters of the 18 indicators’ value functions. Considering the previously explained context and decision-makers, indicators I1, I4 and I5 have linear functions because their fulfilment is indirectly proportional to their values. I2 has a decreasing concave (DCcv) function because the tendency is decreasing and it is a crucial indicator for which high contributions are required. I12 to I17 have increasing concave (ICcv) function shapes because they are also crucial indicators but with an increasing tendency. In contrast, I7, I9–I11 and I18 have increasing convex (ICvx) functions because they are indicators with an increasing tendency that need to be promoted by positively evaluating all the small contributions. These are similar to the I3 decreasing convex (DCvx) functions, although these have a decreasing tendency. I6 and I8 have increasing S-shaped (IS) functions because values below 0 give zero fulfilment and values greater than zero need to be promoted. 3. Case study This tool was first applied to study designs to improve Bellvitge School. This is an elementary educational center located in a medium built-up density area with narrow canyon streets in the Barcelona Metropolitan Area. This building is the real-reference school building in the cluster BCN.C1 [11], which was selected as the closest to the cluster centroid. Its validity was checked against the annual energy consumption for Barcelona. This building was chosen to be able to upscale the results to the cluster, which has a Mediterranean climate [66]. The climate has slightly cold winters and hot summers, thus it requires more heating than cooling, with 1419 and 588◦days respectively to reach 18 ◦C [40]. The building was constructed in 1972 with an H-shaped floor plan that defines Table 4 Parameters of the indicators’ value functions. I# Indicators UNIT Shape X max X min C K P Ref. I1 Materials & production cost € /m 2 DL 400 150 300 0.01 1 [41,55] I2 Annual maintenance & operation cost Points DCcv 200 25 100 0.02 2 [63,64] I3 Dismantling cost € /m 2 DCvx 300 100 200 0.01 0.5 [41,65] I4 Energy (extraction to installation) KWh/m 2 DL 200 50 125 0.01 1 [20,41] I5 Embodied carbon kgCO 2 e/m 2 DCvx 50 10 30 0.01 0.5 I6 Annual energy saving KWh/m 2 IS 100 −150 100 0.05 6 [20] I7 Energy conversion efficiency Percentage ICvx 100 0 1 0.05 0.8 I8 Annual blocked emissions kgCO 2 e/m 2 /a IS 0.03 −5⋅10 −4 2⋅10 −3 0.05 2 [20,58] I9 Recyclability Percentage ICvx 100 0 50 0.05 0.5 [20,41] I10 Reusability Percentage ICvx 100 0 50 0.05 0.5 [20,41] I11 Design innovation Points ICvx 100 0 50 0.05 0.5 [43] I12 Fabrication & ease of assembly Points ICcv 100 0 50 0.05 1.5 [44] I13 Flexibility & multifunctionality Points ICcv 100 0 50 0.05 1.5 [20] I14 Ventilation performance Points ICcv 100 0 50 0.05 1.5 [45] I15 Light & visual performance Points ICcv 100 0 50 0.05 1.5 [46] I16 Acoustic performance Points ICcv 100 0 50 0.05 1.5 [47] I17 User safety added value Points ICcv 100 0 50 0.05 1.5 [48] I18 User interaction & feedback Points ICvx 100 0 50 0.05 0.5 [13] Legend: DCcv is decreasing concavely; DCvx is decreasing convexly; DL is decreasing lineally; ICvx is increasing convexly; ICcv is increasing concavely, IS is increasing sshaped. T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 7 two-parallel blocks with three and four floors in the front and rear block, respectively. The front block is oriented southward to an open courtyard, while the rear block faces a multi-story residential building. This school has a capacity for 250 pupils from pre-school to primary education with 18 classrooms, four tutor rooms, a dining room, a library and office spaces. The building occupation is 176 school days per year, with a daily schedule from 9:00 to 16:30 h, a half hour break at 11:00 h and a lunch break from 12:30 to 15:00 h. There is an intensive period from the second week of June until the end of the summer term, with a schedule from 9:00 to 13:00 h. The heating systems are non-regulated water radiators served by centralized natural gas boilers from the second week of November to the first week of April. The building has fluorescent lighting with an average lighting power density of 8.6 W/m 2 . The equipment power density is 4.5 W/m 2 in classrooms and 10 W/m 2 in offices. This project focuses on the front block, which has 2045.53 m 2 of conditioned area and a floor to ceiling height of 2.8 m. The study specifically focused on the openings of the south facade that has a window-to-wall ratio of 25.2, a glazing U value of 5.77 W/m 2 K, a solar heat gain coefficient of 0.83, an infiltration ratio of 0.5 m 3 /h/m and shading through external roller shutters [40]. The improvement in these openings through solar radiation control was the course project of three multidisciplinary elective courses [33], as previously mentioned. The result are the following six alternatives: A1) Color palette; A2) Frameable; A3) Light frame; A4) Playground; A5) Roof to facade; A6) Wood is good. Table 5 summarizes these alternatives main features. 4. Results The total sustainable index of each alternative and the fulfilment of each requirement and the criteria are depicted in Table 6. These results confirm that the six alternatives are initial designs with room for improvement. They highlight strengths that need to be reinforced and weaknesses that need to be resolved. Most alternatives respond better to economic issues, except for A1 that responds better to social issues. The aspects with the least fulfilment are social in A2, A3 and A6; environmental in A4 and A5; and economic in A1. Four alternatives have a sustainability that is equal or slightly higher than 0.5. In most alternatives, the best performance criteria are cost and fabrication, and assembly environmental impact. In contrast, the worst performance is the environmental impact during the use phase, followed by the user added value, in terms of social issues. Table 7 focuses on some specific indicators and presents I1 and I3 values for each alternative. Appendix I depicts the graphical results. The total cost for the six alternatives ranges between 171.12 € /m 2 (A2) and 306.41 € /m 2 (A1) with four solutions (A2, A3, A5 and A6) that have a very similar total cost range per square meter. A1 and A4 have significantly higher costs. Material costs range between 39.76 € /m 2 (A2) and 100.31 € /m 2 (A1) and represent around 25–30 % of the total costs of each alternative. Due to the varying extension of each alternative in terms of facade surface, overall costs range from € 45,614.38 (A3) to € 110,089.98 (A4). Four solutions have similar ranges (A2, A3, A5, A6), while two alternatives (A1 and A4) have significantly higher ranges. Table 8 focuses on the environmental impact of the six proposals and presents I4, I5, I6, I8, I9 and I10 values for each alternative. Appendix J shows the graphical results of the simplified LCA. The amount of energy required to fabricate and assemble each layer, from the extraction phase to the installation phase, ranges in each solution between 81.12 kWh/m 2 (A3) and 201.09 kWh/m 2 (A4). The embodied carbon of the alternatives ranges from 18.33 Table 5 Six waste-based solar facade concepts developed in the project. Code A1 A2 A3 A4 A5 A6 Name Color palette Frameable Light frame Playground Roof to facade Wood is good General aspect Recycled and reused components palettes, timber profiles, window frames timber profiles, PVC pipes timber for slats bricks, wood formwork roof tile, tile protector wood profiles, PVC pipes Other components steel bars, glue, flashing, paint, cork insulation, membrane, plants anchors, pulleys, tensors, steel cable, glue steel profiles, anchors, metal bar, glue, paint steel profiles, cables, tensor anchor, cork insulation, RC foundation, slab steel profiles, tensors, steel cables, clamps, anchors metal bars, pulleys, metal rings, soil, gravel, plants, rope, anchors Intervention surface per module (m 2 ) 18.6 (facades of classrooms) 18.6 (facades of classrooms) 9.4 (windows of classrooms) 28.6 (whole facade) 18.6 (facades of classrooms) 9.4 (windows of classrooms) Weight (kg/m 2 ) 113.7 25.47 30.24 231.19 34.81 70.35 Circularity (reused + re-cycled) (%) 48.03 54.02 60.80 57.70 77.48 20.65 Legend: PVC: polyvinyl chloride; RC: reinforced concrete. T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 8 kgCO 2 e/m 2 (A3) to 59.16 kgCO 2 e/m 2 (A4). The amount of recycled materials ranges from 0.02% (A1) to 29.00% (A3), whereas the amount of reused materials ranges between 14.95% (A6) and 70.98% (A5). All alternatives have negative energy saving values (I6) compared to a hypothetical nude scenario with no shading device, which would allow maximum use of passive solar heating and lighting through windows. The worst performing case is A4. This solution would increase by 10% the entire building energy demand of the hypothetical nude scenario, which would have a value of 486,576 kWh/a. A2 is the best performing proposal because it would only increase by 2.9% the previously mentioned hypothetical nude scenario. The six initial designs have null energy conversion efficiency (I7) because they are passive but not active solutions. Regarding blocked carbon (I8), the Design Builder simulations show that the integration of plants in the Color palette and Wood is good alternatives contribute to absorbing 0.35 kgCO 2 e/m 2 /a and 0.22 kgCO 2 e/ Table 6 The sustainable index and requirements and criteria fulfilment for the alternatives. C1, R1 C2 (R2) C3 (R2) C4 (R2) R2 C5 (R3) C6 (R3) C7 (R3) R3 SI Alternative Economic Fabrication & assembly Use End of life Environmental Design, production & assembly User comfort User added value Social Total SI A1 Color palette 0.35 0.86 0.28 0.36 0.47 0.70 0.51 0.34 0.52 0.45 A2 Frameable 0.86 0.85 0.03 0.49 0.37 0.42 0.32 0.17 0.31 0.50 A3 Light frame 0.93 0.90 0.00 0.56 0.39 0.17 0.33 0.26 0.27 0.51 A4 Playground 0.66 0.47 0.00 0.52 0.25 0.30 0.28 0.44 0.33 0.39 A5 Roof to facade 0.86 0.80 0.02 0.56 0.37 0.46 0.30 0.61 0.43 0.53 A6 Wood is good 0.77 0.76 0.28 0.32 0.43 0.64 0.33 0.21 0.39 0.52 Table 7 Cost values for the alternatives. Materials & production Cost (I1) Disassembly cost (I3) Materials cost Alternatives All facade ( € ) € /m 2 All facade ( € ) € /m 2 All facade ( € ) € /m 2 A1 Color palette 85,794.26 306.41 57,708.00 206.10 28,086.26 100.31 A2 Frameable 47,914.92 171.12 36,782.82 131.37 11,132.11 39.76 A3 Light frame 45,614.38 162.91 32,009.36 114.32 13,605.02 48.59 A4 Playground 110,089.98 257.22 84,232.05 196.80 25,857.93 60.42 A5 Roof to facade 48,449.33 173.03 35,701.51 127.51 12,747.83 45.53 A6 Wood is good 49,910.60 178.25 38,703.45 138.23 11,207.15 40.03 Section 2, Table 3 and Appendix B explain the calculation of these indicators. Table 8 Environmental values for the alternatives. Embodied energy (I4) Embodied carbon (I5) Energy saving (I6) Blocked carbon (I8) Recycled (I9) Reused (I10) Alternatives kWh/m 2 kgCO 2 e/m 2 kWh/m 2 /a kgCO 2 e/m 2 /a % % A1 Color palette 97.39 18.78 −67.4 1.9*10 −2 0.02% 48.01% A2 Frameable 94.24 25.73 −42.2 −2.66*10 −4 5.00% 54.02% A3 Light frame 81.12 18.33 −75 −2.56*10 −4 29.00% 31.80% A4 Playground 201.09 59.16 −143.7 −2.62*10 −4 6.70% 57.70% A5 Roof to facade 106.31 30.44 −49.3 −2.61*10 −4 6.50% 70.98% A6 Wood is good 133.45 22.54 −90.4 2.41*10 −2 5.70% 14.95% Section 2, Table 3 and appendix B explain the calculation of these indicators. Table 9 Social values for the alternatives. I11 I12 I13 I14 I15 I16 I17 I18 A1 Color palette 0.78 0.67 0.67 0.37 0.89 0.24 0.19 0.64 A2 Frameable 0.78 0.43 0.14 0.24 0.67 0.00 0.00 0.51 A3 Light frame 0.00 0.32 0.19 0.37 0.56 0.00 0.13 0.51 A4 Playground 0.78 0.13 0.03 0.13 0.56 0.13 0.67 0.00 A5 Roof to facade 0.78 0.67 0.04 0.19 0.67 0.00 0.67 0.51 A6 Wood is good 0.90 1.00 0.16 0.24 0.67 0.02 0.02 0.58 Legend: I11 is Design innovation, I12 is Fabrication & ease of assembly, I13 is Flexibility & multifunctionality, I14 is Ventilation performance, I15 Light & visual performance, I16 is Acoustic performance, I17 is User safety added value, and I18 is User interaction & feedback. T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 9 m 2 /a respectively. In contrast, the application of the other four solutions releases slightly more carbon than the hypothetical nude scenario. Table 9 focuses on the social impact of the six proposals and presents I11– I18 values for each alternative. Innovation (I11) is similar in most of the alternatives that have some elements in common with some existing facades. A6 is the most innovative solution that is only similar to some research experiences that are not really built. A3 is similar to available commercial products. Fabrication & ease of assembly (I12) differs among solutions: easy to produce by do it yourself (DIY) and to set up by non-specialists like A6; easy to DIY and to set up by specialists such as A1 and A6; easy to produce in a fab lab (digital fabrication laboratory) and to assemble by specialists like A2; easy to produce in the industry and to assemble by specialists like A3; and difficult to produce and easy to assemble by specialists like A4. Flexibility & multifunctionality (I13) also vary depending on whether the solutions can be hidden (A2), darken the classroom (A1, A3), reduce pollutants (A1, A5, A6), harvest rainwater (A1) or improve the existing facade thermal insulation and thermal storage (A1 and A4). Ventilation performance (I14) discriminates between the capacity of solutions to enhance the air movement. The alternative A1 has the best light and visual performance (I15), while the other alternatives have shortcomings as follows: A2 regarding glare comfort; A3-A6 allowing exterior views; and A2, A3 and A6 providing an aesthetic solution that is well contextualized with the building, in harmony with its originality, proportionality and quality of details. Acoustic performance (I16) is bad in most solutions, except for A1 that enables sealing of the facade layer in the openings and has a soil layer that can insulate from aerial exterior sounds and is less prone to vibrate. A4 and A6 have mass in some facade areas, although A6 is prone to vibrate like the other alternatives. User safety added value (I17) differs between alternatives like A4 and A5, with good fire performance, and alternatives such as A2 and A6 composed of plastics that do not meet current standards. A1 and A6 have the best user interaction and feedback (I18) because the school community can interact with the shading device to modify light levels and visibility according to the learning activities, while feedback is obtained from the growth of the facades’ greenery. In contrast, solutions A2, A3 and A5 only allow some interaction with movements of the shading device. 5. Discussion The methodology followed in this research paper had the flexibility required for the project. The initial design was an interesting, successful, productive step with room for improvement in terms of grouping and coordination, as concluded in the research paper about this teaching experience [33]. Students valued as most positive the personal and collective experiences with the scale 1:1 prototype construction, and the specialization in specific topics regarding the behavior and performance of facade solutions from a technological point of view. The second step involved development of the sustainable assessment tool, to meet the initial objectives presented in the introduction. This tool has the required flexibility, although it has some limitations due to the methodology that was followed, as presented in Section 2. Its applicability is limited to its boundaries. Its subjectivity was limited to a minimum by restricting the possible bias, as explained in Section 2 and appendixes F to H. The social indicators were assessed by assigning points without relying on more objective methodologies such as the social life cycle analysis (SLCA) [67] It was not possible to apply SLCA to the case study due to its lack of maturity and a proper database [68]. The tool constitutes a holistic way of representing the economic, environmental and social sustainability of solutions. It also allows the analysis of individual requirements, specific criteria and their corresponding indicators. As explained in depth in Section 2, this sustainability assessment tool was developed following MIVES and Delphi, through the collaboration of experts and based on earlier research outcomes in the field [14,19,20,37] to obtain a robust tool that minimizes bias. The proposed assessment tool can be used to evaluate and compare waste-based solutions. Solutions can also be compared to similar solutions with non-reused materials to gain a clearer understanding of which indicators could be improved, and which might perform worse. Moreover, this tool follows the boundaries and the decision-makers’ point of view, defined in Sections 1 and 2. Therefore, if this tool had to be used in different contexts, the boundaries and decision-makers’ preferences should be revised to adapt the tool components - indicators, weights and value functions - when necessary. The following subsection further studies the robustness of this new sustainability assessment tool. This project used the most adequate available databases, as presented and justified in Section 2. These databases already incorporate some recycled percentages of material, although they are mainly aimed at non-waste-based materials at present [41]. For Table 10 Sustainable indexes of the weighting scenarios. Sustainability index (SI) of the weighting scenarios Alternatives WS1 Delphi WS2 Uniform Uniform to Delphi WS3 Economic Economic to Delphi WS4 Environment Environment to Delphi WS5 Social Social to Delphi A1 Color palette 0.45 0.45 −1% 0.43 −7% 0.46 0% 0.47 3% A2 Frameable 0.50 0.52 4% 0.60 18% 0.48 −3% 0.46 −7% A3 Light frame 0.51 0.53 4% 0.63 19% 0.49 −3% 0.46 −10% A4 Playground 0.39 0.41 5% 0.48 17% 0.37 −6% 0.39 −1% A5 Roof to facade 0.53 0.55 4% 0.63 16% 0.51 −5% 0.52 −2% A6 Wood is good 0.52 0.53 3% 0.59 13% 0.51 −2% 0.49 −4% T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 16 4 In the second round, the median of the weights was shared with the experts. 5 Experts who had participated in previous similar projects were excluded. G. Qualified experts and their expertise Table 15 Summary of the qualifications of the 15 members of the panel of experts. Number Expertise area Country Organization Score 1 Sustainability Spain University 32 2 Light, solar control Spain University 51 3 Education Spain School 20.5 4 Energy Spain Company 16.5 5 Circular economy Italy University 79.5 6 Automation, intelligence Spain Research center 36 7 Renewable energy systems England University 64.5 8 Facades Spain University 8.5 9 Environmental, LCA El Salvador University 17.5 10 School management Spain Educational administration 163 11 City management Spain City council 9 12 Construction Spain Architectural office 18 13 HVAC Serbia Company 21.5 14 Sustainability Spain Research center 32 15 Construction and architecture Spain Educational department 19.5 H: The results of the two Delphi surveys carried out in this research project T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 17 Table 16 Results from the first round of the survey. Weights assigned by experts in first round Weights assigned by panelist (%) Mean Median Median absolute deviation (%) Consensus Requirements, criteria and indicators R1.1 R1.2 R1.3 R1.4 R1.5 R1.6 R1.7 R1.8 R1.9 R1.10 R1.11 R1.12 R1.13 R1.14 R1.15 R1. Economic 50 20 30 20 33.33 25 25 50 20 30 10 50 25 15 40 29.6 25 10 Yes R2. Environmental 30 40 35 50 33.33 45 40 25 50 30 50 25 45 60 25 38.9 40 9 Yes R3. Social 20 40 35 30 33.33 30 35 25 30 40 40 25 30 25 35 31.6 30 5 Yes C1. Cost 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100.0 100 0 Yes C2. Fabrication & assembly 30 30 50 30 40 15 10 30 40 45 15 15 30 25 35 29.3 30 9 Yes C3. Use 50 50 25 60 30 70 60 50 30 45 70 70 40 50 45 49.7 50 11 No C4. End of life 20 20 25 10 30 15 30 20 30 10 15 15 30 25 20 21.0 20 6 Yes C5. Design & production & assembly added value 25 40 25 45 20 30 30 30 30 40 20 20 35 20 25 29.0 30 6 Yes C6. User comfort 50 40 35 40 50 50 50 30 35 50 40 70 30 40 60 44.7 40 9 Yes C7. User added value 25 20 40 15 30 20 20 40 35 10 40 10 35 40 15 26.3 25 10 Yes I1. Materials & production cost 40 30 35 35 50 60 40 40 50 40 15 70 20 50 20 39.7 40 11 No I2. Annual maintenance & operation cost 40 30 40 50 30 25 40 40 30 50 70 20 50 30 70 41.0 40 11 No I3. Dismantling cost 20 40 25 15 20 15 20 20 20 10 15 10 30 20 10 19.3 20 5 Yes I4. Energy consumption 50 60 50 40 50 30 50 50 50 50 30 50 50 50 65 48.3 50 5 Yes I5. Embodied carbon 50 40 50 60 50 70 50 50 50 50 70 50 50 50 35 51.7 50 5 Yes I6. Annual energy saving 50 30 34 45 50 60 40 50 40 40 30 70 35 50 40 44.3 40 8 Yes I7. Energy conversion efficiency 25 40 33 35 30 20 20 30 20 20 20 20 35 25 40 27.5 25 7 Yes I8. Annual blocked emissions 25 30 33 20 20 20 40 20 40 40 50 10 30 25 20 28.2 25 9 Yes I9. Recyclability 70 50 40 30 70 30 50 60 25 50 60 50 60 40 50 49.0 50 10 Yes I10. Reusability 30 50 60 70 30 70 50 40 75 50 40 50 40 60 50 51.0 50 10 Yes I11. Design innovation 34 50 20 20 20 50 30 20 25 30 20 50 35 35 20 30.6 30 9 Yes I12. Fabrication & ease of assembly 33 25 30 40 40 10 30 40 25 30 40 10 25 25 45 29.9 30 8 Yes I13. Flexibility & multifunctionality 33 25 50 40 40 40 40 40 50 40 40 40 40 40 35 39.5 40 3 Yes I14. Ventilation performance 34 30 35 25 40 33 30 30 35 40 50 40 35 50 45 36.8 35 6 Yes I15. Light & visual performance 33 40 35 40 30 34 40 30 35 40 40 40 40 25 20 34.8 35 5 Yes I16. Acoustic performance 33 40 30 35 30 33 30 40 30 20 10 20 25 25 35 29.1 30 6 Yes I17. User safety added value 70 50 60 70 60 90 40 80 75 90 60 80 60 40 65 66.0 65 12 No I19. User interaction & feedback 30 50 40 30 40 10 60 20 25 10 40 20 40 60 35 34.0 35 12 No T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 18 Table 17 Results from the second round of the survey. Weights assigned by experts in first round Weights assigned by panelist (%) Mean Median Median absolute deviation (%) Consensus Requirements, criteria and indicators R1.1 R1.2 R1.3 R1.4 R1.5 R1.6 R1.7 R1.8 R1.9 R1.10 R1.11 R1.12 R1.13 R1.14 R1.15 R1. Economic 50 20 30 20 33.33 25 25 50 20 30 10 50 25 15 40 29.6 25 10 Yes R2. Environmental 30 40 35 50 33.33 45 40 25 50 30 50 25 45 60 25 38.9 40 9 Yes R3. Social 20 40 35 30 33.33 30 35 25 30 40 40 25 30 25 35 31.6 30 5 Yes C1. Cost 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100.0 100 0 Yes C2. Fabrication & assembly 30 30 35 30 35 25 20 30 30 45 20 25 30 25 35 29.7 30 4 Yes C3. Use 50 50 40 55 40 60 55 50 40 32.5 60 60 50 50 45 49.2 50 6 Yes C4. End of life 20 20 25 15 25 15 25 20 30 22.5 20 15 20 25 20 21.2 20 3 Yes C5. Design & production & assembly added value 25 40 25 45 20 30 30 30 30 40 20 20 35 20 25 29.0 30 6 Yes C6. User comfort 50 40 35 40 50 50 50 30 35 50 40 70 30 40 60 44.7 40 9 Yes C7. User added value 25 20 40 15 30 20 20 40 35 10 40 10 35 40 15 26.3 25 10 Yes I1. Materials & production cost 40 35 35 35 40 60 40 40 45 40 20 55 30 45 35 39.7 40 6 Yes I2. Annual maintenance & operation cost 40 35 40 45 40 25 40 40 35 45 60 35 40 35 50 40.3 40 5 Yes I3. Dismantling cost 20 30 25 20 20 15 20 20 20 15 20 10 30 20 15 20.0 20 3 Yes I4. Energy consumption 50 30 34 45 50 60 40 50 40 40 30 70 35 50 40 44.3 40 8 Yes I5. Embodied carbon 25 40 33 35 30 20 20 30 20 20 20 20 35 25 40 27.5 25 7 Yes I6. Annual energy saving 25 30 33 20 20 20 40 20 40 40 50 10 30 25 20 28.2 25 9 Yes I7. Energy conversion efficiency 50 60 50 40 50 30 50 50 50 50 30 50 50 50 65 48.3 50 5 Yes I8. Annual blocked emissions 50 40 50 60 50 70 50 50 50 50 70 50 50 50 35 51.7 50 5 Yes I9. Recyclability 70 50 40 30 70 30 50 60 25 50 60 50 60 40 50 49.0 50 10 Yes I10. Reusability 30 50 60 70 30 70 50 40 75 50 40 50 40 60 50 51.0 50 10 Yes I11. Design innovation 34 50 20 20 20 50 30 20 25 30 20 50 35 35 20 30.6 30 9 Yes I12. Fabrication & ease of assembly 33 25 30 40 40 10 30 40 25 30 40 10 25 25 45 29.9 30 8 Yes I13. Flexibility & multifunctionality 33 25 50 40 40 40 40 40 50 40 40 40 40 40 35 39.5 40 3 Yes I14. Ventilation performance 34 30 35 25 40 33 30 30 35 40 50 40 35 50 45 36.8 35 6 Yes I15. Light & visual performance 33 40 35 40 30 34 40 30 35 40 40 40 40 25 20 34.8 35 5 Yes I16. Acoustic performance 33 40 30 35 30 33 30 40 30 20 10 20 25 25 35 29.1 30 6 Yes I17. User safety added value 70 60 60 70 60 90 55 75 65 70 60 70 60 60 65 66.0 65 6 Yes I19. User interaction & feedback 30 40 40 30 40 10 45 25 35 30 40 30 40 40 35 34.0 35 6 Yes T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 19 I: Graphical results of the simplified LCC Fig. 3. Materials and production cost of the six initial designs. Fig. 4. Disassembly cost of the six initial designs. Fig. 5. Materials cost of the six initial designs. J: Graphical results of the simplified LCA T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 20 Fig. 6. Energy consumption of the six initial designs. Fig. 7. GHG emissions of the six initial designs. Fig. 8. Percentage of reused material in weight of the six initial designs. References [1] O. Pons, G. Wadel, Environmental impacts of prefabricated school buildings in Catalonia, Habitat Int. 35 (2011) 553–563, https://doi.org/10.1016/j. habitatint.2011.03.005. [2] K. Ahmed Ali, M.I. Ahmad, Y. Yusup, Issues, impacts, and mitigations of carbon dioxide emissions in the building sector, Sustainability 12 (2020), https://doi. org/10.3390/su12187427. [3] EU, Regulation (EU) 2021/1119 of the European Parliament and of the Council of 30 June 2021 Establishing the Framework for Achieving Climate Neutrality and Amending Regulations, 2021. [4] EU, Regulation (EU) 2018/1999 of the European Parliament and of the Council of 11 December 2018 on the Governance of the Energy Union and Climate Action, Amending Regulations (EC) No 663/2009 and (EC) No 715/2009 of the European Parliament and of the Council, 2018. [5] M.R. Esa, A. Halog, L. Rigamonti, Developing strategies for managing construction and demolition wastes in Malaysia based on the concept of circular economy, J. Mater. Cycles Waste Manag. 19 (2017) 1144–1154, https://doi.org/10.1007/s10163-016-0516-x. [6] C. Bertozzi, How is the construction sector perceiving and integrating the circular economy paradigm? Insights from the Brussels experience, City, Culture and Society 29 (2022) 100446, https://doi.org/10.1016/j.ccs.2022.100446. T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 21 [7] IEA, Energy Efficiency - the Decade for Action, 2023. Versailles. [8] COM, A Renovation Wave for Europe – greening our buildings, Creating Jobs, improving lives, Brussels, 2020. [9] EP, CEU, Directive 2008/98/EC on Waste (Waste Framework Directive), 2008. [10] JE, BOE-A-2022-9838, 2022. [11] G. Ledesma, O. Pons-Valladares, J. Nikolic, Real-reference buildings for urban energy modelling: a multistage validation and diversification approach, Build. Environ. 203 (2021) 108058, https://doi.org/10.1016/j.buildenv.2021.108058. [12] G. Ledesma, J. Nikolic, O. Pons-Valladares, Co-simulation for thermodynamic coupling of crops in buildings. Case study of free-running schools in Quito, Ecuador, Build. Environ. 207 (2022) 108407, https://doi.org/10.1016/j.buildenv.2021.108407. [13] M. Brkovic, O. Pons, R. Parnell, Where sustainable school meets the ‘third teacher’: primary school case study from Barcelona, Spain, Int. J. Architect. Res.: ArchNet-IJAR 9 (2015) 77–97. http://hdl.handle.net/2117/77060 (accessed February 7, 2024). [14] G. Gilani, O. Pons, A. de la Fuente, Sustainability-oriented approach to assist decision makers in building facade management, J. Construct. Eng. Manag. 148 (2022) 4021182, https://doi.org/10.1061/(ASCE)CO.1943-7862.0002194. [15] E.K. Zavadskas, A. Kaklauskas, Z. Turskis, J. Tamoˇ saitien˙ e, Selection of the effective dwelling house walls by applying attributes values determined at intervals, J. Civ. Eng. Manag. 2 (2008) 85–93, https://doi.org/10.3846/1392-3730.2008.14.3. [16] S. Sarihi, F. Mehdizadeh Saradj, M. Faizi, A critical review of façade retrofit measures for minimizing heating and cooling demand in existing buildings, Sustain. Cities Soc. 64 (2021) 102525, https://doi.org/10.1016/j.scs.2020.102525. [17] M. Kiil, R. Simson, F. de Luca, M. Thalfeldt, J. Kurnitski, Overheating and daylighting evaluation for free-running classroom designs, IOP Conf. Ser. Earth Environ. Sci. 352 (2019) 12059, https://doi.org/10.1088/1755-1315/352/1/012059. [18] S. Habibi, O. Pons, D.M. Pe˜ na, Sustainability performance by ten representative intelligent Façade technologies: a systematic review, Sustain. Energy Technol. Assessments 52 (2022) 102001, https://doi.org/10.1016/j.seta.2022.102001. [19] G. Gilani, S.M.A. Hosseini, O. Pons-Valladares, A. de la Fuente, An enhanced multi-criteria decision-making approach oriented to sustainability analysis of building facades: a case study of Barcelona, J. Build. Eng. 54 (2022) 104630, https://doi.org/10.1016/j.jobe.2022.104630. [20] S. Habibi, O. Pons Valladares, D. Pe˜ na, New sustainability assessment model for Intelligent Façade Layers when applied to refurbish school buildings skins, Sustain. Energy Technol. Assessments 42 (2020) 100839, https://doi.org/10.1016/j.seta.2020.100839. [21] N. Utaberta, A. Jalali, S. Johar, M. Surat, A.I. Che-Ani, Building facade study in lahijan city, Iran: the impact of facade’s visual elements on historical image, Int. J. Humanit. Soc. Sci. 6 (2012) 1839–1844, https://doi.org/10.5281/zenodo.1331711. [22] P. Tsikra, E. Andreou, Investigation of the energy saving potential in existing school buildings in Greece. The role of shading and daylight strategies in visual comfort and energy saving, Procedia Environ. Sci. 38 (2017) 204–211, https://doi.org/10.1016/j.proenv.2017.03.107. [23] J. B¨ oke, P.-R. Denz, N. Suwannapruk, P. Vongsingha, Active, passive and cyber-physical adaptive façade strategies: a comparative analysis through case studies, J. Facade Des. Eng. 10 (2022) 1–18, https://doi.org/10.47982/jfde.2022.powerskin.01. [24] K. Dewidar, A.H. Mahmoud, N. Magdy, S. Ahmed, The role of intelligent façades in energy conservation, in: International Conference on Sustainability and the Future: Future Intermediate Sustainable Cities (FISC 2010), 2010. [25] O. Pons, D. Pe˜ na, S. Habibi, New Solar Control Tensed Devices for Workshops about Sustainable School Architecture, 2018. [26] T. Ramesh, R. Prakash, K.K. Shukla, Life cycle energy analysis of buildings: an overview, Energy Build. 42 (2010) 1592–1600, https://doi.org/10.1016/j. enbuild.2010.05.007. [27] M.C. Pinto, G. Crespi, F. Dell’Anna, C. Becchio, Combining energy dynamic simulation and multi-criteria analysis for supporting investment decisions on smart shading devices in office buildings, Appl. Energy 332 (2023) 120470, https://doi.org/10.1016/j.apenergy.2022.120470. [28] I. Yitmen, A. Al-Musaed, F. Yücelgazi, ANP model for evaluating the performance of adaptive façade systems in complex commercial buildings, Eng. Construct. Architect. Manag. 29 (2022) 431–455, https://doi.org/10.1108/ECAM-07-2020-0559. [29] C. Sivaji, P.K. Chidambaram, M. Ramachandran, A. Murugan, Performance analysis of facade materials using VIKOR method, REST J. Adv. Mech. Eng. 2 (2022) 41–49, https://doi.org/10.46632/jame/1/2/6. [30] J. Zhao, Y. Du, Multi-objective optimization design for windows and shading configuration considering energy consumption and thermal comfort: a case study for office building in different climatic regions of China, Sol. Energy 206 (2020) 997–1017, https://doi.org/10.1016/j.solener.2020.05.090. [31] J. Yoon, S. Bae, Performance evaluation and design of thermo-responsive SMP shading prototypes, Sustainability 12 (2020), https://doi.org/10.3390/ su12114391. [32] O. Pons, S. Habibi, D. Pe˜ na, Sustainability assessment of household waste based solar control devices for workshops in primary schools, Sustainability 10 (2018) 4071, https://doi.org/10.3390/su10114071. [33] O. Pons, T. Masseck, M. Bosch, Transversal learning process towards the research of architecture and its sustainability, in: ICERI Proceedings, Seville, 2023, pp. 558–564, https://doi.org/10.21125/iceri.2023.0203. [34] Wiser, Wiser Courses. https://wiser.upc.edu/iniciiniciohome/home/courses, 2023 (accessed February 22, 2024). [35] D. Boix-Cots, F. Pardo-Bosch, A. Blanco, A. Aguado, P. Pujadas, A systematic review on MIVES: a sustainability-oriented multi-criteria decision-making method, Build. Environ. 223 (2022) 109515, https://doi.org/10.1016/j.buildenv.2022.109515. [36] M. del M. Casanovas-Rubio, J. Armengou, Decision-making tool for the optimal selection of a domestic water-heating system considering economic, environmental and social criteria: application to Barcelona (Spain), Renew. Sustain. Energy Rev. 91 (2018) 741–753, https://doi.org/10.1016/j. rser.2018.04.040. [37] O. Pons, D. Pe˜ na, S. Habibi, New solar control tensed devices for workshops about sustainable school architecture. https://www.researchgate.net/project/Newsolar-control-tensed-devices-for-workshops-about-sustainable-school-architecture, 2018 (accessed May 12, 2019). [38] O. Pons, A. de la Fuente, A. Aguado, The use of MIVES as a sustainability assessment MCDM method for architecture and civil engineering applications, Sustainability (2016), https://doi.org/10.3390/su8050460. [39] O. Pons-Valladares, J. Nikolic, Sustainable design, construction, refurbishment and restoration of architecture: a review, Sustainability 12 (2020), https://doi. org/10.3390/su12229741. [40] M.G. Ledesma Hidalgo, Passive Mosaic Energy Optimization: toward Free-Running School Buildings, Universitat Polit` ecnica de Catalunya, 2022. [41] ITEC, ITEC metaBase Banc BEDEC 2021. https://itec.cat/banc-preus-bedec/, 2023 (accessed October 6, 2023). [42] Cypedoc Cype, Manual de uso y mantenimiento del edificio (n.d.), https://info.cype.com/es/producto/cypedoc-manual-de-uso-y-mantenimiento-del-edificio/ (accessed October 25, 2023). [43] A. de la Fuente, J. Armengou, O. Pons, A. Aguado, Multi-criteria decision-making model for assessing the sustainability index of wind-turbine support systems: application to a new precast concrete alternative, J. Civ. Eng. Manag. 23 (2017), https://doi.org/10.3846/13923730.2015.1023347. [44] O. Pons, S. Habibi, D. Pe˜ na, Sustainability assessment of household waste based solar control devices for workshops in primary schools, Sustainability 10 (2018) 4071, https://doi.org/10.3390/su10114071. [45] J. Lee, M. Alshayeb, J.D. Chang, A study of shading device configuration on the natural ventilation efficiency and energy performance of a double skin façade, Procedia Eng. 118 (2015) 310–317, https://doi.org/10.1016/j.proeng.2015.08.432. [46] A. Faraji, F. Rezaei, P. Rahnamayiezekavat, M. Rashidi, H. Soleimani, Subjective and simulation-based analysis of discomfort glare metrics in office buildings with light shelf systems, Sustainability 15 (2023), https://doi.org/10.3390/su151511885. [47] O. Pons-Valladares, M. del M. Casanovas-Rubio, J. Armengou, A. de la Fuente, Approach for sustainability assessment for footbridge construction technologies: application to the first world D-shape 3D-Printed fiber-reinforced mortar footbridge in Madrid, J. Clean. Prod. 394 (2023) 136369, https://doi.org/10.1016/j. jclepro.2023.136369. [48] O. Pons, T. Abt, Evaluation of household waste materials for façade components in primary educational workshops. Mechanical and fire properties, J. Build. Eng. 29 (2020) 101202, https://doi.org/10.1016/j.jobe.2020.101202. [49] M. Oele, R. Dolfing, SimaPro 9.1.1 | Full Update Instructions, 2020. T. Masseck et al. Journal of Building Engineering 87 (2024) 109024 22 [50] Ecoinvent, ecoinvent v3.6. https://ecoinvent.org/the-ecoinvent-database/data-releases/ecoinvent-3-6/, 2019 (accessed October 13, 2023). [51] ISO, ISO 14040:2006 Environmental Management — Life Cycle Assessment — Principles and Framework, 2006. ISO 14040:2006/A1 September 2021, (n.d. [52] ISO, ISO 14044 Environmental Management – Life Cycle Assessment – Requirements and Guidelines, 2006. ISO 14044:2006/A1 November 2018; ISO 14044: 2006/A2 July 2021., Switzerland, n.d. [53] CEN, UNE-EN 15804:2012+A2:2019 Sustainability of Construction Works - Environmental Product Declarations - Core Rules for the Product Category of Construction Products. UNE-EN 15804:2012+A2:2020/AC, 2019. October 2021, Brussels. [54] Y. Decorte, M. Steeman, N. Van Den Bossche, Effect of a one-dimensional approach in LCA on the environmental life cycle impact of buildings: multi-family case study in Flanders, Build. Environ. 206 (2021) 108381, https://doi.org/10.1016/j.buildenv.2021.108381. [55] I. Josa, O. Pons, A. de la Fuente, A. Aguado, Multi-criteria decision-making model to assess the sustainability of girders and trusses: case study for roofs of sports halls, J. Clean. Prod. 249 (2020) 119312, https://doi.org/10.1016/j.jclepro.2019.119312. [56] G. Gilani, MCDM Approach for Assessing the Sustainability of Buildings’ Facades, Universitat Polit` ecnica de Catalunya, 2020. [57] S.M. Zolfaghari, O. Pons, J. Nikolic, Sustainability assessment model for mass housing’s interior rehabilitation and its validation to Ekbatan, Iran, J. Build. Eng. 65 (2023) 105685, https://doi.org/10.1016/j.jobe.2022.105685. [58] O. Pons, A. Aguado, Integrated value model for sustainable assessment applied to technologies used to build schools in Catalonia, Spain, Build. Environ. 53 (2012) 49–58, https://doi.org/10.1016/j.buildenv.2012.01.007. [59] C. Okoli, S.D. Pawlowski, The Delphi method as a research tool: an example, design considerations and applications, Inf. Manag. 42 (2004) 15–29, https://doi. org/10.1016/j.im.2003.11.002. [60] P. Bromley, Using nominal group technique (NGT) to reach consensus on graduate attributes for nurses undertaking postgraduate certification in neonatal intensive care in Australia, J. Neonatal Nurs. 20 (2014) 245–252, https://doi.org/10.1016/j.jnn.2014.08.002. [61] B. Alarcon, A. Aguado, R. Manga, A. Josa, A value function for assessing sustainability: application to industrial buildings, Sustainability 3 (2011) 35–50, https://doi.org/10.3390/su3010035. [62] B. Vi˜ nolas, Aplicaciones y avances de la metodología MIVES en valoraciones multicriterio. (Applications and Advances of MIVES Methodology in Multi-Criteria Assessments), UPC, 2011. [63] Cypedoc Cype, Manual de uso y mantenimiento del edificio (n.d.), https://info.cype.com/es/producto/cypedoc-manual-de-uso-y-mantenimiento-del-edificio/ (accessed October 25, 2023). [64] S. Habibi, O. Pons, T. Abt, Evaluation of household waste materials for façade components in primary educational workshops. Degradation behavior and mechanical properties of aged samples, J. Build. Eng. 33 (2021), https://doi.org/10.1016/j.jobe.2020.101573. [65] D.E. Hebel, M.H. Wisniewska, F. Heisel, Building from Waste: Recovered Materials in Architecture and Construction, Birkh¨ auser, 2014, https://doi.org/ 10.1515/9783038213758. [66] Spanish Ministry of transport mobility and urban agenda, Documento Basico HE, 2022. [67] V.G. Larsen, N. Tollin, P.A. Sattrup, M. Birkved, T. Holmboe, What are the challenges in assessing circular economy for the built environment? A literature review on integrating LCA, LCC and S-LCA in life cycle sustainability assessment, LCSA, J. Build. Eng. 50 (2022) 104203, https://doi.org/10.1016/j. jobe.2022.104203. [68] P. Ayassamy, R. Pellerin, Social life-cycle assessment in the construction industry: a review of characteristics, limitations, and challenges of S-LCA through case studies, Sustainability 15 (2023), https://doi.org/10.3390/su151914569. [69] EPD HYDRO, Environmental Product Declaration for Hydro Recycled Low Carbon Aluminium Profiles Produced by Hydro Extrusion Iberia, Stockholm. https:// api.environdec.com/api/v1/EPDLibrary/Files/899f0587-a16a-4ccc-8118-08dbb657dbae/Data, 2023 (accessed November 29, 2023). [70] E.P.D. HATKO, Environmental Product Declaration Recycled Rubber Sound Barrier, Istanbul, 2022. https://epd.dijitalpanel.site/Upload/epdturkey.com/ Products/Images/64db2ce545127-EN%20S-P-04129_Construction_Hatko_Rubber%20Sound%20Barrier_EN_EPDTurkey.pdf (accessed November 29, 2023). [71] Institut Bauen und Umwelt, Umwelt-Produktdeklaration Gipsfaserplatte, Berlin, 2022. https://www.knauf.es/sites/default/files/2023-11/epd_gipsfaserplatten_ de2%20%281%29.pdf (accessed November 29, 2023). [72] EPD AENOR FdA IECA, Declaraci´ on Ambiental de Producto, ´ Aridos Reciclados, 2020. Madrid, https://www.aenor.com/Producto_DAP_pdf/DAP%20A%CC% 81ridos%20Reciclados%20GlobalEPD%20EN15804-026%20rev1.pdf (accessed November 30, 2023). [73] M. Buyle, W. Galle, W. Debacker, A. Audenaert, Sustainability assessment of circular building alternatives: consequential LCA and LCC for internal wall assemblies as a case study in a Belgian context, J. Clean. Prod. 218 (2019) 141–156, https://doi.org/10.1016/j.jclepro.2019.01.306. [74] B. Sanchez, C. Rausch, C. Haas, R. Saari, A selective disassembly multi-objective optimization approach for adaptive reuse of building components, Resour. Conserv. Recycl. 154 (2020) 104605, https://doi.org/10.1016/j.resconrec.2019.104605. [75] F. Cappelletti, M. Rossi, M. Germani, How de-manufacturing supports circular economy linking design and EoL - a literature review, J. Manuf. Syst. 63 (2022) 118–133, https://doi.org/10.1016/j.jmsy.2022.03.007. [76] M.R. Munaro, S.F. Tavares, L. Bragança, Towards circular and more sustainable buildings: a systematic literature review on the circular economy in the built environment, J. Clean. Prod. 260 (2020) 121134, https://doi.org/10.1016/j.jclepro.2020.121134. [77] C. Mascle, Product design for rebirth: application to aircraft life cycle modeling, supply chain forum, Int. J. 14 (2013) 70–83, https://doi.org/10.1080/ 16258312.2013.11517316. [78] H. Abuzied, H. Senbel, M. Awad, A. Abbas, A review of advances in design for disassembly with active disassembly applications, Engineering Science and Technology, an International Journal 23 (2020) 618–624, https://doi.org/10.1016/j.jestch.2019.07.003. [79] Md.U. Hossain, S.T. Ng, P. Antwi-Afari, B. Amor, Circular economy and the construction industry: existing trends, challenges and prospective framework for sustainable construction, Renew. Sustain. Energy Rev. 130 (2020) 109948, https://doi.org/10.1016/j.rser.2020.109948. [80] DGNB GBCe RFBB ¨ OGNI CPEA SGNI DGBC, CIRCULAR ECONOMY TAXONOMY STUDY Assessing the Market-Readiness of the Proposed Circular Economy EU- Taxonomy Criteria for Buildings, 2023. T. Masseck et al.